I critically evaluate the influential new wave account of theory reduction in science developed by Paul Churchland and Clifford Hooker. First, I cast doubt on claims that the new wave account enjoys a number of theoretical virtues over its competitors, such as the ability to represent how false theories are reduced by true theories. Second, I argue that the genuinely novel claim that a corrected theory must be specified entirely by terms from the basic reducing theory is in fact too (...) restrictive for scientific practice and should be rejected. Basic theories co-evolve with nonbasic theories in a mutually interactive way, and thus the basic theories incorporate the concepts and concerns of nonbasic theories. Third, I show that once its ontological consequences are duly noted, the reductive part the new wave account collapses into the classical theory developed within the logical empiricist tradition. As such, it still falls prey to standard anti-reductionist argument based upon multiple realizability and the cross-classification of special science and physical science terms. (shrink)

No-one can read far into our subject without finding an author linking aesthetic experience and freedom in one sense or another: Kant, notably of course, but also Schopenhauer, Schiller, and many more. In this article I want first [A] to remind you in a sentence or two of those by now classic ways of connecting concepts of freedom and aesthetic experience, and then [B] to outline some thoughts of my own. Section [C] opens up in more detail a less frequented (...) and less well-charted topic: basically, the many- layered nature of much aesthetic experience, and how that can involve freedom in an ‘improvisatory’ contribution by the apprec iator. Each layer can be thought of as containing a ‘given’—the product of earlier syntheses, plus a new component, in its turn, to be synthesized, whether historical, scientific, religious, or other. This probably occurs most of all in the aesthetic appreciation of nature, since art offers some controlling, ‘mastering’ of the appreciator’s response. (shrink)

In light of the phenomenon of multiple realizability, many philosophers wanted to preserve the mind-brain identity theory by resorting to a “narrow reductive strategy” whereby one (a) finds mental properties which are (b) sufficiently narrow to avoid the phenomenon of multiple realization, while being (c) explanatorily adequate to the demands of psychological theorizing. That is, one replaces the conception of a mental property as more general feature of cognitive systems with many less general properties, for example, replacing the conception of (...) pain as a general property across different species with a number of species-specific kinds of pain. Many critics focused on (c), arguing that species-specific properties are not explanatorily adequate because they do not capture what is common in pain across species. In this paper I focused on (b). I argued that if one carries the narrow reductive strategy out in such a way to avoid all multiple realizability that occurs within a species, for example, accommodating individual differences by postulating a more narrow pain-relative-to-an-individual-at-a-time, then the result is for all intents and purposes a claim about tokens and not types or properties at all (the position is now about individuals having properties at times, a structured token event). I also added an important point about explanation, viz., that properties-relative-to-individuals-at-times would not serve the explanatory goals of science by failing to generalize to other individuals. (shrink)

I critically evaluate Bickle’s version of scientific theory reduction. I press three main points. First, a small point, Bickle modifies the new wave account of reduction developed by Paul Churchland and Clifford Hooker by treating theories as set-theoretic structures. But that structuralist gloss seems to lose what was distinctive about the Churchland-Hooker account, namely, that a corrected theory must be specified entirely by terms and concepts drawn from the basic reducing theory. Set-theoretic structures are not terms or concepts but the (...) structures that they describe. Second, and more serious, a familiar problem for classical positivist account of reduction resurfaces within this newest wave of thinking, namely, commitment to property identities and inter-theoretic bridge laws (a problem I discussed at more length in "Collapse of the New Wave"). Indeed, this problem is exacerbated by Bickle’s conciliatory treatment of property plasticity, since he is willing to grant that a large number of special science terms denote multiply realized properties, at least if realistically construed. Still, in the end, Bickle sidesteps the reduction of properties by appealing to Hooker’s "function-to-structure token reduction." This is an interesting move with an intriguing concept of reduction. But problems remain. For, third, Bickle and Hooker's function-to-structure token reduction is actually a guised form of eliminative materialism. But that should be unacceptable since the position extends well beyond any modest revisionism for suspect items from a folk theory, say, in folk psychology or folk biology. Instead, it applies to functional terms and concepts employed throughout well-developed and explanatorily successful sciences. (shrink)

D. C. Matthew argues that although integration offers blacks social and economic benefits, it also creates the conditions for phenotypic devaluation that leads to harm against black self-worth and servile behavior. Therefore, he advises against integration because the resulting self-worth harms outweigh the benefits of integration. I argue that Matthew’s cost-benefit calculation against integration lacks the requisite evidence, and amounts to a luxury belief that will result in more harm. Moreover, his interpretation of behavior — which he construes as being (...) indicative of a lack of self-worth — is unfounded. Further, his cost-benefit calculation results in socially reactionary sexual policing and ideological purity tests. (shrink)

Synthetic organisms are at the same time organisms and artifacts. In this paper we aim to determine whether such entities have a good of their own, and so are candidates for being directly morally considerable. We argue that the good of non-sentient organisms is grounded in an etiological account of teleology, on which non-sentient organisms can come to be teleologically organized on the basis of their natural selection etiology. After defending this account of teleology, we argue that there are no (...) grounds for excluding synthetic organisms from having a good also grounded in their teleological organization. However, this comes at a cost; traditional artifacts will also be seen as having a good of their own. We defend this as the best solution to the puzzle about what to say about the good of synthetic organisms. (shrink)

In this commentary, I critique three aspects of Emily Walsh's proposal to reduce the moral and legal weight of advance directives: (1) the ambiguity of its initial thesis, (2) its views about the ethics and legality of clinical practice, and (3) its interpretation and application of Ronald Dworkin’s account of advance directives and L.A. Paul's view on transformative experience. I also consider what Walsh’s proposal would mean for people facing the prospect of dementia. I conclude that our reasons to (...) honor many advance directives survive the move to a transformative experience framework. (shrink)

Two controversies exist regarding the appropriate characterization of hierarchical and adaptive evolution in natural populations. In biology, there is the Wright-Fisher controversy over the relative roles of random genetic drift, natural selection, population structure, and interdemic selection in adaptive evolution begun by Sewall Wright and Ronald Aylmer Fisher. There is also the Units of Selection debate, spanning both the biological and the philosophical literature and including the impassioned group-selection debate. Why do these two discourses exist separately, and interact relatively (...) little? We postulate that the reason for this schism can be found in the differing focus of each controversy, a deep difference itself determined by distinct general styles of scientific research guiding each discourse. That is, the Wright-Fisher debate focuses on adaptive process, and tends to be instructed by the mathematical modeling style, while the focus of the Units of Selection controversy is adaptive product, and is typically guided by the function style. The differences between the two discourses can be usefully tracked by examining their interpretations of two contested strategies for theorizing hierarchical selection: horizontal and vertical averaging. (shrink)

FISIOLOGIA DO PARTO E DA LACTAÇÃO ANIMAL -/- ANIMAL REPRODUCTION: PHISIOLOGY OF PARTURITION AND ANIMAL LACTATION -/- Emanuel Isaque Cordeiro da Silva Departamento de Zootecnia da UFRPE WhatsApp: (82)98143-8399 -/- 1. INTRODUÇÃO O sucesso biológico do processo de reprodução culmina com a sobrevivência das crias. Durante a gestação, o feto desenvolve-se no útero materno protegido das influências externas, e obtendo os nutrientes e o oxigênio através da mãe. O parto é o processo biológico que marca o fim da gestação e (...) o início da vida extrauterina do animal. Para garantir a sobrevivência do recém-nascido o parto deve ser um processo controlado para que se inicie unicamente quando o feto tiver alcançado desenvolvimento suficiente que lhe permita enfrentar a vida extrauterina. Após o nascimento, a secreção de leite pela glândula mamária proporciona ao neonato tanto os nutrientes necessários para seu desenvolvimento como as defesas (imunoglobulinas) que lhe protegerão contra as possíveis infecções durante as primeiras fases de sua vida. Parto e lactação constituem a última etapa de um ciclo reprodutivo completo nas fêmeas dos animais domésticos, estando ambos os processos regulados e sincronizados por complexas mudanças hormonais na mãe. Estas mudanças são, em última análise, provocadas e governadas pelo próprio feto ou recém-nascido, o qual acomoda as respostas maternas às suas necessidades garantindo a sua sobrevivência. 2. O PARTO O parto é definido como o processo fisiológico pelo qual ocorre a expulsão de um ou mais fetos maduros, bem como das membranas fetais existentes no útero materno. Este processo é desencadeado por uma interação complexa entre as hormonas maternas (fatores maternos) e fetais (fatores fetais). Para que se realize a expulsão do feto é necessário que o útero deixe de ser um órgão quiescente, essencial para a manutenção da gestação, para ser um órgão contrátil. Ao mesmo tempo, o cérvix ou colo uterino, que durante a gestação permanece firmemente fechado para impedir a expulsão prematura do feto e evitar a entrada de agentes infecciosos, relaxa e dilata para facilitar a passagem do feto na hora do parto. Esta modificação na atividade do útero e do colo uterino, ocorrem como consequência das mudanças hormonais que o organismo materno experimenta à medida que a data do parto se aproxima. 2.1 Fatores maternos A gestação dos animais domésticos ocorre com elevada concentração de progesterona que, dependendo da espécie animal, é secretada seja pelo corpo lúteo do ovário (vaca, porca e cabra) ou pela placenta (ovelha e égua). A progesterona desempenha um papel fundamental durante a gestação, inibindo as contrações da musculatura lisa do útero (miométrio), permitindo assim a acomodação do feto durante o seu crescimento. Os estrogênios, estimulantes da atividade contrátil do miométrio, mantêm-se a baixas concentrações durante a maior parte da gestação. À medida que se aproxima o momento do parto, os níveis destes hormônios esteroides modificam-se, produzindo-se a diminuição nos níveis circulantes da progesterona ao mesmo tempo que se incrementam os valores sanguíneos dos estrogênios (figura 1). A redução dos níveis de progesterona suprime a sua ação inibitória sobre a atividade contrátil do miométrio, permitindo que se manifestem os efeitos estimulantes dos estrogênios sobre este órgão. A concentração de estrogênios começa a aumentar geralmente no final da gestação, atingindo os seus valores máximos no momento do parto (figura 1). O aumento da concentração de estrogênios favorece a atividade contrátil espontânea do útero ao: a) estimular a síntese de proteínas contráteis; b) aumentar, sob medida, a sensibilidade do miométrio uterino à ação estimulante das prostaglandinas; c) induzir a formação de receptores de oxitocina no útero. -/- Figura 1. Níveis de progesterona e estrógenos durante a gestação e parto das espécies ovina, caprina, suína e bovina. Fonte: HAFEZ, 2013. Os estrogênios estimulam a síntese e secreção de prostaglandina (PGF2a), que constitui o elemento essencial para o início do parto devido aos efeitos que esta substância provoca. Assim, nas fêmeas, cujos níveis de progesterona gestacional dependem da presença do corpo lúteo, a secreção de PGF, origina a regressão deste (luteólise), com a consequente diminuição da progesterona a níveis basais. Além disso, a PGF2a origina contrações de crescente intensidade no útero sensibilizado pela ação dos estrogênios. Esta ação contrátil da PGF2a deve-se a um aumento da concentração de cálcio intracelular das fibras musculares uterinas. A PGF2a também está envolvida no relaxamento do colo do útero, inibindo a formação de colágeno cervical ao mesmo tempo que estimula a síntese de enzimas (colagenase) que degradam a matriz de colágeno formado no início da gestação. A dilatação do colo do útero está também associada à pressão que o feto exerce sobre o mesmo e, no caso da porca, a relaxina pode também estar envolvida. Esta hormona é também de grande importância para a preparação do parto em todas as espécies animais, uma vez que é responsável pelo relaxamento dos ligamentos e músculos que rodeiam o canal pélvico para favorecer a separação da sínfise púbica durante a expulsão do feto. Nos grandes animais (vaca, égua) as mudanças que ocorrem nos tecidos e ligamentos pélvicos são muito evidentes e constituem um sintoma de parto iminente. O início do parto, ou primeira fase do parto, caracteriza-se pelo aumento das contrações uterinas provocadas pela PGF2a coincidindo com a dilatação do colo uterino para permitir a passagem do feto para o canal do parto, momento em que começa a segunda fase do parto. A distensão vaginal que produz-se para a passagem do feto pelo canal do parto origina um estímulo nervoso que viaja através da medula espinal para o hipotálamo, onde se encontram os neurônios responsáveis pela síntese de oxitocina. As terminações nervosas destes neurónios são projetadas para o lobo posterior da hipófise (neurohipófise), onde a oxitocina é secretada para ser, posteriormente , transportada pela circulação sanguínea. Este reflexo neuroendócrino chamado reflexo de Ferguson determina a secreção súbita de oxitocina, provocando o aumento tanto na intensidade como na frequência das contrações uterinas necessárias para a expulsão final do feto. O papel da oxitocina é ativar a conclusão do processo de expulsão, uma vez que esta hormona não está envolvida no início do parto. A alteração mais significativa entre a gestação e o parto é a alteração na atividade contrátil do miométrio uterino. Esta mudança é devido às alterações hormonais que ocorrem na mãe quando a gestação chegou a fim. No entanto, para que estes mecanismos maternos sejam acionados, é necessário que o feto indique de alguma forma à mãe o seu estado de desenvolvimento, de modo que o nascimento realize-se quando o feto estiver preparado para enfrentar a vida extrauterina. 2.2 Fatores fetais A destruição experimental da hipófise e/ou das glândulas adrenais do feto origina o prolongamento da gestação nos animais domésticos. Pelo contrário, a administração exógena de cortisol (corticosteroides adrenais), ou do seu precursor hipofisário (ACTH), à circulação fetal provoca, em poucas horas, o início do parto. Estes fatos evidenciam a importância do eixo hipófise-adrenal do feto para desencadear o início do parto (figura 2). Figura 2. Mecanismos fetais que controlam o parto em ovelhas. Fonte: LIGGINS et al, 1972. No final da gestação, o feto maduro apresenta um aumento da concentração de corticosteroides plasmáticos devido ao efeito estimulante da hormona adrenocorticotróide (ACVH) secretada pela hipófise fetal sobre as glândulas adrenais do feto. Os corticosteroides fetais por sua vez estimulam as enzimas placentárias para transformar a progesterona em estrogênio. O resultado final é a diminuição dos níveis de progesterona ao mesmo tempo que se eleva a concentração de estrogênios que, por sua vez, estimulam a libertação de PGF2a responsável pelas contrações uterinas. Este raciocínio explica algumas doenças caracterizadas por gestação prolongada em ovelhas, como ocorre na África do Sul, onde estes animais são obrigados, durante as épocas de seca, a ingerir as folhas de um arbusto chamado Salsola tuberculate. O prolongamento da gestação ocorre quando estas folhas são ingeridas durante o último terço da gestação cujos efeitos estão relacionados com a supressão do eixo hipotálamo-hipófise, com o qual as adrenais não recebem o estímulo necessário (ACTH) para a síntese e liberação de corticoides. O efeito contrário é observado nas cabras da raça Angorá, nas quais se produzem, com relativa frequência, partos prematuros que podem estar relacionados com um desenvolvimento precoce das glândulas adrenais. Isto significa que, nos animais domésticos, o feto determina a data do parto. O sinal hormonal que indica à mãe o grau de maturidade do feto é o desenvolvimento do eixo hipotálamo-hipófise-adrenal que origina o aumento na secreção de corticoides fetais que são os responsáveis por desencadear as alterações hormonais no organismo materno necessárias para iniciar o parto. A figura 2 mostra como a remoção da hipófise e as adrenais do feto prolongam a gestação, enquanto a administração exógena de ACTH ou corticoides (cortisol) ao feto originam um parto prematuro. O momento em que ocorre o aumento da concentração plasmática de corticoides no feto varia de acordo com a espécie: de 25 a 30 dias antes do parto na vaca, de 7 a 10 dias na porca e de 2 a 3 dias na ovelha. 2.3 Desenvolvimento e fases do parto O parto inicia-se com o início das contrações peristálticas e regulares do miométrio uterino ao mesmo tempo que o colo do útero se dilata progressivamente. Nas fêmeas que gestam um único feto (monotecas), as contrações começam na extremidade anterior do córneo uterino, enquanto que nas espécies que gestam vários fetos (politocas) as contrações começam pela extremidade cervical para começar a expulsar o feto que se encontra mais próximo do cérvix. Durante o parto são reconhecidas três fases: 1. Fase preparatória - Na qual as contrações uterinas estimulam a rotação do feto (fêmeas monotecas) para adotar a posição dorsal (extremidades anteriores e cabeça forçadas contra o cérvix) que lhe permite oferecer a menor resistência para sua expulsão. A PGF2a provoca as contrações miometriais e a dilatação do cérvix, deslocando o feto contra e através desta estrutura. 2. Fase de expulsão - A passagem do feto através do colo uterino e da vagina causam a completa dilatação destas estruturas, originando a secreção de oxitocina (reflexo de Ferguson), que provoca contrações de maior frequência e intensidade. Por sua vez, estas contrações uterinas são reforçadas pela pressão e contração dos músculos abdominais, chegando estes últimos a ser a força principal (forças de expulsão) envolvida no processo de expulsão do feto. O cordão umbilical rompe-se bem ao levantar-se a mãe ou pelos movimentos do recém-nascido. 3. Fase de expulsão da placenta - Após o parto, as contrações rítmicas do útero continuam a facilitar a expulsão da(s) placenta(s). O tempo necessário para este processo varia de acordo com a espécie animal. Este processo é rápido na égua, já que a separação do corion (membrana fetal) de sua inserção uterina ocorre durante a expulsão do feto, com o qual o parto deve ser concluído rapidamente ou, caso contrário, o potro se asfixiaria. Nos ruminantes, a expulsão da placenta cotiledonaria é um processo mais lento que exige a separação dos cotilédones (membrana fetal) das carúnculas do útero. Por conseguinte, a troca de nutrientes e oxigênio entre a mãe e o feto continua até que este tenha sido totalmente expelido, devido ao cordão umbilical destes animais ser bastante longo. Nas fêmeas politocas, como a porca, geralmente as placentas de vários leitões são expulsadas no final, quando os leitões já foram expelidos, se bem que o último leitão poderá ser expelido durante a expulsão da massa placentária. 3. LACTAÇÃO A lactação constitui o processo que define os mamíferos como classe biológica. O desenvolvimento pós-natal dos mamíferos vai depender, em grande medida, dos nutrientes e defesas fornecidos pela mãe através da secreção de leite (imunoglobulinas). Assim, uma vez concluído o desenvolvimento gestacional do feto, a glândula mamária irá substituir, de certa forma, a função nutritiva e protetora da placenta durante a gestação. 3.1 Anatomia funcional da glândula mamária A estrutura funcional da glândula mamária é muito semelhante em todos os mamíferos, embora o tamanho, forma e número de glândulas varia dependendo da espécie animal. As glândulas mamárias desenvolvem-se como estruturas pares cujo número varia de um par (égua, cabra e ovelha), dois pares (vaca) até sete ou nove (porca). A localização das glândulas também difere sendo inguinal em vaca, égua, cabra e ovelha, enquanto que na porca, cadela e gata se estendem por todo o comprimento do tórax e abdômen. Nos animais domésticos em geral as glândulas mamárias recebem o nome de úberes. Tomando como modelo a vaca, a glândula mamária se organiza em duas estruturas: o estroma, formado por tecido conjuntivo procedente dos ligamentos suspensório medial, localizado entre os dois pares de glândulas, dando suporte à segunda estrutura que é o tecido secretor. Este é formado por acúmulos de células secretoras formando estruturas ocas chamadas alvéolos, que são as unidades fundamentais secretoras de leite. Os alvéolos estão circulados internamente por células epiteliais (secretoras) e rodeados externamente por células mioepiteliais contráteis, cuja contração origina a ejeção do leite (figura 3). O agrupamento de vários alvéolos adjacentes formam um lobo secretor. Figura 3. Diagrama de um agregado de alvéolos na glândula mamária de uma cabra. Fonte: COWIE et al, 1980. Os lobos expelem a secreção através de ductos que, por sua vez, drenam os ductos galactóforas (ductos lácteos) de maior diâmetro, para desembocar em áreas especializadas em armazenar o leite chamadas cisternas (vaca, cabra). Finalmente, a cisterna abre-se para o exterior através do canal papilar da teta. A presença do músculo liso na teta permite-lhe agir como esfíncter para impedir que o leite seja expelido passivamente do interior da glândula. O mamilo/teta é provido de numerosos receptores sensitivos cuja excitação durante a ordenha ou amamentação vai desencadear estímulos nervosos de grande importância para a manutenção da lactação. 3.2 Desenvolvimento da glândula mamária (mamogênese) A glândula mamária difere das demais glândulas do organismo no escasso desenvolvimento que apresenta no nascimento da fêmea, o qual não se inicia até que esta não atinja a puberdade. O início da atividade cíclica do ovário (puberdade) dá origem à síntese de estrogênios (fase folicular do ciclo estral) e progesterona (fase lútea). Os estrogênios originam o alongamento e ramificação dos ductos e a formação de pequenas massas esféricas de células (os futuros alvéolos). Embora este desenvolvimento seja dependente do estrogênio, é também necessária a ação sinérgica da prolactina, hormona do crescimento (GH) e corticoides adrenais, como demonstrado pelos estudos realizados em ratos aos quais foi removida a hipófise, glândulas suprarrenais e ovários (figura 4). A função da progesterona no desenvolvimento da glândula mamária é estimular o crescimento do lobo-alveolar, mas como no caso anterior também requer a ação conjunta dos hormônios acima mencionados. Figura 4. Hormonas relacionadas com o crescimento da glândula mamária e início da secreção de leite na rata hipofisectomizada-adrenoectomizada-ovariectomizada. Fonte: COWIE, 1980. O desenvolvimento da glândula, durante cada ciclo estral, vai depender da duração da fase folicular (níveis elevados de estrogênio), já que nas restantes fases do ciclo, quando os níveis de estrogênio são baixos, os ductos sofrem uma ligeira regressão. Nas espécies com ciclos curtos (rata), em que a fase folicular do ciclo é predominante, enquanto a fase lútea é quase inexistente, verifica-se um grande desenvolvimento dos ductos; enquanto que aquelas que apresentam um corpo lúteo funcional de longa duração (cadela e primatas), além do crescimento dos ductos, mostram um grande desenvolvimento lóbulo-alveolar semelhante ao que ocorre na gestação. É durante a gestação que o sistema alveolar sofre uma hipertrofia considerável, resultando em lobos proeminentes e no desenvolvimento da luz interna dos alvéolos, fato que é evidente na maioria dos animais domésticos por volta da metade do período gestacional. Em algumas espécies, as células que circundam interiormente os alvéolos contêm produtos secretores, indicando que a glândula mamária já está preparada para a fase da lactação. O desenvolvimento glandular durante a gestação deve-se ao efeito conjunto da progesterona e dos estrogênios com as hormonas hipofisárias acima mencionadas: prolactina, hormona do crescimento (GH) e adrenocorticotropina (ACTH). A proporção entre estrogênios e progesterona varia de acordo com a espécie, mas geralmente é necessária uma maior concentração de progesterona (proveniente do corpo lúteo ou da placenta). Quanto às hormonas hipofisárias, a prolactina desempenha um papel fundamental na diferenciação da glândula mamária (mesmo a baixas concentrações) ao estimular o desenvolvimento do epitélio secretor dos alvéolos. A GH favorece o crescimento dos ductos e a ACTH estimula a secreção de corticoides nas adrenais que, por sua vez, favorecem de forma generalizada o crescimento das glândulas. 3.3 Secreção da glândula mamária (lactogênese) A lactogênese, ou o processo pelo qual se produz a síntese e secreção do leite pela glândula mamária, começa no final da gestação coincidindo com o desencadeamento do parto. O primeiro leite formado imediatamente antes ou depois do parto é denominado colostro. No entanto, a lactação não pode desenvolver- se completamente até que se inicie o processo de parto. Isto deve-se ao fato de que o processo de lactação resulta de uma interação complexa de hormonas que preparam a glândula mamária para a secreção do leite. Os requisitos hormonais mínimos para o início da lactogênese são: aumento da secreção de estrogênios, prolactina e corticoides, juntamente com a diminuição da concentração de progesterona, perfis hormonais que estão intimamente relacionados com o desencadeamento do parto. Isto deve-se ao fato de que a progesterona inibe a atividade lactogênica da prolactina bloqueando a formação dos seus receptores na glândula mamária durante a gestação impedindo, assim, a prolactina de sintetizar os componentes fundamentais do leite. Pelo contrário, o aumento da concentração de estrogênios no final da gestação (figura 1, na seção do parto) estimula a síntese, o armazenamento e a secreção hipofisária de prolactina. Assim, apesar da glândula mamária estar preparada para iniciar a secreção de leite, muito antes da data prevista para o parto, a elevada concentração de progesterona (existente durante esse período de gestação) impede a fase láctea (saída do leite pelas tetas) de ocorrer antes da expulsão do feto. Desta forma, o feto poderá beneficiar das vantagens que o fornecimento do colostro materno irá trazer para a sua sobrevivência (imunização, nutrição e favorecimento da exoneração do mecônio). O aumento da concentração de estrogênios nos dias que antecederem o parto resulta num rápido aumento das concentrações plasmáticas de prolactina e corticoides. A prolactina é a hormona lactogênica mais importante na síntese dos componentes do leite. No entanto, para que esta hormona possa exercer a sua função, é necessária a participação dos corticoides, já que os mesmos são os responsáveis pelo desenvolvimento das organelas citoplasmáticas (retículo endoplasmático rugoso e aparelho de Golgi) onde se realiza a síntese do leite. No desenvolvimento da lactogênese, para além da prolactina e dos corticoides, participam também outras hormonas como a insulina, a tiroxina e o hormônio do crescimento. A insulina estimula a proliferação de novas células epiteliais na glândula mamária, enquanto a tiroxina, embora não seja essencial para a lactação, pode influenciar no volume de leite produzido pela fêmea (alta produção leiteira). Por último, a hormona do crescimento favorece, em geral, a lactação, existindo atualmente um interesse considerável no uso desta hormona para promover a produção adicional de leite em vacas através da sua administração exógena (trabalho e projeto desenvolvido pela professora titular e médica-veterinária do IFPB Campus Sousa Marianne Christina Velaqua). 3.3.1 Síntese e secreção dos componentes do leite Os principais constituintes do leite são: proteínas (caseína, alfa-lactalbumina, albumina sérica e imunoglobulinas), açúcares (lactose), gorduras (principalmente sob a forma de triglicerídeos), vitaminas, minerais e citrato (no caso dos ruminantes). As proteínas (caseína e alfa-lactalbumina) são sintetizadas no retículo endoplasmático rugoso e posteriormente embaladas em vesículas secretoras do aparelho de Golgi para serem liberadas da célula para a luz alveolar mediante um processo de exocitose. A lactose é o principal açúcar do leite que, além disso, atua regulando a pressão osmótica do mesmo de modo que o volume de leite que a glândula mamária segrega está diretamente relacionado com a quantidade de lactose presente. A síntese da lactose ocorre no aparelho de Golgi pela condensação de glicose e galactose; esta reação é catalisada por uma enzima (lactose sintetase) presente na membrana do aparelho de Golgi que, por sua vez, é ativada pela proteína alfa-lactalbumina. Esta proteína só aparece na glândula mamária e é essencial para a síntese da lactose, o que demonstra que este açúcar é exclusivamente formado no leite. A lactose é também embalada junto com o cálcio, o fosfato e as proteínas nas vesículas secretoras para ser expulsada ao lúmen alveolar por exocitose. As imunoglobulinas (anticorpos IgA) são formadas pelas células plasmáticas, derivadas dos linfócitos B do sangue, como consequência da exposição da mãe a diferentes microrganismos. Estes anticorpos passam para a glândula mamária por migração dessas células a partir dos tecidos adjacentes. Os triglicerídeos são sintetizados no citoplasma e no retículo endoplasmático liso a partir de ácidos graxos provenientes da circulação sanguínea; em seguida, unem-se formando glóbulos de gordura que se dirigem até o vértice da membrana plasmática para serem finalmente expelidos para a luz do alvéolo, rodeados pela membrana, formando assim uma dispersão de glóbulos de gordura (figura 5). Figura 5. Estrutura de três células alveolares durante a síntese do leite. Fonte: COWIE, 1980. Do ponto de vista quantitativo, a caseína e os triglicerídeos constituem as proteínas e as fontes de energia, respectivamente, mais importantes do leite. Por último, o citrato é um intermediário do metabolismo da glicose que ocorre em grande concentração no leite dos ruminantes. Este composto é também englobado no interior das vesículas secretoras, junto com os outros compostos, para sua expulsão à luz alveolar. A composição do leite varia dependendo da espécie animal, e difere também até entre a mesma espécie. Estas variações estão relacionadas com a raça, idade, estágio de lactação e estado nutricional do animal. O teor de gordura no leite de ovelhas, porcas, cadelas e gatas varia entre 7 e 10%. No gado leiteiro estes valores variam de 3,5 a 5,5%, dependendo da raça. Em relação às cabras, os valores de gordura são muito semelhantes aos das vacas, enquanto o leite das éguas é o que tem menor teor de gordura (tabela 1). Espécie Gordura Proteína Lactosa Cinzas/Cálcio Gata 7,1 10,1 4,2 0,5 Vaca holandesa 3,5 3,1 4,9 0,7 Cadela 9,5 9,3 3,1 1,2 Cabra 3,5 3,1 4,6 0,8 Égua 1,6 2,4 6,1 0,5 Tabela 1. Composição do leite em várias espécies (%). Fonte: JACOBISON, 1984. 3.4 Manutenção da lactação (galactopoiese) A capacidade da glândula mamária de secretar um grande volume de leite começa em/ou imediatamente antes do parto, para aumentar no período pós-parto durante um tempo variável e, posteriormente, diminuir de forma gradual. Em geral, existe um paralelismo entre a atividade secretora da glândula e a procura de leite por parte do lactente. Isto deve-se ao fato de sucção pelo lactente, ou a extração por ordenha, que constituem o fator fundamental para a manutenção da lactação. A sucção estimula a lactação de duas formas: a) reduzindo os efeitos inibitórios da pressão intramamária produzida pela acumulação de leite, e b) estimulando intensamente a secreção de hormonas necessárias para manter a síntese e secreção de leite nos alvéolos. As hormonas que desempenham um papel fundamental na manutenção da lactação são: I) a prolactina, que é responsável pela estimulação da síntese e secreção de leite nas células epiteliais nos alvéolos, e 2) a oxitocina, que provoca a contração das células musculares que circundam externamente os alvéolos e os ductos (células mioepiteliais). A libertação de ambos os hormônios ocorre como resultado de um reflexo neuroendócrino originado pela estimulação do mamilo. 3.4.1 Secreção reflexa de prolactina A secreção de prolactina é regulada por dois fatores hipotalâmicos: a dopamina, que inibe a secreção de prolactina e um fator cuja identidade não está bem definida, conhecido como fator liberador de prolactina (PRF)que estimula a liberação deste hormônio. O estímulo sensorial originado como sequência da estimulação do mamilo, pela sucção do lactente, é transportado através da medula espinhal para o hipotálamo, onde atua na inibição da dopamina ou estimulando a secreção do PRF para desencadear a secreção de prolactina da adenohipófise para a circulação sanguínea (figura 6). Figura 6. Reflexos neuroendócrinos secretores de prolactina e oxitocina. Fonte: HAFEZ, 2000. A prolactina estimula a secreção dos componentes do leite para a luz dos alvéolos, afim de repor o volume de leite extraído durante a última ordenha ou sucção. Ao mesmo tempo, a prolactina induz a síntese das proteínas, incluindo a alfa-lactalbumina para estimular novamente a síntese da lactosa, bem como as enzimas necessárias para a produção dos triglicerídeos. Desta forma, a secreção de prolactina originada pelo lactente durante o aleitamento proporciona um mecanismo simples para combinar o volume de produção de leite com as necessidades do lactente. A quantidade de prolactina liberada durante cada período de sucção depende do número de crias, da duração do estímulo e dos intervalos de tempo decorridos entre os períodos de sucção (ou ordenha). No caso das vacas leiteiras, as ordenhas são geralmente realizadas de doze em doze horas, intervalo de tempo suficiente para manter a lactogênese. Os valores plasmáticos de prolactina aumentam imediatamente após o início da ordenha, mas os valores mais elevados são obtidos cerca de meia hora após o início do estímulo (ordenha ou sucção). A secreção de prolactina e a produção de leite são influenciadas de alguma forma pelo fotoperíodo, uma vez que, em alguns animais se comprovou como o aumento do número de horas de exposição à luz dá origem a um aumento da concentração de prolactina circulante, bem como uma maior produção de leite (entre 6 e 10%) (trabalho e projeto elaborado pelos estudantes do curso técnico em agropecuária e da graduação em Medicina Veterinária do IFPB Campus Sousa sob a coordenação e orientação da profa. Me. Esp. Marianne C. Velaqua). 3.4.2 Reflexo da ejeção do leite A sucção do mamilo pelo lactente estimula os receptores sensoriais presentes nesta estrutura, originando a geração de impulsos nervosos que são transmitidos pelas vias nervosas ascendentes da medula espinhal para os corpos celulares produtores de oxitocina no hipotálamo. O estímulo desencadeia a síntese e liberação de um bolo de oxitocina através das terminações nervosas dos núcleos hipotalâmicos para a neurohipófise, da qual é transmitida, através do sangue, para a glândula mamária, provocando a contração das células mioepiteliais que rodeiam os alvéolos (figura 6). Além da estimulação direta do mamilo provocada pela sucção, qualquer estímulo relacionado à ordenha é capaz de gerar o reflexo da ejeção, por exemplo: os estímulos sensoriais auditivos (ruído dos cubos na hora da ordenha), visuais (ambiente da sala de ordenha), táteis (lavagem manual dos mamilos antes da ordenha) e os estímulos olfatórios que se produzem em torno do animal. O desencadeamento do reflexo de ejeção pelos estímulos sensoriais, que não estão diretamente relacionados com a sucção ou ordenha, indica a possível participação de centros superiores do sistema nervoso central para controlar a secreção de oxitocina. Esta teoria é baseada em que os estímulos relacionados com situações de estresse em animais de estimação (medo, ansiedade, frio, etc.) inibem a ejeção do leite. A contração das células mioepiteliais gera um aumento da pressão intra-alveolar mamária, provocando o deslocamento do leite para os ductos maiores da glândula. Este efeito é popularmente conhecido como diminuição do leite e constitui um mecanismo fisiológico muito eficaz para controlar a expulsão do leite para o mamilo, assegurando que a ejeção do leite se realize unicamente quando o lactente o demanda. O efeito estimulante da oxitocina é de grande importância já que a maior parte do leite se encontra nos alvéolos e nos ductos, com o qual, a ausência deste hormônio provocaria um lento movimento do leite para a cisterna do úbere e, portanto, uma menor quantidade de leite. Assim, quando os alvéolos e ductos menores são contraídos, ocorre o relaxamento dos ductos principais, bem como da cisterna (ruminantes) e do mamilo, o que dá origem a um aumento destas estruturas para alojar o volume de leite expelido. Como resultado da volumosa ejeção do leite dos alvéolos e ductos menores, ocorre um aumento da pressão intramamária de modo que o lactente terá que vencer a resistência do esfíncter do mamilo para poder extrair o leite. A produção de leite pela glândula mamária diminui gradualmente à medida que os intervalos de tempo entre os dois períodos de amamentação do lactente diminuem e os estímulos necessários para manter as concentrações de prolactina e oxitocina na circulação sanguínea. A diminuição ou cessação da secreção de leite, geralmente coincide com a mudança na alimentação das crias (desmame) para passar à dieta característica da espécie. 3.5 Colostro O colostro é o primeiro leite que se forma na glândula mamária coincidindo com o parto. A ingestão de colostro por recém-nascidos é de grande importância para a sua sobrevivência, não só pelo seu elevado valor nutritivo, mas também pelo seu teor em imunoglobulinas (IgA) que lhe confere a imunização passiva necessária para o proteger contra patologias. Em algumas espécies (homem, coelho e cobaia) grande parte dos anticorpos passam para a circulação do feto através da placenta durante a gestação. Nos animais domésticos (vaca, égua, ovelha, cabra, porco) as características da placenta (número de camadas entre a circulação materna e fetal) não permitem a passagem destas proteínas. Como resultado, a imunização das crias nestas espécies animais vai depender da transferência das imunoglobulinas através do colostro. O epitélio intestinal dos recém-nascidos permite a passagem destas imunoglobulinas durante as primeiras 24 a 48 horas de vida. Passado este tempo, o epitélio torna-se impermeável à passagem dos anticorpos, fato que põe em evidência a importância que tem para os animais recém-nascidos e desprovidos de defesas a ingestão do colostro durante os primeiros dias. A composição do colostro caracteriza-se (em relação ao leite normal) por um teor mais elevado de proteínas, vitaminas, minerais e uma menor concentração de lactose. A composição do colostro muda gradualmente durante os primeiros três dias após o parto para se transformar em leite normal. 4. RESUMO E PRIMEIRAS CONCLUSÕES O parto, ou processo fisiológico pelo qual se expulsa o feto, é o resultado da maturação sequencial de um sistema de comunicação hormonal. A sequência inicia-se no sistema nervoso central do feto de onde os sinais são transmitidos e amplificados, através da hipófise, para as glândulas adrenais fetais, as quais respondem ao estímulo mediante a secreção de cortisol. O aumento da concentração de cortisol por parte do feto indica que este conseguiu o desenvolvimento necessário para enfrentar a vida extrauterina e, portanto, é hora de interromper a gestação. O cortisol atua sobre a placenta para aumentar a secreção de estrogênios que, por sua vez, estimulam a síntese e a liberação de prostaglandinas. O resultado é a diminuição da progesterona, que é a hormona encarregada de manter a gestação ao inibir as contrações espontâneas do útero, impedindo assim a expulsão prematura do feto. O útero, sob os efeitos da prostaglandina, começa a contrair-se ao mesmo tempo que o colo uterino amolece e dilata progressivamente (fase preparatória do parto). A passagem do feto ao canal do parto origina a secreção reflexa de oxitocina (fase de expulsão), causando contrações de maior frequência e intensidade que culminam com a expulsão do feto. Finalmente, as contrações uterinas continuam durante algum tempo até que finalmente é expulsa a placenta (fase de expulsão da placenta). O desenvolvimento da glândula mamária durante a gestação e a subsequente capacidade desta estrutura para secretar leite, coincidindo com o parto, oferece aos animais pertencentes à classe biológica dos mamíferos a vantagem de alimentar as suas crias para assegurar a sua sobrevivência durante as primeiras fases do seu desenvolvimento e, portanto, a continuidade da espécie. A lactação constitui um dos processos fisiológicos mais complexos em consequência do grande número de hormonas que, segregadas de forma coordenada, controlam as diferentes fases pelo que atravessa este processo: I) mamogênese ou desenvolvimento dos dutos e estruturas lóbulo-alveolares durante a gestação; 2) lactogênese ou síntese láctea por células epiteliais e sua secreção para a luz alveolar coincidindo com o parto, e 3) galactopoiese ou manutenção da síntese e secreção do leite como consequência da sua extração da glândula mamária seja pela sucção da cria ou pela ordenha. -/- Emanuel Isaque Cordeiro da Silva – Departamento de Zootecnia da UFRPE. Recife, 2020. -/- REFERÊNCIAS BIBLIOGRÁFICAS -/- BEIGHLE, D. E. The effect of gestation and lactation on bone calcium, phosphorus and magnesium in dairy cows. Journal of the South African Veterinary Association, v. 70, n. 4, p. 142-146, 1999. BRACKELL, B. G.; JR SEIDEL, G. E.; SEIDEL, S. Avances en zootecnia nuevas técnicas de reproducción animal. Zaragoza: Acribia, 1988. COLE, H. H.; CUPPS, P. T. Reproduction in domestic animals. 1ª ed. Londres: Academic Press, 1977. COWIE, Alfred T.; FORSYTH, Isabel A.; HART, Ian C. Lactation. In: Hormonal control of lactation. Springer, Berlin, Heidelberg, 1980. p. 146-229. CUNNINGHAM, James G. Fisiología veterinaria. São Paulo: Elsevier, 2003. DERIVAUX, Jules; BARNABÉ, Renato Campanarut. Reprodução dos animais domésticos. Zaragoza: Acribia, 1980. DA SILVA, Emanuel Isaque Cordeiro. Definição de Conceitos Básicos na Reprodução Animal: Fertilidade, Fecundidade e Prolificidade-Suínos. Philarchive. Disponível em: -----. Acesso em: Fevereiro de 2020. DA SILVA, Emanuel Isaque Cordeiro. Características Gerais dos Bovinos/General Characteristics of Cattle Bovine. Philarchive. Disponível em: -----. Acesso em: Fevereiro de 2020. DA SILVA, Emanuel Isaque Cordeiro. Reprodução Animal: Fecundação e Gestação. Disponível em: Acervo IFPE. Acesso em: Março de 2020. FERNÁNDEZ ABELLA, Daniel Héctor. Principios de fisiología reproductiva ovina. Montevidéu: Hemisferio Sur1993. GONZÁLEZ, Félix HD. Introdução a endocrinologia reprodutiva veterinária. Porto Alegre: UFRGS, v. 83, 2002. HAFEZ, E. S. E.; HAFEZ, B. Reprodução animal. São Paulo: Manole, 2004. HAFEZ, Elsayed Saad Eldin; HAFEZ, B. (Ed.). Reproduction in farm animals. Nova Jersey: John Wiley & Sons, 2013. HUNTER, R. H. F. Reproducción de los animales de granja. Zaragoza: Acribia, 1987. HUNTER, Ronald Henry Fraser et al. Physiology and technology of reproduction in female domestic animals. Londres: Academic Press, 1980. ILLERA, M. Endocrinología Veterinaria y Fisiología de la Reproducción. Zaragoza: Fareso, 1994. JACOBSON, N. L.; MCGILLIARD, A. D. The mammary gland and lactation. Duke’s Physiology of Domestic Animals. 10th edition. Comstock Publishing Associates, Cornell University Press, Ithaca, New York, USA, p. 863-880, 1984. JAINUDEEN, M. R.; HAFEZ, E. S. E. Gestação, fisiologia pré-natal e parto. Revista Brasileira de Reprodução animal, v. 7, p. 141-142, 2004. LIGGINS, G. C. et al. physiological roles of progesterone, oestradiol-17beta and prostaglandin F2alpha in the control of ovine parturition. J Reprod and Fert Suppl, 1972. PÉREZ PÉREZ, F.; PÉREZ GUTIÉRREZ, F. Reproducción animal, inseminación animal y transplante de embriones. Barcelona: Cientifico-medica, 1985. ROBERTS, Stephen J. Obstetricia veterinaria y patología de la reproducción. Montevidéu: Hemiferio Sur, 1979. SALISBURY, G. W.; VANDERMARK, N. L. Phisiology of the reproduction and artificial insemination of cattle. San Francisco : Freeman e Company, 1961, 630 p. SHILLE, V. M. Fisiologia reprodutiva e endocrinologia da fêmea e do macho. Tratado de medicina interna veterinária. São Paulo: Manole, p. 1857-68, 1992. RUTTER, Bruno; RUSSO, Angel F. Fundamentos de la fisiología de la gestación y el parto de los animales domésticos. Buenos Aires: Eudeba, 2002. UNGERFELD, Rodolfo. Reproducción en los animales domésticos. Montevidéu: Melibea, 2002. (shrink)

TRANSPORTE DE GAMETAS, FERTILIZAÇÃO E SEGMENTAÇÃO -/- • _____OBJETIVO -/- O entendimento do desenvolvimento embrionário nos estágios iniciais, desde a deposição dos espermatozoides na fêmea, passando pela fertilização deste no ovócito e na formação do zigoto, é de suma importância para diferenciar especialistas em reprodução e manejo reprodutivo no mercado de trabalho e, também, durante a vida acadêmica. Compreender os processos que levam à formação do zigoto na fêmea é essencial para avaliar a capacidade reprodutiva dos animais e, mediante técnicas, (...) avaliar o trato reprodutivo da fêmea e o desenvolvimento do embrião até a formação do feto e, por fim, em um novo animal sadio na propriedade. Com esse trabalho, o estudante de veterinária ou zootecnia, que deseja se aprofundar na fisiologia da reprodução animal, identificará os mecanismos que são envolvidos no transporte dos gametas, bem como os processos que estes últimos devem completar para alcançar a fertilização e para desencadear as divisões iniciais do embrião. -/- • _____INTRODUÇÃO -/- A fertilização ou fecundação é o processo pelo qual os gametas masculino (espermatozoide) e feminino (ovócito) se fundem para gerar um novo indivíduo. Seu êxito depende da culminação adequada dos diferentes processos que devem sofrer os gametas durante sua maduração e percurso; do transporte oportuno destes no trato reprodutivo da fêmea, assim como de uma série de adaptações dos órgãos genitais internos da mãe. A segmentação refere-se às primeiras divisões celulares do embrião. -/- • _____TRANSPORTE DO OVÓCITO -/- O ovócito que é liberado na ovulação, e que se encontra coberto pelas células do cumulus (figura 1), é capturado pela fímbria do infundíbulo ao aderir aos cílios. Esse processo é altamente eficaz, inclusive em espécies onde os ovários possuem várias formações globosas, por exemplo nas porcas, onde os ovidutos capturam entre 95 e 100% dos ovócitos que são ovulados. As contrações das camadas musculares do oviduto e o movimento intenso dos cílios da mucosa faz com que as secreções fluam em direção ao útero, transportando assim o complexo cumulus-ovócito. Esse transporte é relativamente rápido até alcançar a junção da ampola com o istmo (que é considerado o local de fertilização do espermatozoide e ovócito) a partir do qual se torna lento. Devido a fêmea estar em estro, o processo está sob controle endócrino, isto é, controle hormonal através do estradiol. Nas fêmeas domésticas, ao contrário das mulheres, o transporte ao longo do oviduto é extremamente eficiente, pois os embriões passam para o útero sem dificuldade, de modo que gestações ectópicas (tubárias ou em cavidade) são quase inexistentes. A égua, frequentemente, retém por muito tempo os ovócitos não fertilizados no oviduto, provavelmente devido a não secreção de substâncias (como a prostaglandina E) que poderiam favorecer sua passagem, como se propõe que aconteça com os embriões. A figura 2 apresenta um ovócito com suas respectivas estruturas. Figura 1: ovócitos de uma vaca madurados in vitro. Nota-se as células do cumulus que os recobre. -/- Figura 2: estruturas do ovócito de uma ovelha que se encontra na etapa de ovócito secundário, depois da ovulação. Elaborado pelo autor. • _____TRANSPORTE ESPERMÁTICO -/- Para que os espermatozoides sejam capazes de fertilizar o ovócito, deverão sofrer uma série de mudanças bioquímicas e morfológicas ao longo de sua passagem pelo aparelho reprodutor tanto masculino como feminino. Uma vez produzidos na parede do túbulo seminífero, os espermatozoides são liberados em direção ao lúmen tubular e transportados passivamente para uma estrutura ramificada conhecida como rede testicular (rete testis). Dessa rede são conduzidos em direção ao epidídimo passando através de 10 a 20 ductos eferentes localizados no polo superior do testículo. O epidídimo é dividido em três seções denominadas cabeça, corpo e cauda; é constituído por um só ducto longo e tortuoso que continua com o canal deferente. Ao final desemboca nas ampolas seminais, no ducto ejaculatório e na uretra. As funções do epidídimo são as de maduração, transporte e armazenamento dos espermatozoides. O transporte através do epidídimo é lento, aproximadamente de 10 dias em touros, e segue sendo passivo. Os espermatozoides tomados da cabeça do epidídimo são ainda imaturos e incapazes de fertilizar, enquanto os armazenados na cauda são completamente maduros. Durante o trânsito pelo epidídimo os espermatozoides adquirem motilidade e o potencial para fertilizar, o acrossomo é remodelado e a gota citoplasmática migra para o flagelo e é liberada. Quando um macho ejacula com muita frequência, é possível observar espermatozoides com gota citoplasmática no sêmen, já que não há tempo suficiente para que completem sua maduração. Os espermatozoides são expulsados fora do organismo durante a cópula, na masturbação ou em emissões espontâneas. Na ejaculação, os espermatozoides que se encontram suspensos nos fluidos do testículo e do epidídimo, misturam-se ao chegar na uretra com as secreções das glândulas acessórias para formar o sêmen. Essas secreções denominadas plasma seminal, proporcionam substâncias para manter o metabolismo energético das células espermáticas, e integram suas membranas elementos que impedem uma capacitação prematura. Durante a cópula, o sêmen é depositado na vagina ou no útero, variando entre as espécies (tabela 1). Na monta natural, geralmente, o serviço ocorre no momento propício, já que está definido pela fase do ciclo estral em que a fêmea é receptiva ao macho. No entanto, na inseminação artificial, é o macho que deverá determinar o momento ideal, e para isso é importante considerar a vida média dos gametas, ao qual é muito curta no caso dos ovócitos (tabela 1). -/- Tabela 1: local de depósito do sêmen, volume da ejaculação e vida média dos gametas. Espécie Local de deposição Volume (ml) Velocidade de ejaculação Vida média do ovócito Vida média do espermatozoide Bovinos Intravaginal 2 1 – 3 seg 8 h 30 – 48 h Caninos Intravaginal 2 – 30 (10 média) 6 – 45 min 48 – 72 h 9 – 11 d Equinos Intrauterina 50 – 200 20 – 60 seg 6 – 8 h 72 – 120 h Humanos Intravaginal 3 - - 5 – 6 d Ovinos Intravaginal 1 1 – 2 seg 16 – 24 h 30 – 48 h Suínos Intrauterina 200 – 400 5 – 20 min 8 – 10 h 24 – 48 h Onde d = dias; h = horas. A vida fértil do ovócito é muito curta, portanto, o momento do serviço é de grande importância para obter altos índices de fertilização. -/- Independentemente do local em que os espermatozoides sejam depositados no aparelho reprodutor feminino, serão expostos às secreções genitais e sofrem uma série de mudanças em seu trajeto até o local de fertilização antes de penetrar no ovócito. Nas espécies em que o sêmen é depositado na parte cranial da vagina, uma parte do mesmo penetra através da cérvix, enquanto outra parte é eliminada do aparelho genital da fêmea, em pouco tempo, através do fluxo retrógrado. O meio vaginal não é adequado e imobiliza os espermatozoides em pouco tempo, pelo qual deverão entrar no útero onde o ambiente é mais propício. O transporte espermático na fêmea é o resultado da alta contratilidade, do movimento ciliar e o fluido do aparelho genital durante o estro, ao qual está sob controle endócrino e do sistema nervoso. Esse transporte é favorecido pelas características especiais do muco estral, cujas moléculas formam uma espécie de canais que facilitam a passagem dos espermatozoides. Pelo contrário, durante a fase lútea seu transporte é dificultado. Além do meio vaginal, a cérvix também atua como barreira natural para limitar a passagem dos espermatozoides, diminuindo assim a possibilidade de polispermia. Funciona, também, como um filtro que seleciona os espermatozoides aptos dos que não o são, uma vez que somente os primeiros possuem uma motilidade vigorosa que lhes permite passar pelo muco altamente hidratado. Na vaca a cérvix é considerada como um reservatório espermático. Quando atravessam a cérvix, os espermatozoides seguem sua deslocação tanto por movimento próprio como pelas contrações uterinas e tubárias. Nas espécies em que o local de depósito do sêmen do macho na fêmea é intrauterino, como equinos, a principal barreira que os espermatozoides enfrentam é a união ou junção útero-tubárica. A união entre o útero e o oviduto (istmo do oviduto) serve como reservatório funcional dos espermatozoides nas espécies domésticas. Poucos minutos depois da cópula, é possível encontrar alguns espermatozoides no oviduto, que é conhecido como fase de transporte rápido. No entanto, esses espermato-zoides não são os que participam do processo de fertilização e podem apresentar certas anormalidades. Existe um segundo tipo de transporte denominado fase sustentada, a qual consiste na migração prolongada dos espermatozoides em direção as partes mais craniais do aparelho genital feminino, que conduzem à colonização do reservatório funcional e na liberação gradual dos espermatozoides dos reservatórios espermáticos, incluindo este último. O reservatório do istmo fornece aos espermatozoides um ambiente propício, protegendo-os contra a fagocitose, prolongando assim a sua viabilidade. Aqui os esper-matozoides permanecem aderidos a superfície das células ciliadas do epitélio até a finalização de sua capacitação, depois da qual são liberados quando alteram seu padrão de motilidade flagelada, fenômeno conhecido como hipermotilidade, e migram em ondas em direção ao local da fertilização. Dos milhões de espermatozoides ejaculados, somente alguns milhares alcançarão o istmo do oviduto e um número sumamente pequeno será encontrado nas imediações do ovócito no momento da fertilização. -/- • _____CAPACITAÇÃO ESPERMÁTICA E REAÇÃO ACROSSÔMICA -/- A capacitação é um processo gradual e essencial para a fertilização. Os espermato-zoides devem passar por um dado tempo de “incubação” no aparelho genital da fêmea e sofrer uma série de mudanças antes de serem capazes de fecundar o ovócito. A capacita-ção dos espermatozoides começa quando eles entram em contato com as secreções do aparelho genital da fêmea e termina no istmo do oviduto. Durante esse percurso a superfície da cabeça do espermatozoide se modifica já que algumas moléculas como o colesterol são removidas da membrana plasmática, aumentando sua fluidez e alterando suas propriedades bioquímicas. Entre outras coisas, essa reorganização dos lipídios facilita a entrada de cálcio extracelular pelos canais iônicos e ocasiona a desestabilização da membrana, tornando-a mais fusogênica. Também são eliminados outros fatores (conhecidos genericamente como fatores descapacitantes) que expõem receptores membranais indispensáveis para a realização da união entre o espermatozoide e o ovócito durante a fertilização. Os espermatozoides capacitados apresentam um padrão de hipermotilidade e uma maior atividade metabólica, características que devem obter para que sejam capazes de penetrar as camadas do ovócito. A capacitação é necessária para que ocorra a reação acrossômica. A reação acrossomal ou acrossômica (RA) é um fenômeno de exocitose que é desencadeada pela ligação entre as proteínas e receptores localizados na membrana do espermatozoide e a zona pelúcida do ovócito (figura 3). Envolve a fusão da membrana plasmática do espermatozoide com a membrana externa de seu acrossomo; formando, assim, pequenas vesículas, cujo conteúdo de enzimas hidrolíticas, como a hialuronidase e a acrosina, é liberado em direção ao seu exterior, facilitando a penetração da zona pelúcida. A adesão do espermatozoide à zona pelúcida é específica da espécie e depende de glicoproteínas presentes na membrana dos ovócitos maduros; a cabeça do espermatozoide se une com essas glicoproteínas mediante receptores específicos e atravessam em direção oblíqua a zona pelúcida até chegar ao espaço perivitelino. Nos mamíferos, particularmente em roedores e nos humanos, algumas dessas glicoproteínas são conhecidas como ZP1, ZP2 e ZP3. Pensa-se que a união da membrana espermática a esta última é o que desencadeia a reação acrossomal. Posteriormente, as vilosidades do ovócito entram em contato com o espermatozoide e a membrana presente na secreção equatorial da cabeça do espermatozoide, que tem proteínas fusogênicas específicas, une-se a membrana plasmática do ovócito, fusionando-se e permitindo a entrada do núcleo espermático ao citoplasma (figura 4). A capacitação dos espermatozoides é fundamental para o êxito da fertilização, uma vez que apenas os aptos estarão perfeitos e íntegros para que a união e percepção das glicoproteínas presentes nos mesmos possam ocorrer de forma ideal para a penetração deste no ovócito, fertilizá-lo e formar um zigoto. Figura 3: estrutura do espermatozoide. Nota: a membrana é acrossomal e não acrossonal. Elaborado pelo autor. -/- Figura 4: eventos que ocorrem durante a fertilização. A – depois de passar através das células do cumulus, o espermatozoide entra em contato com a zona pelúcida, onde receptores da membrana plasmática reconhecem as proteínas da zona pelúcida; B – é desencadeada, então, a reação acrossomal; C – para que o espermatozoide penetre na zona pelúcida; D – ao atravessar a zona pelúcida e entrar no espaço perivitelino, a cabeça do espermatozoide entra em contato com a membrana vitelina; ambas membranas se fusionam graças ao reconhecimento de proteínas fusogênicas que estão no segmento equatorial. E – ocorre, então, que o núcleo do espermatozoide penetra no citoplasma do ovócito; uma das consequências da fusão da membrana com a cabeça do espermatozoide é a reação cortical, em que os grânulos corticais do ovócito liberam seu conteúdo em direção ao espaço perivitelino, o que resulta na alteração da estrutura da zona pelúcida e da membrana vitelina para bloquear a polispermia. Elaborado pelo autor. • _____CONSEQUÊNCIAS DA PENETRAÇÃO -/- Bloqueio da polispermia -/- A fusão das membranas dos gametas durante a penetração permite a entrada da fosfolipase C zeta (PLCζ) – fator solúvel que provém do espermatozoide – que desencadeia liberação e oscilações de Ca2+ no retículo endoplasmático. Isso, por sua vez, provoca a migração e fusão dos grânulos corticais, com a consequente liberação de enzimas, que mudam tanto a estrutura da zona pelúcida (por exemplo a inativação de ZP3), como a da membrana vitelina. Desse modo, impede-se que outros espermatozoides as penetrem, evitando assim a polispermia (figura 5). -/- Figura 5: os grânulos corticais que encontram-se na periferia do citoplasma, debaixo da superfície da membrana do ovócito, migram e fusionam-se sobre a mesma, liberando seu conteúdo no espaço perivitelino imediatamente depois da penetração do espermatozoide. A – como conse-quência, tanto a membrana vitelina como a zona pelúcida são modificadas, impedindo a entrada de mais espermatozoides, o que evita a polispermia. B – o ovócito retoma, então, sua segunda divisão meiótica, que ocasiona a expulsão do segundo corpúsculo polar, e na formação dos pronúcleos feminino e masculino. C – continuando, os pronúcleos migram, suas membranas se dissolvem e os cromossomos de ambos se condensam e se unem. Completa-se, assim, a singamia e forma-se, então, o zigoto. Elaborado pelo autor baseado nos livros de embriologia e fisiologia da reprodução conforme vida bibliografia. -/- Ativação do ovócito e formação de pronúcleos -/- Na maioria das fêmeas domésticas, com exceção da cadela, o ovócito encontra-se suspenso na metáfase II da segunda meiose no momento da ovulação. A entrada da PLCζ do espermatozoide no citoplasma do ovócito, e a consequente liberação de Ca2+, faz com que o ovócito se ative, terminando a segunda divisão meiótica e expulse o segundo corpo polar. Posteriormente, o material nuclear do ovócito se reorganiza para formar o pronú-cleo feminino. Entretanto, a membrana nuclear do espermatozoide se dissolve, a cromatina descondensa-se, as protaminas são substituídas por histonas, e se forma uma nova membrana nuclear, dando lugar ao pronúcleo masculino. -/- Singamia -/- Uma vez que os pronúcleos feminino e masculino são formados, migram para o centro do ovócito, aproximam-se, suas membranas se dispersam e os cromossomos paternos e maternos se associam, com o qual recupera a condição diploide e dá origem ao zigoto (figura 5). -/- • _____DESENVOLVIMENTO EMBRIONÁRIO -/- Poucas horas após a fertilização ocorre a primeira divisão do zigoto em duas, depois em 4, 8, 16 e 32 células, denominadas blastômeros. Essas divisões mitóticas são conhecidas como divisões de segmentação ou clivagem (figura 6), uma vez que são realizadas sem aumento do citoplasma, de modo que com cada divisão os blastômeros se tornam menores. A partir das 16 células o embrião se chama mórula, e é visto como uma massa celular compacta. A compactação deve-se a informação de proteínas de ligação entre os blastômeros. O embrião acumula líquido em seu interior, formando uma cavidade denominada blastocele. Esse processo é conhecido como blastulação; o embrião, assim, passa a ser chamado de blastocisto. Nessa etapa é possível diferenciar duas populações de células embrionárias: a massa celular interna, embrioblasto ou botão embrionário (que dará origem ao embrião), e a massa celular externa, células superficiais ou trofoblasto, do qual se originam a maioria das membranas fetais. Ao continuar a multiplicação das células e a acumulação de líquido, o blastocisto aumenta de tamanho, convertendo-se em blastocisto expandido. A zona pelúcida torna-se mais fina e, finalmente, o embrião eclode; isto é, o embrião é liberado da zona pelúcida. -/- • _____FERTILIZAÇÕES ATÍPICAS -/- Polispermia -/- É a penetração de dois ou mais espermatozoides no óvulo. Esta condição é letal nos mamíferos, já que o número cromossômico desse zigoto é maior que 2n, o envelheci-mento do ovócito da porca, como consequência do serviço tardio, favorece a apresentação da polispermia, por isso, é comum ver números de nascimentos de média de 10 a 12 leitões por parição nessa espécie. Nas aves, no entanto, a penetração de mais de um espermatozoide é normal, embora apenas um pronúcleo masculino se formará, fundindo-se com o feminino. -/- Figura 6: etapas do processo de segmentação/clivagem. Fonte: aula de reprodução da professora Domenica Palomaris, UFT. -/- Ginogênese -/- É o desenvolvimento de um embrião a partir de um óvulo normal fecundado por um espermatozoide, mas sem a fusão dos cromossomos masculinos com os da fêmea. A função do espermatozoide, nesse caso, é a de ativação do ovócito para que este inicie seu desenvolvimento, mas não há fusão com o núcleo do espermatozoide. Ocorre em plantas, em nematódeos e em algumas espécies de peixes, por exemplo a Poecilia formosa, espécie em que os ovócitos das fêmeas são ativados por machos de outra espécie relacio-nada. -/- Partenogênese -/- Consiste no desenvolvimento do embrião sem a participação do espermatozoide. Ocorre em alguns insetos, o zangão, por exemplo, é partenogenético. Também pode apresentar-se em perus, cujos embriões são machos e, geralmente, morrem antes da eclosão. -/- • _____GÊMEOS -/- Existem dois tipos de gêmeos: idênticos ou monozigóticos e os não idênticos ou dizigóticos. -/- Idênticos ou monozigóticos -/- Originam-se do mesmo zigoto, sendo assim, possuem o mesmo genótipo e um fenótipo similar e, portanto, são do mesmo sexo. Em laboratório é possível gerá-los ao seccionar uma mórula em duas ou mais partes, por meio de um micromanipulador. Uma vez que possuem o mesmo genótipo, os produtos resultantes são clones. -/- Não idênticos ou dizigóticos -/- Provêm da fertilização de dois óvulos distintos por espermatozoides diferentes. Possuem, portanto, genótipos e fenótipos diferentes, e podem ser de sexo diferente. -/- REFERÊNCIAS BIBLIOGRÁFICAS -/- ALBERTS, Bruce et al. Biologia molecular da célula. Artmed Editora, 2010. AUSTIN, Colin Russell; SHORT, Roger Valentine. Reproduction in Mammals, Book I: Germ Cells and Fertilization. 1982. BEARDEN, Henry Joe et al. Reproducción animal aplicada. México: Manual Moderno, 1982. BOSCH, P.; WRIGHT JR, R. W. The oviductal sperm reservoir in domestic mammals. Archivos de medicina veterinaria, v. 37, n. 2, p. 95-105, 2005. CAPALLEJAS, Roberto Brito; RODRÍGUEZ, Lourdes Tagle. Fisiología de la reproducción animal: con elementos de biotecnología. Editorial Félix Varela, 2010. CROXATTO, Horacio B. Physiology of gamete and embryo transport through the fallopian tube. Reproductive biomedicine online, v. 4, n. 2, p. 160-169, 2002. CUPPS, Perry T. (Ed.). Reproduction in domestic animals. Elsevier, 1991. DIEDRICH, Smidt et al. Endocrinología y Fisiología de la Reproducción de los Animales Zootécnicos. 1972. DUKES, Henry Hugh; SWENSON, Melvin J.; REECE, William O. Dukes fisiologia dos animais domésticos. Editora Guanabara Koogan, 1996. FERREIRA, A. de M. Reprodução da fêmea bovina: fisiologia aplicada e problemas mais comuns (causas e tratamentos). Juiz de Fora: Minas Gerais–Brasil, p. 422, 2010. HAFEZ, Elsayed Saad Eldin; HAFEZ, Bahaa. Reprodução animal. São Paulo: Manole, 2004. HUNTER, Ronald Henry Fraser. The Fallopian tubes in domestic mammals: how vital is their physiological activity?. Reproduction Nutrition Development, v. 45, n. 3, p. 281-290, 2005. HUNTER, R. H. F.; RODRIGUEZ‐MARTINEZ, H. Capacitation of mammalian spermatozoa in vivo, with a specific focus on events in the Fallopian tubes. Molecular Reproduction and Development: Incorporating Gamete Research, v. 67, n. 2, p. 243-250, 2004. GALINA, Carlos; VALENCIA, Javier. Reproducción de los animales domésticos. 2006. HOPPER, Richard M. (Ed.). Bovine reproduction. John Wiley & Sons, 2014. HYTTEL, Poul; SINOWATZ, Fred; VEJLSTED, Morten. Embriologia veterinária. Elsevier Brasil, 2012. KÖLLE, Sabine; REESE, Sven; KUMMER, Wolfgang. New aspects of gamete transport, fertilization, and embryonic development in the oviduct gained by means of live cell imaging. Theriogenology, v. 73, n. 6, p. 786-795, 2010. MCKINNON, Angus O. et al. (Ed.). Equine reproduction. John Wiley & Sons, 2011. OLIVERA, Martha et al. El espermatozoide, desde la eyaculación hasta la fertilización. Revista Colombiana de Ciencias Pecuarias, v. 19, n. 4, p. 426-436, 2006. PLANT, Tony M.; ZELEZNIK, Anthony J. (Ed.). Knobil and Neill's physiology of reproduction. New York: Academic Press, 2014. RODRIGUEZ-MARTINEZ, Heriberto. Role of the oviduct in sperm capacitation. Theriogenology, v. 68, p. S138-S146, 2007. SAAVEDRA LEOS, María Dolores. Estudio de la composición de los gránulos corticales y del oolema de ovocitos porcinos y bovinos madurados y fecundados in vitro. Proyecto de investigación:, 2010. SENGER, Phillip L. et al. Pathways to pregnancy and parturition. Current Conceptions, Inc, 2004. SUAREZ, Susan S. The oviductal sperm reservoir in mammals: mechanisms of formation. Biology of Reproduction, v. 58, n. 5, p. 1105-1107, 1998. VALENCIA MÉNDEZ, Javier de J. Fisiología de la reproducción porcina. 1986. -/- FIXAÇÃO DO ASSUNTO -/- 1. Defina e diferencie fertilização e segmentação. -/- 2. Disserte sobre o transporte do ovócito. Por que no istmo o transporte do ovócito se torna lento? -/- 3. Fale sobre a eficiência do transporte do gameta no trato genital da fêmea e sobre a retenção de ovócitos pela égua. -/- 4. Defina as células do cumulus e explique seu papel sobre o ovócito. -/- 5. Quais as estruturas que compõem o ovócito? Qual a função de cada uma? -/- 6. Todos os ovócitos das fêmeas domésticas são iguais? Justifique. -/- 7. Disserte sobre o papel dos hormônios e das secreções sobre o transporte do ovócito no trato genital da fêmea. -/- 8. Disserte sobre o transporte do espermatozoide. Por que há transporte rápido e lento dos espermatozoides? -/- 9. Fale sobre o local de deposição do sêmen nas espécies domésticas e como esse influen-cia na eficiência da reprodução. -/- 10. Por que a vida média do espermatozoide canino é maior que as outras espécies? -/- 11. Quais as mudanças que os espermatozoides precisam sofrer para conseguir êxito na fertilização e por quê? -/- 12. Defina fase de transporte rápido, fase sustentada e hipermotilidade. Qual a importân-cia de cada um? -/- 13. Como ocorre a reação acrossômica? -/- 14. O que é polispermia e como ocorre seu bloqueio? 15. Como ocorre a ativação do ovócito e como se formam os pronúcleos? -/- 16. O que é e qual a importância da singamia? -/- 17. Disserte sobre as divisões de segmentação e qual a importância destas para o êxito da reprodução. -/- 18. Defina e diferencia mórula e blastocisto. -/- 19. Defina e diferencie ginogênese e partenogênese. -/- 20. Qual o papel endócrino e quais hormônios e enzimas atuam sobre o transporte de gametas, sobre a fertilização e sobre a segmentação? (shrink)

Regarding the relation of Plato’s early and middle period dialogues, scholars have been divided to two opposing groups: unitarists and developmentalists. While developmentalists try to prove that there are some noticeable and even fundamental differences between Plato’s early and middle period dialogues, the unitarists assert that there is no essential difference in there. The main goal of this article is to suggest that some of Plato’s ontological as well as epistemological principles change, both radically and fundamentally, between the early and (...) middle period dialogues. Though this is a kind of strengthening the developmentalistic approach corresponding the relation of the early and middle period dialogues, based on the fact that what is to be proved here is a essential development in Plato’ ontology and his epistemology, by expanding the grounds of development to the ontological and epistemological principles, it hints to a more profound development. The fact that the bipolar and split knowledge and being of the early period dialogues give way to the tripartite and bound knowledge and benig of the middle period dialogues indicates the development of the notions of being and knowledge in Plato’s philosophy before the dialogues of the middle period. -/- Keywords Plato; early dialogues; middle dialogues; being; knowledge; development -/- Introduction The differences between two groups of the early and middle period dialogues have always been a matter of dispute. Whereas the developmentalists like Vlastos, Silverman (2002), Teloh (1981), Dancy (2004) and Rickless (2007) think that from the early to the middle dialogues Plato’s philosophy changes, at least in some essential points, the unitarists like Kahn, Cherniss and Shorey believe that there happens no development and the differences must be taken as natural, ignorable and even pedagogic. In his well-known article, Socrates contra Socrates in PLATO, Vlastos lists ten theses of difference between two groups of dialogues. The first group which includes Plato’s early dialogues he divides to 'elenctic' (Apology, Charmides, Crito, Euthyphro, Gorgias, Hippias Minor, Ion, Laches, Protagoras and Republic I) and 'transitional' (Euthydemus, Hippias Major, Lysis, Menexenus and Meno) dialogues. These transitional come after all the elenctic dialogues and before all the dialogues of the second group which compose Plato’s middle period dialogues, including (with Vlastos' chronological order) Cratylus, Phaedo, Symposium, Republic II-X, Phaedrus, Parmenides and Theaetetus (1991, 46-49). Vlastos asserts strictly that his list of differences are 'so diverse in content and method that they contrast as sharply with one another as with any third philosophy you care to mention, beginning with Aristotole’s' (ibid, 46). Vlastos’ list of differences between two Socrateses is considered a view breaking sharply between the early and the middle dialogues. Besides all ten differences between the two Socrateses in Vlastos’ list that can be supportive for our doctrine here, we intend to focus on some ontological as well as epistemological distinctions that have not completely been discussed hitherto. Contrary to the developmentalist theory of Vlastos, unitarian theory of Charles Kahn wishes to eliminate any substantial difference between the early and the middle dialogues. He distinguishes seven 'pre-middle' or 'threshold' dialogues including Laches, Charmides, Euthyphro, Protagoras, Meno, Lysis and Euthydemus from the other Socratic dialogues which he calls 'earliest group' (1996, 41). The threshold dialogues, Kahn thinks, 'embarke upon a sustained project' that is to reach to its climax in the middle period dialogues, namely Phaedo, Symposium and Republic. Believing in that there is no 'fundamental shift'between the early and middle dialogues (ibid, 40), Kahn thinks the Socratic dialogues are just the 'first stage' with a 'deliberate silence' towards the theories of later periods (ibid, 339). One of the reasons of the surprising fact that Plato gives no hint of the metaphysics and epistemology of the Forms in the early dialogues, he thinks, is the pedagogical advantages of aporia. He thinks that Plato 'obscurely', and mostly because of education, hinted to some doctrines and conceptions in his early dialogues and with the aim of clarifying them only in the later ones (ibid, 66). The seven threshold dialogues, Kahn asserts, 'had been designed from the first' to prepare the pupils and readers for the views expounded in the middle period dialogues (ibid, 59-60). To show that the differences of the two Socrateses of the early and middle period dialogue are in their onto-epistemological grounds and thence cannot be explained by a unitaristic view, we try to draw the ontological and epistemological principles of the early dialogues in the first part below in order to show, in the second part, that those principles have been developed in the middle period dialogues. -/- A. The Onto-Epistemologic Principles of the Early Dialogues Socratic dialogues are paradoxical about knowledge because while being knowledge-oriented always searching for knowledge, they deny it and even never discuss it directly. Three elements of Socrates’ way of searching Knowledge throughout the early dialogues, i.e. Socratic 'what is X?' question, his disavowal of knowledge and his elenctic method combined together produce something like a circle which works, more or less, in the same way in these dialogues. Though this circle is an embaressing inquiry always resulting in ignorance instead of knowledge, its motivation is surprisingly Socrates’ passionate enthusiasm for knowledge, an intensive love of wisdom. The starting point of this circle is Socrates’ confession of having no knowledge which might be explicitly asserted or presupposed, maybe because it was one of the famous characteristics of Socrates; a confession always paradoxically accompanied with his intense longing for knowledge (e.g., Gorgias 505e4-5). Every time Socrates encounters with someone who thinks he knows something (οἴεταί τι εἰδέναι) (Apology 21d5) and tries to examine him. This examination seems to be the simplest one asking just what it is that he knows. Socrates’ elenchus, therefore, is always connected with 'what is X?' (τίς ποτέ ἐστιν) question, a question that most of the early dialogues of Plato are concerned with; 'what is courage?' in the Laches, 'what is piety?' in Euthydemus, 'what is temperance?' in Charmides and 'what is beauty?' in Hippias Major. This question we call here 'Socratic question' and probably is the very question the historical Socrates used to employ, is tightly interrelated with both his disavowal and his elenchus. He disclaims knowledge because he cannot find the answer to the question himself and he rejects others’ since they cannot offer the correct answer too. Every interlocutor can claim he knows X, if and only if he can answer the Socratic question. Otherwise, he is more of an ignorant than of a knower of τί ποτέ ἐστι X. Knowing the answer to this question is, thus, knowledge’s criterion for Socrates. Having found out that he cannot answer what it is which he would claim to know, the interlocutor comes to the point Socrates was there at the beginning. The least advantage of this circle is that he becomes as wise as Socrates does about the subject, becoming aware that he does not know it. At the end of the circle they are both still at the beginning, not knowing what X is. So let us first take a glance at these three elements. Socratic disavowal of knowledge is strictly asserted in some passages. At Apology 21b4-5, Socrates says: -/- I do not know of myself being wise at all (οὔτε μέγα οὔτε σμικρὸν σύνοιδα ἐμαυτῷ σοφὸς ὤν) -/- Moreover, at 21d4-6: -/- None of us knows anything worthwhile (καλὸν κἀγαθὸν εἰδέναι) …. I do not know (οἶδα) neither do I think I know. -/- In Charmides Socrates speaks about a fear about his probable mistake of thinking that he knows (εἰδέναι) something when he does not (166d1-2). The somehow generalization of this disavowal can be seen in Gorgias. After calling his disavowal 'an account that is always the same' (509a4-5), Socrates continues (a5-7): -/- I say that I do not know (οἶδα) how these things are, but no one I have ever met, like now, who can say anything else without being absurd. -/- At the end of Hippias Major (304d7-8), Socrates affirms his disavowal of knowledge of 'what is X?' this time about the fine: -/- I do not know (οἶδα) what that is itself (αὐτὸ τοῦτο ὅτι ποτέ ἐστιν). Some other passages, however, made a number of scholars dubious about Socrates’ disavowal. Vlastos mentions Apology 29b6-7 as an evidence : 'that to do wrong and to disobey one’s master, both god and men, I know (οἶδα) to be evil and shameful'. He thinks that if we give this single text 'its full weight' it can suffice to show that Socrates does claim knowledge of a moral truth (1985, 7). Vlastos’ claim is not admittable since it would be too strange, I think, for a man like Socrates to violate his disavowal claim just after emphasizing it. We can see his claim just before the already mentioned passage: -/- And surely it is the most blameworthy ignorance to believe that one knows what one does not know. It is perhaps on this point and in this respect, gentlemen, that I differ from the majority of men and if I were to claim that I am wiser than anyone in anything it world be in this, that, as I have no adequate knowledge (οὐκ εἰδὼς ἱκανῶς) of things in the underworld, so I do not think I have (οὐκ εἰδέναι) (Apology 29b1-6) Vlastos tries to solve what he calls the 'paradox' of Socrates’ disavowal of knowledge distinguishing the 'certain' knowledge from 'elenctic' knowledge (1985, 11) and thinking that when Socrates avows knowledge, we must perceive it as an elenctic knowledge, a knowledge its content 'must be propositions he thinks elenctically justifiable' (ibid, 18). Irwin’s solution is the distinction of knowledge and belief. He approves that Socrates does not 'explicitly' make such a distinction, but still thinks that Socrates’ 'test for knowledge would make it reasonable for him to recognize true belief without knowledge, and his own claims are easily understood if they are claims to true belief alone' (1977, 40). While I agree with Vlastos up to a point, I strongly disagree with Irwin about the early dialogues. As I will try to show below, we are not permitted to consider any kind of distinction within knowledge in Socratic dialogues because only one category of knowledge is alluded to there and the distinction of knowledge and belief thoroughly belongs to the second Sorcates. Although no kind of distinction can be admittable here, I think Vlastos’ distinction can be accepted only if we regard it as a distinction between knowledge, which is unique and without any, even incomparable, rival, and a semi-idiomatic and ordinary one that is a necessary requirement for any argument, and thus, unavoidable even for someone who does not claim any kind of knowledge. An apparent evidence of this is Gorgias 505e6-506a4: -/- I go through the discussion as I think it is (ὡς ἄν μοι δοκῇ ἔχειν), if any of you do not agree with admissions I am making to myself, you must object and refute me. For I do not say what I say as I know (οὐδὲ γάρ τοι ἔγωγε εἰδὼς λέγω ἃ λέγω) but as searching jointly with you (ζητῶ κοινῇ μεθ᾽ ὑμῶν). -/- The minimal degree of knowledge everyone must have to take part in an argument, conduct it and use the phrase "I know" when it is necessary is what Socrates cannot deny. We can call it elenctic knowledge only if we agree that it is not the kind of knowledge that Socrates has always been searching, the one that can be accepted as the answer of Socratic 'what is X?' question. His disavowal of knowledge is applied only to the knowledge which can truly be the answer of Socratic question and pass the elenctic exam; a knowledge that, I believe, is never claimed by first Socrates. Socrates conducts his method of examining his interlocutors’ knowledge, our second element here, by almost the same method repeated in Socratic dialogues. That whether we are allowed to regard all the examinations of Socrates in the early dialogues as based on the same or not has been a matter of dispute. Vlastos himself (1994, 31) distinguished Euthydemas, Lysis, Menexenns and Hippias Major from the other Socratic dialogues because he thinks Socrates has lost his faith to elenchus in there. Irwin (1977, 38) distinguishes Apology and Crito where Socrates’ own convictions is present. Contrary to some scholars like Benson (2002, 107) who take elenchus in all the Socratic dialogues as a unique method, Michelle Carpenter and Ronald M. Polansky (2002, 89-100) argue pro the variety of methods of elenchus. Thomas C. Brickhouse and Nicholas D. Smith (2002, 145-160) even reject such a thing as Socratic elenchus which can gather all of the Socrates’ various arguments under such a heading. There can be no solution for the problem of elenchus, they think, is due to 'the simple reason that there is no such thing as 'the Socratic elenchos"'(p.147). Though we consider elenchus a somehow determined process and a part of Socratic circle in the early dialogues, all we assume is that whatever differences it might have in different dialogues, it has the same onto-epistemological principles and, thus, we are not going to take it necessarily as a unique method. This method sets out to prove that the interlocutors are as ignorant as Socrates himself is. That whether elenchus is constructive, capable of establishing doctrines as Vlastos (1994) or Brickhouse and Smith (1994, 20-21) believe or not is another issue to which this paper is not to claim anything. What is crucial for our discussion here is that elenchus does not reach to the very knowledge Socrates is looking for. This is strictly against Irwin who thinks that not only elenchus leads to positive results, 'it should even yield knowledge to match Socrates’ conditions'(1977, 68, cf. 48). He does not explain where and how they really yield to that kind of knowledge. He explains his elenctic method in his apology in the court (Apology 21-22), that how he used to examine wise men, politicians, poets and all those who had the highest reputation for their knowledge and every time found that they have no knowledge. If we accept, as I strongly do, that Socrates’ disavowal of his knowledge is not irony, it might seem more reasonable to agree that the process that has that disavowal as its first step cannot be irony as well. The key of the circle which can explain why Socrates disclaims knowledge and how he can reject others’ claim of having any kind of knowledge lies in the third element, Socratic question. In Hippias Major (287c1-2), Socrates asks: 'Is it not by Justice that just people are Just? (ἆρ᾽ οὐ δικαιοσύνῃ δίκαιοί εἰσιν οἱ δίκαιοι). He insists at 294b1 that they were searching for that by which (ᾧ) all beautiful things are beautiful (cf. b4-5, 8). At Euthyphro 6d10-11 it is said that the Socratic question is waiting for 'the form itself (αὐτὸ τὸ εἶδος) by which (ᾧ) all the pious actions are pious; and at 6d11-e1: -/- Through one form (που μιᾷ ἰδέᾳ) impious actions are impious and pious actions pious. -/- Since the X itself is that by which X is X, knowing 'X itself' is the only way of knowing X. It is probably because of this that Socrates makes the distinction between the ousia as a right answer to the question and effect as a wrong one: -/- I am afraid, Euthyphro, that when you were asked what piety is (τὸ ὅσιον ὅτι ποτ᾽ ἐστίν) you did not wish to make clear its nature itself (οὐσίαν … αὐτοῦ) to me, but you said some effect (πάθος) about it. (Euthp. 11a6-9) -/- 1. Knowledge of what X is Now it is time to look for the onto-epistemological principles of Socratic circle and its three elements. It cannot reasonably be expected from the first Socrates to present us explicitly and clearly formulated principles of his onto-epistemology when such explications cannot be found even in the second Socrates who has some obviously positive theoris. Since there must be some principles underlying this first systematic inqury of knowledge, we must seek to them and be satisfied with elicitation of the first Socratas’ principle. What will be drawn out as his principles cannot and must not, thus, be taken as very fix and dogmatic principles. Some very slightest principles and grounds suffice for our purposes here. The first principle that is the prima facie significance of the Socratic question and his implementation of all those elenctic arguments I call the principle of 'Knowledge of What X is' (KWX): -/- KWX To know X, it is required to know what X is. -/- Aristotle (Metaphysics 1078b23-25, 27-29, 987b4-8) takes Plato’s τί ἐστι question as seeking the definition of a thing that is the same as historical Socrates’ search but applying to a different field. That Plato’s 'what is X?' question was a search for definition became the prevailed understanding of this question up to now. I am going neither to discuss the answer of Socratic question nor to challenge taking it as definition. What I am to insist is that knowledge is attached firmly to the answer of the question: Knowledge of X is not anything but the knowledge of what X is. It entails, certainly, the priority of this knowledge to any other kind of knowledge about X but it also has something more fundamental about the relation of knowledge and Socratic question. Socrates’ exclusive focus on the answer of his question can authorize the consideration of such an essential role for KWX in his epistemolgoy. The total rejection of his interlocutors’ knowledge when they are unable to answer the question can be regarded as a strong evidence for it. Socrates’ elenctic method and his rejection of others’ knowledge in the early dialogues, which all end aporetically with no one accepted as knower and nothing as knowledge, prevent us from finding any positive evidence for this. We have to be content, therefore, of negative evidences which, I think, can be found wherever Socrates rejects his interlocutors’ knowledge when they are not able to give an acceptable answer to his 'what is X?' question. 2. Bipolar Epistemology Socrates’ rejection of his interlocutors’ knowledge has another epistemological principle as its basis. Let me call this principle Bipolar Epistemology' (BE): BE There is no third way besides knowledge and Ignorance. -/- BE says that about every object of knowledge there are only two subjective statuses: knowledge and Ignorance. Socrates’ disavowal, however, says nothing but that he is ignorant of knowledge of X because he does not know what X is. This means that BE is presupposed here. Socrates’ elenchus and his rejection of interlocutors’ having any kind of knowledge are the necessary results of the fact that he does not let any third way besides knowledge and ignorance. The first Socrates never let anyone partly know X or have a true opinion about it, as he would not let anyone know anything about X when he did not know what X is. -/- 3. Bipolar Ontology The principle of BE in first Socrates’ epistemology is parallel to another principle in his ontology. Plato’s bipolar distinction between being and not being is as strict and perfect as his distinction between knowledge and ignorance. This principle I shall call the principle of 'Bipolar Ontology' (BO): BO Being is and not being is not. BO is apparently the same with the well-known Parmenidean Principle of being and not being (cf. Diels-Kranz (DK) Fr. 2.2-5). Euthydemus’ statement against the possibility of false knowledge can be good evidence for this principle: -/- The things which are not surely do not exist (τὰ δὲ μὴ ὄντα … ἄλλο τι ἢ οὐκ ἔστιν). (Euthydemus 284b3-4) -/- He continues (b4-5): -/- There is nowhere for not being to be there (οὖν οὐδαμοῦ τά γε μὴ ὄντα ὄντα ἐστίν). -/- That BE does not let true opinion as a third option besides knowledge and ignorance seems to be related to BO’s rejecting a third option besides being and not being, which is itself the basis of the impossibility of false belief. Socrates’ elaborate discussion of the problem of false belief in Theatetus that leads to a more decisive discussion and finally to some solutions in Sophist can make our consideration of BO for the first group of dialogues authentive. -/- 4. &5. Split Knowledge and Split Being The fourth principle I shall call the principle of 'Split Knowledge' (SK): -/- SK Knowledge of X is separated from any other knowledge (of anything else) as if the whole knowledge is split to various parts. -/- This Principle is hinted and criticized as Socrates’ way of treating with knowledge in Hippias Major: -/- But Socrates, you do not contemplate the entireties of things, nor do people you have used to talk with (τὰ μὲν ὅλα τῶν πραγμάτων οὐ σκοπεῖς, οὐδ᾽ ἐκεῖνοι οἷς σὺ εἴωθας διαλέγεσθαι). (301b2-4) -/- Contrary to Rankin who regards the passage as 'antilogical, almost eristic in tone rather than presenting a serious philosophy of being' (1983, 54), I think it can be taken as serious. Hippias criticizes Sorcates that he does not contemplate (σκοπεῖς) the entireties of things (ὅλα τῶν πραγμάτων), a critique which Socrates is not its only subject but all those whom Socrates accustomed to talk with (ἐκεῖνοι οἷς σὺ εἴωθας διαλέγεσθαι). This last phrase, I think, extends this critic beyond this dialogue to other Socratic dialogues. Hippias’ use of the perfect tense of the verb ἔθω (to be accustomed) is a good evidence of this extension. We can get, thus, these ἐκεῖνοι as Socrates’ interlocutors in his other dialogues that hints that this criticism has the epistemological groundings of the previous dialogues as its subject. What ἐκεῖνοι οἷς σὺ εἴωθας διαλέγεσθαι points to is that Hippias does not have in mind Socrates’ way of treating things only in this dialogue, but he is also criticizing Socrates’ way throughout his dialogues. At 301b4-5, Socrates and his interlocutors’ way of beholding things is described as such: -/- You people knock (κρούετε) at the fine and each of the beings (ἕκαστον τῶν ὄντων) by taking each being cut up in pieces (κατατέμνοντες) in words (ἐν τοῖς λόγοις). This leads us to our next principle that is parallel to, and the ontological side of, SK, the principle of 'Split Being'(SB): -/- SB Everything (being) is separated from any other thing as if the whole being is split to many beings. -/- Socrates and his interlocutors and thus, as we saw, the Socratic dialogues are accused to regard everything as it is separated from all other things. This separation is en tois logois that, I think, can reasonably be taken as saying that Socratic dialogues (it refers of course to the dialogues before Hippias Major) cut up all things which have the same name/definition from all other things and try to understand them separately, without considering other things that are not in their logos. They, for example in Hippias Major, are cutting up to kalon and try to understand what it and all others inside this logos are by separating it from all other things. This is directed straightly against Socratic question and the way Socratic dialogues follow to find its answer, every time separating one logos. As Meyer (1995, 85) points out, every question 'presupposes that the X in question in a logos is something' and 'every answer to every question aims at unity' (84). The critique of Hippias Major is, therefore, at the same time a critique of SK and SB. It is also a critique of KWX because it is only based on KWX that Socratic dialogues could search for the answer of 'what is X' question supposing that knowing what X is is enough for the knowledge of X. SK and KWX are absolutely interdependent. What Socrates and all his previous interlocutors have neglected in Socratic dialogues, Hippias says, was 'continuous bodies of being' (διανεκῆ σώματα τῆς οὐσίας) (301b6). Either this theory actually belongs to the historical Hippias as it is being said or not, it is strictly criticizing SB. We have the same phrase with changing sūma to logos some lines later at 301e3-4: διανεκεῖ λόγῳ τῆς οὐσίας. Although this theory that can be observed as both an ontological and an epistemological theory is rejected by Socrates (301cff.), it is still against first Socrates’ onto-epistemological principles and might let us look at what is rejected as Socratic prineple. -/- 6. Knowledge is of Being The sixth principle that I think is presupposed by the first Socrates, is the 'Knowledge of Being' Principle (KB): -/- KB Knowledge is of Being. -/- This principle is obviously the source of the problem of false knowledge, a very important problem throughout Plato’s philosophy. We face this problem maybe for the first time in Euthydemus. In less than 20 Stephanus’ pages, 276-295, we are encountered with different interwoven problems about knowledge , all grounded in the problem of false opinion. Having challenged the obvious possibility of telling lies at 283e, at 284 Euthydemus discusses it saying that the man who speaks is speaking about 'one of those things that are (ἓν μὴν κἀκεῖνό γ᾽ ἐστὶν τῶν ὄντων)' (284a3) and thus speaks what is (λέγων τὸ ὄν) (a5). He must necessarily be saying truth when he is speaking what is because he who speaks what is (τὸ ὄν) and the things that are (τὰ ὄντα) speaks truth (τἀληθῆ λέγει) (a5-6). This is based on Parmenidean principle of the impossibility of being of not being which Euthydemus restates (284b3-4) and we mentioned discussing BO principle above. The things that are not are nowhere (οὐδαμοῦ) and there is no possibility for anyone to do (πράξειεν) anything with them because they must be made as being before anything else can be done, which is impossible (b5-7). The words, then, are of things that exist (εἰσὶν ἑκάστῳ τῶν ὄντων λόγοι) (285e9) and as they are (ὡς ἔστιν) (e10). The result is that no one can speak of things as they are not. It is this impossibility of false speach that is extended to thinking (δοξάζειν) at 286d1 and leads to the impossibility of false opinion (ψευδής … δόξα) (286d4). The general conclusion is asserted at 287a extending this impossibility to actions and making any kind of mistake. Not only knowledge is of being but speech, thought and action are of being simply because of the fact that nothing can be of not being. -/- B. First Socrates’ Principles in the Middle Period Dialogues Out of what were presupposed or criticized mostly in five dialogues, Euthyphro, Euthydemus, Hippias Major, Laches and Charmides, we tried to draw the first Socrates’ principles. Our inquiry here is directed to find out the fate of these principles in the three dialogues of the middle period, Meno, Phaedo and Republic. To do this, first we ought to check the situation of Socratic circle in these dialogues. The Socratic circle that was predominant in the early dialogues, does not look like a circle here anymore though they certainly have some features in common. Meno, Phaedo and Republic II-X are not committed to the principles of the circle and the whole circle in disrupted in them. The difference of the two Socrateses towards acquiring knowledge is obvious. The Socrates of Meno, Phaedo and Republic is evidently more self-confident that he can get to some truths during his arguments as he does. They are in their first appearance, as almost all other dialogues, committed to Socrates’ disavowal. All of them try to keep the shape of the Socratikoi Logoi genre, which is committed to the historical Socrates’ way of discussion; a dramatic personage who is to challenge his interlocutors, ask them and refuse the answers. Nevertheless, the fact is that what we have in common between two groups of dialogues is mostly a dramatic structure. Whereas the first group’s arguments are based on Socrates’ disavowal and lead to no positive results, the second group is decisively going to achieve some positive results. The aim of the first Socrates was to show others that they are ignorant of what they thought they knew. The new Socrates of Meno, on the opposite, makes so much efforts to show that the slave boy has within himself true opinions (ἀληθεῖς δόξαι) about the things that he does not know (οἶδε) (85c6-7). Despite his lack of knowledge, he has true opinions nevertheless. The way from these true opinions to knowledge, as Socrates states, is not so long. These true opinions are now like a dream but 'can become knowledge of the same things not less accurate than anyone’s' (οὐδενὸς ἧττον ἀκριβῶς ἐπιστήσεται περὶ τούτων) (c11-d1), if they be repeated by asking the same questions. The most outstanding text regarding Socrates’ disavowal is Meno 98b where he explicitly claims knowledge: -/- And indeed I also speak as (ὡς) one who does not know (εἰδὼς) but is guessing (εἰκάζων). However, [about the fact] that true opinion and knowledge are different, I do not altogether expect (δοκῶ) myself to be guessing (εἰκάζειν), but if I say about anything that I know (εἰδέναι) -which about few things I say- this is one of the things that I know (οἶδα). (98b1-5) This passage is very significant about Plato’s disavowal of knowledge. There can hardly be found, I think, anywhere else in Plato’s corpus where Socrates speaks about his knowledge of something as such. He says first that he speaks as someone who does not know. This ὡς οὐκ εἰδὼς λέγω comparing with what he used to say in the first group, οὐκ οἶδα, has this added ὡς. Socrates does not claim strongly anymore that he does not know anything but speaks only as someone who does not know. He needs this ὡς not only because he is going to accept that he does know some, though few, things immediately after this sentence, but also because he needs his previous disavowal to be loosened from Meno on. He does not merely say here that he knows something. It is then different from the examples mentioned before which could be taken as idiomatic or at least not emphatic. Socrates’ remarkable emphasis on distinguishing εἰδέναι from εἰκάζειν departs it from all other passages where he says only he knows something. Moreover, he claims definitely that he has knowledge about few (ὀλίγα) things. From the early to the middle dialogues, Socrates’ attitude to knowledge has totally renewed its face. He brings forth a new concept, true opinion, and he does not speak of knowledge as he used to before; the rough, perfect and unachievable knowledge of the first group has turned to something more smooth, realistic and achievable. Comparing with the early dialogues that did not set out from the first to reach positive results, the middle ones are extraordinarily and surprisingly positive and hence destroy the basis of the Socratic circle. The questions and answers are purposely directed to some specific new theories; most of them are not directly related to the topics or the main questions of the dialogues. They are suggested when Socrates draws the attention of the interlocutor away from the main question because of the necessity of another discussion. Even if the main question remains unanswered, we have still many positive theories, prominently of metaphysical type. These theories are so abundant and dominant in these dialogues, especially Phaedo and Republic, that one might think that they may appear to be arbitrarily sandwiched in there. This helps dialogues to keep their original Socratic structure while they are suggesting new theories. Hence, the Socratic question of 'what is X?', though is still used to launch the discussion, is loosened and is forgotten for most part of the dialogues. Meno that has first a differently formulated question, 'can virtue be taught?', leads finally to the Socratic question of 'What is virtue?'. Phaedo is dedicated to the demonstration of the immortality of soul and the life after death without having a central Socratic question. The case of Republic is more complicated. The first book, on the one hand, has all the criteria of a Socratic circle: its 'what is justice?' question, Socrates’ strong disavowal (e.g. 337d-e), his rejection of all answers and coming back to the first point without finding out any answer. This Book, considered alone, is a perfect Socratic dialogue, as many scholars regard it as early and separated from other books. The books II-X are, on the other hand, far from implementing a Socratic circle. They have still the 'what is justice?' question as their incentive leading question, but they are, in most of the positive doctrines and methods that encompass the main parts, ignoring the question. Even these books that, I believe, are the farthest discussions from the Socratic circle are so cautious not to break the Socratic structure of the dialogue as long as it is possible. What is changed is not the structure of the dialogue but the ontological and epistemological grounds based on which new theories are suggested. -/- 1. Knowledge of the Good We can clearly see in the second group of dialogues that the KWX principle loses the place it had before in our first group. It is not, of course, rejected, but still we cannot say that it has the same situation. KWX that was based on Socratic question, as we discussed before, was the leading principle of the first Socrates’ epistemology and of the highest position. Other epistemological principles, SK directly and BE indirectly, were relying on Socratic question and therefore on KWX. Such a position does not belong to KWX from Meno on. What makes it different in the second Socrates is another principle that is needed it not only as its complementary principle but also as what is more fundamental. Plato, then, does not reject KWX in this period, but, it seems, he transcends to another more basic principle; a principle we shall call the principle of 'Knowledge of the Good' (KG): -/- KG Knowledge of X requires knowledge of the Good. -/- Whereas all the dialogues of our first group are free from any discuscon about KG, it bears a very important role in the second group so as becomes the superior principle of knowledge in Republic. Trying to solve the problem of teachability of virtue, Socrates says that it can be teachable only if it is a kind of knowledge because nothing can be taught to human beings but knowledge (ἐπιστήμην) (Meno 87c2). The dilemma will be, then, whether virtue is knowledge or not (c11-12) and since virtue is good, we can change the question to: whether is there anything good separate from knowledge (εἰ μέν τί ἐστιν ἀγαθὸν καὶ ἄλλο χωριζόμενον ἐπιστήμης) (d4-5). Therefore, the conclusion will be that if there is nothing good which knowledge does not encompass, virtue can be nothing but knowledge (d6-8). What let us discuss KG as an epistemological principle for the second Secrates is the relation he tries to establish between knowledge and the Good which, though is alongside with the mentioned thesis and the idea of virtue as knowledge, goes much deeper inside epistemology asking to regard the Good as the basis of knowledge. The effort of Phaedo cannot succeed in establishing the Good as the criterion of explanation and knowledge since, I think, it needs a far more complicated ontology of Republic where Socrates can finally announce KG. What is said in Republic is totally compatible with Phaedo 99d–e and the metaphor of watching an eclipse of the sun. In spite of the fact that we do not have adequate knowledge of the Idea of the Good, it is necessary for every kind of knowledge: 'If we do not know it, even if we know all other things, it is of no benefit to us without it' (505a6-7). The problem of our not having sufficient knowledge of the Idea of Good is tried to be solved by the same method of Phaedo 99d-e, that is to say, by looking at what is like instead of looking at thing itself (506d8-e4). It is this solution that leads to the comparison of the Good with sun in the allegory of Sun (508b12-13). What the Good is in the intelligible realm corresponds to what the sun is in the visible realm; as sun is not sight, but is its cause and is seen by it (b9-10), the Good is so regarding knowledge. It has, then, the same role for knowledge that the sun has for sight. Socrates draws our attention to the function of sun in our seeing. The eyes can see everything only in the light of the day being unable to see the same things in the gloom of night (508c4-6). Without the sun, our eyes are dimmed and blind as if they do not have clear vision any longer (c6-7). That the Good must have the same role about knowledge based on the analogy means that it must be considered as a required condition of any kind of knowledge: -/- The soul, then, thinks (νόει) in the same way: whenever it focuses on what is shined upon by truth and being, understands (ἐνόησέν), knows (ἔγνω) and apparently possesses understanding (νοῦν ἔχειν). (508d4-6) -/- Socrates does not use agathon in this paragraph and substitutes it with both aletheia and to on. He links them with the Idea of the Good when he is to assert the conclusion of the analogy: -/- That which gives truth to the objects of knowledge and the power of knowing to the knower, you must say, is the Idea of the Good: being the cause of knowledge and truth (αἰτίαν δ᾽ ἐπιστήμης οὖσαν καὶ ἀληθείας) so far as it is known (ὡς γιγνωσκομένης μὲν διανοοῦ). (508e1-4) Knowledge and truth are called goodlike (ἀγαθοειδῆ) since they are not the same as the Good but more honoured (508e6-509a5). KG, which had been implicitly contemplated and searched in Phaedo, is now explicitly being asserted in Republic. As what was quoted clearly proves, this principle is the very one which we can observe as the most fundamental principle of the second Socrates in Republic, corresponding to the role KWX had in the first Socrates. The Form of the Good in Republic, of which Santas speaks as 'the centerpiece of the canonical Platonism of the middle dialogues, the centerpiece of Plato’s metaphysics, epistemology, ethics and …' (1983, 256) much more can be said. Plato’s Cave allegory in Book VIII dedicates a similar role to the Idea of the Good. The Idea of the Good is there as the last thing to be seen in the knowable realm, something so important that its seeing equals to understanding the fact that it is the cause of all that is correct and beautiful (517b). Producing both light and its source in visible realm, it controls and provides truth and understanding in the intelligible realm (517c). -/- 2. Tripartite Epistemology BE is thoroughy rejected in the second Socrates and substituted by its opposite, the principle of 'Tripartite Epistemolgy' (TE): -/- TE Opinion is an epistemological status between knowledge and ignorance. BE of the first Socrates was denying any third way besides knowledge and ignorance which was the foundation of Socratic circle without which Socrates could not reject his interlocutors’ possessing any kind of knowledge. We cannot say, however, that the first Socrates had a third epistemological status in mind but rejected it. Such a status was unacceptable for him so that one can say that he would reject any kind of such status if suggested. There were only two possibilities about knowledge: either one knows something or he does not know it. TE, thus, was not the first Socrates’ discovery and, I think it is not the second Socrates’discovery. All we can see in our second group of dialouges is that he uses this principle as an already demonstrated one. Having examined the slave boy in Meno for the prupose of showing the working of recollection, it truns out that he has some opinions in him while he still does not know. Without trying to prove it, Socrates takes this as the distinction between knowledge and opinion: -/- So, he who does not know (οὐκ εἰδότι) about what he does not know (περὶ ὧν ἂν μὴ εἰδῇ) has within himself true opinions (ἀληθεῖς δόξαι) about the same things he did not know (περὶ τούτων ὧν οὐκ οἶδε) (85c6-7). -/- The same distinction is set between ὀρθὴν δόξαν and ἐπιστήμην at 97b5-6 ff. (also cf. 97b1-2: ὀρθῶς μὲν δοξάζων … ἐπιστάμενος). He connects then their difference to the myth of Daedalus, the statue that would run away and escape. So are true opinions, not willing to remain long in mind and thus not worthy until one ties them down by αἰτίας λογισμῷ (98a3-4). Socrates says that this tying down is anamnesis. We face, in Phaedo, the same relation is settled between knowledge as the process of being tied down and getting the capability to give an account, on the one hand, and anamnesis, on the other hand. When a man knows, he must be able to give an account of what he knows (Phaedo 76b5-6) and since not all people are able to give such an account, those who recollect, recollect what once they learned (76c4). Although the distinction between knowledge and opinion is not explicitly used in Phaedo, referring to the parallel link between knowledge plus account and anamnesis in Phaedo and Meno, one can say that those who cannot recollect are not able to give account and, thus, are in a state of opinion. What is said at Phaedo 84a, though not yet a definite distinction between knowledge and opinion, makes a distinction between their objects so as we can agree that it is presupposed. The soul of the philosopher, Socrates says, follows reason, stays with it forever and contemplates the divine, which is not the object of opinoin (ἀδόξαστον) (84a8, cf. Meno 98b2-5). The distinction of knowledge and belief in Republic has a significant difference with what we discussed in Meno and Phaedo since the distinction of Meno was based on anamnesis and thus more an epistemological distinction. Even in Phaedo that we do not have any elaborate discussion about the distinction, the only hint to the matter at 76 is bound to the theory of anamnesis. In addition to the relation of the distinction with this theory, there is another evidence that does not permit us to consider the distinction as an ontological distinction. Let’s see Meno 85c6-7: -/- So, he who does not know about what he does not know has within himself true opinions about the same things he did not know (τῷ οὐκ εἰδότι ἄρα περὶ ὧν ἂν μὴ εἰδῇ ἔνεισιν ἀληθεῖς δόξαι περὶ τούτων ὧν οὐκ οἶδε). (85c6-7) -/- This last sentence persists that the objects of knowledge and true opinion are the same. What Socrates is to say here is that whereas he does not know X he has true opinion about the same X. I think Socrates’ sentence that the slave boy οὐκ εἰδότι ἄρα περὶ ὧν ἂν μὴ εἰδῇ and his restatement of it by saying περὶ τούτων ὧν οὐκ οἶδε is because he wants to emphasize that the slave boy who does not know, has true opinion about the same thing. Socrates could say this just with using τούτων and there would be no necessity to bring περὶ ὧν ἂν μὴ εἰδῇ for οὐκ εἰδότι if he did not want to emphasize. -/- 3. Tripartite Ontology The distinction between knowledge and true opinion in Republic, on other side, has nothing to do with recollection, but is based on an ontological principle, 'Tripartite Ontology' (TO): -/- TO There are things that both are and are not. -/- This principle I confine, among our three dialogues of the second group, to Republic not extended to Meno and Phaedo, is obviously the opposite of BO. Speaking about the lovers of sights and sounds in the fifth book, Socrates distinguishes them from philosophers because their thought is unable to understand the nature of beautiful itself besides beautiful things (476a6-8) and hence they can only have opinions. The philosopher who, on the contrary, believes in beautiful itself and can distinguish it from beautiful things (476c9-d3), has knowledge because he knows, contrasting others who have opinion because they only opine (d5-6). Since those whose knowledge were degraded as opinion will complain about Socrates’ such calling their thought, he provides them the following argument (476e7-477b1): -/- - Does the person who knows, knows (γιγνώσκει) something (τὶ) or nothing (οὐδέν)? - He knows something (τί). - Something that is (ὂν) or is not (οὐκ ὄν)? - Something that is (ὂν) for how could something that is not be known (πῶς γὰρ ἂν μὴ ὄν γέ τι γνωσθείη)? - Then we have an adequate grasp of this: No matter how many ways we examine it, what completely is (παντελῶς ὂν) is completely knowable (παντελῶς γνωστόν) and what is in no way (μὴ ὂν δὲ μηδαμῇ) is in every way unknowable (πάντῃ ἄγνωστον). - A most adequate one. - Good. Now, if anything is such as to be and also not to be (ὡς εἶναί τε καὶ μὴ εἶναι), won’t it be intermediate (μεταξὺ) between what purely is (εἰλικρινῶς ὄντος) and what in no way is (μηδαμῇ ὄντος)? - Yes, it’s intermediate. - Then as knowledge (γνῶσις) is set over what is (τῷ ὄντι), while ignorance (ἀγνωσία) is of necessity set over what is not (μὴ ὄντι) mustn’t we find an intermediate between ignorance (ἀγνοίας) and knowledge (ἐπιστήμης) to be set over the intermediate, if there is such a thing? -/- From the third status of being we must reach to the third status of knowledge. The simple reading of this text can be an existential reading, taking the "is" of the mentioned sentences as existence. The problem is that when it is said that there is something that both is and is not reading "is" existentially, it sounds too bizarre to be acceptable. It cannot easily be understandable to have something as both existent and non-existent at the same time. This problem arose so many debates and led many scholars to reject the existential reading of "is" and suggest some other readings like predicative or veridical readings. I think though Plato’s complicated ontology of Republic cannot be correctly understood by a simple existential reading, this "is" cannot be free from existential sense of being and, thus, cannot be reduced to just a predicative or veridical sense of being. -/- 4. Bound Knowledges In addition to KG, the Good is also the basis of another principle in the second Socrates, namely the principle of 'Bound Knowledge' (BK): -/- BK Knowledge of everything is bound to the knowledge of the Good. -/- We distinguished BK from KG because we want to insist, in BK, on what had not been insisted upon in KG, that is, the binding role that the Good plays in the second Socrates, contrasting the absence of such a role in the first Socrates. Socrates remembers, in Phaedo, his wonderful keen on natural philosophers' wisdom when he was young. The origin of this enthusiasm was Socrates’ hope to know the cause of everything as they used to claim. When he was searching the matters of his interest on their basis, Socrates says, he became convinced he can get no acceptable answer from them and found himself blind even to the things he thought he knew before. One day he hears Anaxagoras’ theory that 'it is Mind that arranges and is the cause of everything (ὡς ἄρα νοῦς ἐστιν ὁ διακοσμῶν τε καὶ πάντων αἴτιος)' (Phd. 97c1-2 cf. DK, Fr.15.8-9, 11-12, 12-14) and thinks that he can finally find what he has always expected, i.e. something which can explain all things. What I intend to show here is that what makes Socrates hopeful is that Anaxagoras’ theory tries 1) to explain all things by one thing and 2) this explanation is understood by Socrates as if it is based on the concept of the Good. That Socrates was searching for one explanation for all things can be proved even from what he has been expecting from natural philosophers. The case is, nonetheless, more clearly asserted when he speaks about Anaxagoras’ theory. In addition to διακοσμῶν τε καὶ πάντων αἴτιος of 97c2 mentioned above, we have τὸ τὸν νοῦν εἶναι πάντων αἴτιον (c3-4) and τόν γε νοῦν κοσμοῦντα πάντα κοσμεῖν (c4-5) all emphasizing on the cause of all things (πάντα) which can clearly prove that one of the reasons which caused Socrates to embrace it delightfully was its claim to provide the cause of all things by one thing. Another reason was that Anaxagoras’ Mind, at least in Socrates’ view, was attempting to explain everything by the concept of the Good. This connection between Mind and Good belongs more to the essential relation they have in Socrates’ thinking than Anaxagoras’ theory because there are almost nothing about such a relation in Anaxagoras. The reason for Socrates’ reading can be that Mind is substantially compatible with Socrates’ idea of the relation between good and knowledge. Both the thesis 'no one does wrong willingly' and the theory of virtue as knowledge we pointed to above are evidences of this essential relation. Nobody who knows that something is bad can choose or do it as bad. The reason, when it is reason, that means when it is as it should be, when it is wise or when it knows, works only based on good-choosing. In this context, when Socrates hears that Mind is considered as the cause of everything, it sounds to him like this: good should be regarded as the basis of the explanation of all things. We see him, thus, passing from the former to the latter without any proof. This is done in the second sentence after introducing Mind: -/- I thought that if this were so, the arranging Mind would arrange all things and put each thing in the way that was Best (ὅπῃ ἂν βέλτιστα ἔχῃ). If one then wished to find the cause of each thing by which it either perishes or exists, one needs to find what is the best way (βέλτιστον αὐτῷ ἐστιν) for it to be, or to be acted upon, or to act. On these premises then it befitted a man to investigate only, about this and other things, what is the most excellent (ἄριστον) and best (βέλτιστον). The same man must inevitably also know what is worse (χεῖρον), for that is part of the same knowledge. (97c4-d5) This passage is a good evidence of Socrates’ leap from Anaxagoras’ Mind to his own concept of the Good that can explain why Socrates found Anaxagoras theory after his own heart (97d7). Mind is welcomed because of its capability for explanation on the basis of good to 'explain why it is so of necessity, saying which is better (ἄμεινον), and that it was better (ἄμεινον) to be so' (97e1-3). What Socrates thought he had found in Anaxagoras can indicate what he had been expecting from natural scientists before. Socrates could not be satisfied with their explanations because they were unable to explain how it is the best for everything to be as it is. It can probably be said, then, that it was the lack of the unifying Good in their explanation that had disappointed him. We must insist that we are discussing what Socrates thought that Anaxagoras’ theory of Mind should have been, not about Anaxagoras’ actual way of using Mind. Phaedo 97c-98b, is not about what Socrates found in Anaxagoras but what he thought he could find in it. On the contrary, it should also be noted that it was not this that was dashed at 98b, but Anaxagoras’ actual way of using Mind. It was Anaxagoras’ fault not to find out how to use such an excellent thesis (98b8-c2, cf. 98e-99b). Socrates gives an example to show how not believing in 'good' as the basis of explanation makes people be wanderers between different unreal explanations of a thing. His words δέον συνδεῖν (binding that binds together) as a description for the Good we chose as the name of BK principle: They do not believe that the truly good and binding binds and holds them together (ὡς ἀληθῶς τὸ ἀγαθὸν καὶ δέον συνδεῖν καὶ συνέχειν οὐδὲν οἴονται). (99c5-6) -/- Having in mind Plato’s well-known analogy of the sun and the Good at Republic 508-509, we can dare to say that his warning of the danger of seeing the truth directly like one watching an eclipse of the sun in Phaedo (99d-e) is more about the difficulty of so-called good-based explanation than its insufficiency, a difficulty which is precisely confirmed in Republic (504e-505a, 506d-e). Moreover, BK is asserted in a more explicit way in the Republic, where the Good is considered not only as a condition for the knowledge of X, as was noted above discussing KG, but also as what binds all the objects of knowledge and also the soul in its knowing them. At Republic VI, 508e1-3, when Socrates says that the Form of the Good 'gives truth to the things known and the power to know to the knower (τοῦτο τοίνυν τὸ τὴν ἀλήθειαν παρέχον τοῖς γιγνωσκομένοις καὶ τῷ γιγνώσκοντι τὴν δύναμιν ἀποδιδὸν)', he wants to set the Good at the highest point of his epistemological structure by which all the elements of this structure are bound. This binding aspect of the Good is by no means a simple binding of all knowledges or all the objects of knowledge, but the most complicated kind of binding as it is expected from the author of the Republic. The kind of unity the Good gives to the different knowledges of different things is comparable with the unity which each Form gives to its participants in Republic: as all the participants of a Form are united by referring to the ideas, all different kinds of knowledge are united by referring to the Good. If we observe Aristotle's assertion that for Plato and the believers of Forms, the causative relation of the One with the Forms is the same as that of the Forms with particulars (e.g. Metaphysics 988a10-11, 988b4), that is to say the One is the essence (e.g., ibid, 988a10-11: τοῦ τί ἐστὶν, 988b4-6: τὸ τί ἢν εἶναί) of the Forms besides his statement that for them One is the Good (e.g., ibid, 988b11-13) the relation between the Good and unity may become more understandable. Since the quiddity of the Good (τί ποτ᾽ ἐστὶ τἀγαθὸν) is more than discussion (506d8-e2), we cannot await Socrates to tell us how this binding role is played. All we can expect is to hear from him an analogy by which this unifying role is envisaged, the sun. The kind of unity that the Good gives to the knowledge and its objects in the intelligible realm is comparable to the unity that the sun gives to the sight and its objects in the visible realm (508b-c). The allegory of Line (Republic VI, 509d-511), like that of the Sun, tries to bind all various kinds of knowledges. The hierarchical model of the Line which encompasses all kinds of knowledge from imagination to understanding can clearly be considered as Plato’s effort to bind all kinds of knowledges by a certain unhypothetical principle. The method of hypothesis starts, in the first subsection of the intelligible realm, with a hypothesis that is not directed firstly to a principle but a conclusion (510b4-6). It proceeds, in the other subsection, to a 'principle which is not a hypothesis' (b7) and is called the 'unhypothetical principle of all things' (ἀνυποθέτου ἐπὶ τὴν τοῦ παντὸς ἀρχὴν) (511b6-7). This παντὸς must refer not only to the objects of the intelligible realm but to the sensible objects as well. Plato does posit, therefore, an epistemological principle for all things, a principle that all things are, epistemologically, bound and, thus, unified by. -/- 5. Bound Beings The ontological aspect of BK we shall call the principle of 'Bound Beings' (BB): -/- BB Being of all things are bound by the Good. -/- We saw in our principle of Split Being (SB) how the first Socrates was criticized because of his approach to split being and separate each thing from other things. The principle of Bound Beings intends to make the things more related, a duty which is done again by the Good. In the allegory of Sun, there are two paragraphs that evidently and deliberately extend the binding role of the Good to the ontological scene: -/- You will say that the sun not only makes the visible things have the ability of being seen but also coming to be, growth and nourishment. (509b2-4) -/- This clearly intends to remind the ontological role the sun plays in bringing to being all the sensible things in order to display how its counterpart has the same role in the intelligible realm (b6-10): -/- Not only the objects of knowledge (γιγνωσκομένοις) owe their being known (γιγνώσκεσθαι) to the Good, but also their existence (τὸ εἶναί) and their being (οὐσίαν) are due to it, though the Good is not being but superior to it in rank and power. That the Good is here represented as responsible for being of things in addition to their being known means, in my opinion, that Plato wants to posit BB in addition to BK. The allegory of Cave at the very beginning of the seventh Book (514aff.) can be taken as another evidence. The role of the Good, one might say, is confined to the intelligible realm because it is asserted that the role the Good plays in this realm is corresponding to that of the sun in the visible realm. The fact that Plato wants to observe the Good also as the ontological cause of the sensible things is obvious from his saying, in the allegory of Cave, that the Form of the Good 'produces light and its source (τὸν τούτου κύριον) [i.e. the sun] in the visible realm' (517c3). We can conclude, then, that the ontological function of the Good is not confined to the intelligible realm in which it is the lord and provides truth and understanding (c3-4) because it is also responsible to produce τὸν κύριον of light. 6. Proportionality of Being and Knowledge Insofaras BE and BO principles of the first Socrates gave way to TE and TO principles of the second Socrates, we cannot expect him to preserve KB in the same way as it was in the first Socrates. The new tripartite ontology and epistemology necessitates some modifications in KB which results in the principle of 'Proportionality of Being and Knowledge' (PBK): -/- PBK To every class of being there is a proportionate category of knowledge. -/- This principle, of course, does not entail the refutation of KB and thus is not kind of rejecting PBK but only a more complicated version of it. Based on PBK, we can still agree that knowledge is of being (KB) but the issue is that since none of the concepts of knowledge and being in the second Socrates are as simple as they were for the first Socrates, we need a more complicated principle for their relation here. Although from Meno 97a where the distinction of knowledge and true opinion is drawn out in the second group of the dialogues, we can expect a new relation, it is articulated in its most complete way in Republic and specifically in the allegory of Line. All the beings are divided there hierarchically to four classes, to each of them belongs a class of knowledge: imagination to images, belief to the sensible things (more correctly: the things of which they[in previous class] were images (ᾧ τοῦτο ἔοικεν)), thought to mathematical objects (?) and understanding to the Forms and the first principle. The degree of clarity that each of the classes of knowledge shares in (σαφηνείας ἡγησάμενος μετέχειν) is proportionate to the degree that its object shares in truth (ἀληθείας μετέχει). (511e2-4) -/- Conclusion From the six onto-epistemilogical principles of the first Socrates, four principles turn to their opposite in the middle period dialogues. While bipolar epistemology and ontology of the early dialogues give place to tripartite epistemology in the middle period dialogues and tripartite ontology in Republic, the split knowledge and being of the first Socrates are inclined to be substituted by bound knowledges and bound beings in the second Socrates and specifically in Republic. Not all our system of principles in this article is necessarily determinative. Either they are rightly formulated or not, our result would not be vulnerable if we accept that 1) making the distinction of knowledge and belief, 2) accepting the being of not being and 3) trying to bind both being and knowledge by the concept of the Good happens only in middle period dialogues, having been absent in the early ones. These are the favourite results all those somehow arbitrary and even oversimplified principles were to illustrate; that there is kind of a development in the epistemological as well as the ontological grounds of Plato’s philosophy. -/- Notes . (shrink)

Among the cognitive capacities of evolved creatures is the capacity to represent. Theories in cognitive neuroscience typically explain our manifest representational capacities by positing internal representations, but there is little agreement about how these representations function, especially with the relatively recent proliferation of connectionist, dynamical, embodied, and enactive approaches to cognition. In this talk I sketch an account of the nature and function of representation in cognitive neuroscience that couples a realist construal of representational vehicles with a pragmatic account of (...) mental content. I call the resulting package a deflationary account of mental representation and I argue that it avoids the problems that afflict competing accounts. (shrink)

In the philosophy of perception, representationalism is the view that all phenomenological differences among mental states are representational differences, in other words, differences in content. In this paper I defend an alternative view which I call external sortalism, inspired by traditional adverbialism, and according to which experiences are not essentially representational. The central idea is that the external world serves as a model for sorting, conceptualizing, and reasoning surrogatively about perceptual experience. On external sortalism, contents are construed as a kind (...) of gloss on experiences themselves. We can retain what is attractive about representationalism, namely, that perceptual experiences can be evaluated for accuracy, without problematic commitment to the idea that they bear a substantive, representational relation to external objects and properties and that this relation determines the phenomenal character of experience. (shrink)

Much of computational cognitive science construes human cognitive capacities as representational capacities, or as involving representation in some way. Computational theories of vision, for example, typically posit structures that represent edges in the distal scene. Neurons are often said to represent elements of their receptive fields. Despite the ubiquity of representational talk in computational theorizing there is surprisingly little consensus about how such claims are to be understood. The point of this chapter is to sketch an account of the nature (...) and function of representation in computational cognitive models. (shrink)

Introduction: representationalismMost theorists of cognition endorse some version of representationalism, which I will understand as the view that the human mind is an information-using system, and that human cognitive capacities are representational capacities. Of course, notions such as ‘representation’ and ‘information-using’ are terms of art that require explication. As a first pass, representations are “mediating states of an intelligent system that carry information” (Markman and Dietrich 2001, p. 471). They have two important features: (1) they are physically realized, and so (...) have causal powers; (2) they are intentional, in other words, they have meaning or representational content. This presumes a distinction between a representational vehicle—a physical state or structure that has causal powers and is responsible for producing behavior—and its content. Consider the following characterization of a device that computes the addition functionReaders will recognize the similarity t. (shrink)

A very simple contextualist treatment of a sentence containing an epistemic modal, e.g. a might be F, is that it is true iff for all the contextually salient community knows, a is F. It is widely agreed that the simple theory will not work in some cases, but the counterexamples produced so far seem amenable to a more complicated contextualist theory. We argue, however, that no contextualist theory can capture the evaluations speakers naturally make of sentences containing epistemic modals. If (...) we want to respect these evaluations, our best option is a relativist theory of epistemic modals. On a relativist theory, an utterance of a might be F can be true relative to one context of evaluation and false relative to another. We argue that such a theory does better than any rival approach at capturing all the behaviour of epistemic modals. (shrink)

I argue that much current thinking on externalities—at least among “lay political economists” (but even, on occasion, among professional economists)—is saddled with two analytical errors. The first is what I call coextensivism: the conflation of public goods and externalities. The second error is what I call externality profligacy: the conflation of economic and “social” externalities. The principal dangers presented by these two “dogmas on externalities” are that, while in their grips, we are under-disposed to seek negotiated, market-based solutions (of a (...) broadly Coasean nature) to challenges posed by economic externalities, and over-disposed to seek coercive, state-based solutions (of a broadly Pigouvian nature) to challenges posed by social externalities. (shrink)

Artificial intelligence (AI) and robotics are digital technologies that will have significant impact on the development of humanity in the near future. They have raised fundamental questions about what we should do with these systems, what the systems themselves should do, what risks they involve, and how we can control these. - After the Introduction to the field (§1), the main themes (§2) of this article are: Ethical issues that arise with AI systems as objects, i.e., tools made and used (...) by humans. This includes issues of privacy (§2.1) and manipulation (§2.2), opacity (§2.3) and bias (§2.4), human-robot interaction (§2.5), employment (§2.6), and the effects of autonomy (§2.7). Then AI systems as subjects, i.e., ethics for the AI systems themselves in machine ethics (§2.8) and artificial moral agency (§2.9). Finally, the problem of a possible future AI superintelligence leading to a “singularity” (§2.10). We close with a remark on the vision of AI (§3). - For each section within these themes, we provide a general explanation of the ethical issues, outline existing positions and arguments, then analyse how these play out with current technologies and finally, what policy consequences may be drawn. (shrink)

Nicholas Shea offers Varitel Semantics as a naturalistic account of mental content. I argue that the account secures determinate content only by appeal to pragmatic considerations, and so it fails to respect naturalism. But that is fine, because representational content is not, strictly speaking, necessary for explanation in cognitive science. Even in Shea’s own account, content serves only a variety of heuristic functions.

This paper argues that the problematic of rule following in Wittgenstein's Philosophical Investigations and Heidegger's analysis of anxiety in Being and Time have analogous structures. Working through these analogies helps our interpretation of both of these authors. Contrasting sceptical and anti-sceptical readings of Wittgenstein helps us to resolve an interpretive puzzle about what an authentic response to anxiety looks like for Heidegger. And considering the importance of anxiety to Heidegger's conception of authenticity allows us to locate in Wittgenstein's later philosophy (...) a covert appeal to something resembling Heideggerian authenticity. (shrink)

Successful sports teams are able to adopt what is known as the 'we-perspective,' forming intentions and making decisions, somewhat as a unified mind does, to achieve their goals. In this paper I consider what is involved in establishing and maintaining the we-perspective on a racing sailboat. I argue that maintaining the we-perspective contributes to the success of the boat in at least two ways: (1) it facilitates the smooth execution of joint action; and (2) it increases the chance that individual (...) crew members will exert their best effort in fulfilling their particular roles on the boat. (shrink)

The paper offers a solution to the generality problem for a reliabilist epistemology, by developing an “algorithm and parameters” scheme for type-individuating cognitive processes. Algorithms are detailed procedures for mapping inputs to outputs. Parameters are psychological variables that systematically affect processing. The relevant process type for a given token is given by the complete algorithmic characterization of the token, along with the values of all the causally relevant parameters. The typing that results is far removed from the typings of folk (...) psychology, and from much of the epistemology literature. But it is principled and empirically grounded, and shows good prospects for yielding the desired epistemological verdicts. The paper articulates and elaborates the theory, drawing out some of its consequences. Toward the end, the fleshed-out theory is applied to two important case studies: hallucination and cognitive penetration of perception. (shrink)

In my article "Even if the fetus is not a person, abortion is immoral: The impairment argument" (this journal), I defended what I called “The impairment argument” which purports to show that abortion is immoral. Bruce Blackshaw (2019) has argued that my argument fails on three accounts. In this article, I respond to his criticisms.

Representationalism, in its most widely accepted form, is the view that the human mind is an information-using system, and that human cognitive capacities are to be understood as representational capacities. This chapter distinguishes several distinct theses that go by the name "representationalism," focusing on the view that is most prevalent in cogntive science. It also discusses some objections to the view and attempts to clarify the role that representational content plays in cognitive models that make use of the notion of (...) representation. (shrink)

Artificial intelligence research and regulation seek to balance the benefits of innovation against any potential harms and disruption. However, one unintended consequence of the recent surge in AI research is the potential re-orientation of AI technologies to facilitate criminal acts, term in this article AI-Crime. AIC is theoretically feasible thanks to published experiments in automating fraud targeted at social media users, as well as demonstrations of AI-driven manipulation of simulated markets. However, because AIC is still a relatively young and inherently (...) interdisciplinary area—spanning socio-legal studies to formal science—there is little certainty of what an AIC future might look like. This article offers the first systematic, interdisciplinary literature analysis of the foreseeable threats of AIC, providing ethicists, policy-makers, and law enforcement organisations with a synthesis of the current problems, and a possible solution space. (shrink)

Leuridan (2011) questions whether mechanisms can really replace laws at the heart of our thinking about science. In doing so, he enters a long-standing discussion about the relationship between the mech-anistic structures evident in the theories of contemporary biology and the laws of nature privileged especially in traditional empiricist traditions of the philosophy of science (see e.g. Wimsatt 1974; Bechtel and Abrahamsen 2005; Bogen 2005; Darden 2006; Glennan 1996; MDC 2000; Schaffner 1993; Tabery 2003; Weber 2005). In our view, Leuridan (...) misconstrues this discussion. His weak positive claim that mechanistic sciences appeal to generalizations is true but uninteresting. His stronger claim, that all causal claims require laws, is unsupported by his arguments. Though we proceed by criticizing Leuridan’s arguments, our greater purpose is to embellish his arguments in order to show how thinking about mechanisms enriches and transforms old philosophical debates about laws in biology and provides new insights into how generalizations afford prediction, explanation and control. (shrink)

Because factory-farmed meat production inflicts gratuitous suffering upon animals and wreaks havoc on the environment, there are morally compelling reasons to become vegetarian. Yet industrial plant agriculture causes the death of many field animals, and this leads some to question whether consumers ought to get some of their protein from certain kinds of non factory-farmed meat. Donald Bruckner, for instance, boldly argues that the harm principle implies an obligation to collect and consume roadkill and that strict vegetarianism is thus immoral. (...) But this argument works only if the following claims are true: all humans have access to roadkill, roadkill would go to waste if those who happen upon it don’t themselves consume it, it’s impossible to harvest vegetables without killing animals, the animals who are killed in plant production are all-things-considered harmed by crop farming, and the best arguments for vegetarianism all endorse the harm principle. As I will argue in this paper, each claim is deeply problematic. Consequently, in most cases, humans ought to strictly eat plants and save the roadkill for cats. (shrink)

Does the content of a physically dangerous job affect the moral permissibility of hiring for that job? To what extent may employers consider costs in choosing workplace safety measures? Drawing on Kantian ethical theory, this article defends two strong ethical standards of workplace safety. First, the content of a hazardous job does indeed affect the moral permissibility of offering it. Unless employees need hazard pay to meet basic needs, it is permissible to offer a dangerous job only if prospective employees (...) have a reason other than hazard pay to choose this job instead of safer alternatives. Second, employers typically cannot justify omitting expensive safety measures by paying employees more, even if employees prefer higher pay to greater safety. Employers offering dangerous jobs must meet these two standards to avoid treating their employees merely as means. (shrink)

In response to the Covid pandemic the Norwegian government put in place the strictest border closures in Norwegian modern history, restricting entry to most foreign nationals. The Prime Minister, Erna Solberg, justified these restrictions with reference to the rise of new Covid variants, and the need to limit visitors to Norway as much as possible. In this paper we critically examine both the justification given for the border closure, and explore the possible adverse effects this closure might bring about. We (...) argue that the recent closures are not morally justified, that they place an unjust burden on transnational citizens and Norwegians with close relations abroad, and that such border closures can have severe impacts for many individuals, on Norway’s international standing and on social cohesion. (shrink)

Inner speech is commonly understood as the conscious experience of a voice within the mind. One recurrent theme in the scientific literature is that the phenomenon involves a representation of overt speech, for example, a representation of phonetic properties that result from a copy of speech instructions that were ultimately suppressed. I propose a larger picture that involves some embodied objects and their misperception. I call it “the Body Error Theory,” or BET for short. BET is a form of illusionism, (...) but the particular version I favor is a cross-modal illusion. Newly described here, my hypothesis is that the experience of inner speech arises from a mix of interoception and audition. Specifically, there is the detection of slight but well-confirmed activities in the speech musculature that occur during inner speech, which helps to transform representations of normal but quiet nonverbal sounds that inevitably occur during inner speech, from breathing to background noise, into a mistaken perception of inner speech. Simply put, activities in the speech musculature mix with sounds to create the appearance of speech sounds, which thus explains the “voice within the mind.” I also show how BET’s cross-modal system fits with standard information processing accounts for speech monitoring and how it accommodates the central insights of leading theories of inner speech. In addition, I show how BET is supported by data from experience-sampling surveys and how it can be empirically tested against its rivals. (shrink)

A common kind of explanation in cognitive neuroscience might be called functiontheoretic: with some target cognitive capacity in view, the theorist hypothesizes that the system computes a well-defined function (in the mathematical sense) and explains how computing this function constitutes (in the system’s normal environment) the exercise of the cognitive capacity. Recently, proponents of the so-called ‘new mechanist’ approach in philosophy of science have argued that a model of a cognitive capacity is explanatory only to the extent that it reveals (...) the causal structure of the mechanism underlying the capacity. If they are right, then a cognitive model that resists a transparent mapping to known neural mechanisms fails to be explanatory. I argue that a functiontheoretic characterization of a cognitive capacity can be genuinely explanatory even absent an account of how the capacity is realized in neural hardware. (shrink)

Comments on Karen Neander's A Mark of the Mental.

Over the centuries, magicians have developed extensive knowledge about the manipulation of the human mind—knowledge that has been largely ignored by psychology. It has recently been argued that this knowledge could help improve our understanding of human cognition and consciousness. But how might this be done? And how much could it ultimately contribute to the exploration of the human mind? We propose here a framework outlining how knowledge about magic can be used to help us understand the human mind. Various (...) approaches—both old and new—are surveyed, in terms of four different levels. The first focuses on the methods in magic, using these to suggest new approaches to existing issues in psychology. The second focuses on the effects that magic can produce, such as the sense of wonder induced by seeing an apparently impossible event. Third is the consideration of magic tricks—methods and effects together—as phenomena of scientific interest in their own right. Finally, there is the organization of knowledge about magic into an informative whole, including the possibility of a science centered around the experience of wonder. (shrink)

The past decade has seen a protracted debate over the semantics of epistemic modals. According to contextualists, epistemic modals quantify over the possibilities compatible with some contextually determined group’s information. Relativists often object that contextualism fails to do justice to the way we assess utterances containing epistemic modals for truth or falsity. However, recent empirical work seems to cast doubt on the relativist’s claim, suggesting that ordinary speakers’ judgments about epistemic modals are more closely in line with contextualism than relativism (...) (Knobe & Yalcin 2014; Khoo 2015). This paper furthers the debate by reporting new empirical research revealing a previously overlooked dimension of speakers’ truth-value judgments concerning epistemic modals. Our results show that these judgments vary systematically with the question under discussion in the conversational context in which the utterance is being assessed. We argue that this ‘QUD effect’ is difficult to explain if contextualism is true, but is readily explained by a suitably flexible form of relativism. (shrink)

We show that early vision can use monocular cues to rapidly complete partially-occluded objects. Visual search for easily detected fragments becomes difficult when the completed shape is similar to others in the display; conversely, search for fragments that are difficult to detect becomes easy when the completed shape is distinctive. Results indicate that completion occurs via the occlusion-triggered removal of occlusion edges and linking of associated regions. We fail to find evidence for a visible filling-in of contours or surfaces, but (...) do find evidence for a "functional" filling-in that prevents the constituent fragments from being rapidly accessed. As such, it is only the completed structures—and not the fragments themselves—that serve as the basis for rapid recognition. (shrink)

Our visual experience of the world is one of diverse objects and events, each with particular colors, shapes, and motions. This experience is so coherent, so immediate, and so effortless that it seems to result from a single system that lets us experience everything in our field of view. But however appealing, this belief is mistaken: there are severe limits on what can be visually experienced. -/- For example, in a display for air-traffic control it is important to track all (...) moving items. For a single item, this can be done without problem. Three or four can also be tracked, although some degree of effort may be needed. As the number is increased further, accurate tracking becomes more and more difficult—and eventually, impossible. Performance is evidently affected by a factor within the observer which enables certain kinds of perception to occur, but is limited in some way. This factor is generally referred to as attention. -/- At various times, attention has been associated with clarity of perception, intensity of perception, consciousness, selection, or the allocation of a limited “resource” enabling various operations (see Hatfield, 1998). During the past several decades, considerable progress has been achieved by focusing on the idea of selection (Broadbent, 1982). In particular, attention can be productively viewed as contingently selective processing. This can be embodied in various ways by various processes—there need not be a single quantity identified with all forms of attention, or a single site where it operates (Allport, 1993; Tsotsos, 2011). Although “paying attention” is often considered to be a unitary operation, it may simply refer to the control of one or more selective processes, ideally in a co-ordinated way. While this view has some cost in terms of conceptual simplicity, it can help make sense of a large set of phenomena. -/- This article surveys several of the major issues in our understanding of attention and how it relates to perception. It focuses on vision, since many—if not all—considerations are similar for all sensory modalities, and the level of understanding achieved in this domain is currently the most advanced. (shrink)

In his latest book, Michael Devitt rejects Chomsky’s mentalist conception of linguistics. The case against Chomsky is based on two principal claims. First, that we can separate the study of linguistic competence from the study of its outputs: only the latter belongs to linguistic inquiry. Second, Chomsky’s account of a speaker’s competence as consisiting in the mental representation of rules of a grammar for his language is mistaken. I shall argue, first, that Devitt fails to make a case for separating (...) the study of outputs from the study of competence, and second, that Devitt mis-characterises Chomsky’s account of competence, and so his objections miss their target. Chomsky’s own views come close to a denial that speaker’s have knowledge of their language. But a satisfactory account of what speakers are able to do will need to ascribe them linguistic knowledge that they use to speak and understand. I shall explore a conception of speaker’s knowledge of language that confirrns Chomsky’s mentalist view of linguistics but which is immune to Devitt’s criticism. (shrink)

There is widespread consensus that present patterns of consumption could lead to the permanent impossibility of maintaining those patterns and, perhaps, the existence of the human race. While many patterns of consumption qualify as ‘sustainable’ there is one in particular that deserves greater attention: virtual consumption. We argue that virtual consumption — the experience of authentic consumptive experiences replicated by alternative means — has the potential to reduce the deleterious consequences of real consumption by redirecting some consumptive behavior from shifting (...) material states to shifting information states. (shrink)

In 2016, a multidisciplinary body of scholars within the International Commission on Stratigraphy—the Anthropocene Working Group—recommended that the world officially recognize the Anthropocene as a new geological epoch. The most contested claim about the Anthropocene, that humans are a major geological and environmental force on par with natural forces, has proven to be a hotbed for discussion well beyond the science of geology. One reason for this is that it compels many natural and social scientists to confront problems and systems (...) that transgress traditional disciplinary boundaries, and as a result, calls for interdisciplinary research are now gaining traction. Proponents of such transgressions have dubbed the new scientific order that will result “Anthropocene Science”, and rhetoric notwithstanding, such discussions exemplify how recent changes within science justify rethinking a prevailing image of how science is done, and with it, the working relationship between scholars in the humanities, natural scientists, and social scientists. (shrink)

This article addresses three questions about well-being. First, is well-being future-sensitive? I.e., can present well-being depend on future events? Second, is well-being recursively dependent? I.e., can present well-being depend on itself? Third, can present and future well-being be interdependent? The third question combines the first two, in the sense that a yes to it is equivalent to yeses to both the first and second. To do justice to the diverse ways we contemplate well-being, I consider our thought and discourse about (...) well-being in three domains: everyday conversation, social science, and philosophy. This article’s main conclusion is that we must answer the third question with no. Present and future well-being cannot be interdependent. The reason, in short, is that a theory of well-being that countenances both future-sensitivity and recursive dependence would have us understand a person’s well-being at a time as so intricately tied to her well-being at other times that it would not make sense to consider her well-being an aspect of her state at particular times. It follows that we must reject either future-sensitivity or recursive dependence. I ultimately suggest, especially in light of arguments based on assumptions of empirical research on well-being, that the balance of reasons favors rejecting future-sensitivity. (shrink)

A look at the dynamical concept of space and space-generating processes to be found in Kant, J.F. Herbart and the mathematician Bernhard Riemann's philosophical writings.

Classically, gratitude is a tri-polar construal, logically ordering a benefactor, a benefice, and a beneficiary in a favour-giving-receiving situation. Grammatically, the poles are distinguished and bound together by the prepositions ”to’ and ”for’; so I call this classic concept ”to-for’ gratitude. Classic religious gratitude follows this schema, with God as the benefactor. Such gratitude, when felt, is a religious experience, and a reliable readiness or ”habit’ of such construal is a religious virtue. However, atheists have sometimes felt an urge or (...) need for an analogous experience and virtue of gratitude, and theists sometimes feel intellectual discomfort with classical theistic gratitude on consideration of the misfortunes that characterize our life along with its blessings. In response, another conception of religious gratitude has been attempted, a construal that lacks the to-for structure. This paper probes the significance of the benefactor for gratitude, both secular and religious, and, with Søren Kierkegaard’s help, some features of the theology of classical religious gratitude that dissolve the problem of misfortunes. (shrink)

Government’s use of imprisonment raises distinctive moral issues. Even if government has broad authority to make and to enforce law, government may not be entitled to use imprisonment as a punishment for all the criminal laws it is entitled to make. Indeed, there may be some serious crimes that it is wrong to punish with imprisonment, even if the conditions of imprisonment are humane and even if no adequate alternative punishments are available.

Florence Ashley has argued that requiring patients with gender dysphoria to undergo an assessment and referral from a mental health professional before undergoing hormone replacement therapy is unethical and may represent an unconscious hostility towards transgender people. We respond, first, by showing that Ashley has conflated the self-reporting of symptoms with self-diagnosis, and that this is not consistent with the standard model of informed consent to medical treatment. Second, we note that the model of informed consent involved in cosmetic surgery (...) resembles the model Ashley defends, and that psychological assessment and referral is recognised as an important aspect of such a model. Third, we suggest that the increased prevalence of psychiatric morbidity in the transgender population arguably supports the requirement of assessment and referral from a mental health professional prior to undergoing HRT. (shrink)

Grete Hermann’s essay “Die naturphilosophischen Grundlagen der Quantenmechanik” has received much deserved scholarly attention in recent years. In this paper, I follow the lead of Elise Crull who sees in Hermann’s work the general outlines of a neo-Kantian interpretation of quantum theory. In full support of this view, I focus on Hermann’s central claim that limited spatio-temporal, and even analogically causal, representations of events exist within an overall relational structure of entangled quantum mechanical states that defy any unified spatio-temporal description. (...) In my view, Hermann also advances an important transcendental argument that perspectival spatio-temporal representations of nature have their foundations in general relational networks that are not spatio-temporal. The key point is that the adoption of a perspectival system within the general network induces the representation but only for that context. These ideas are consistent with a perspectival subject–object principle in Kant and also with Weyl’s work on Lie groups and their representations. (shrink)

Just as humans can draw conclusions responsibly or irresponsibly, so too can computers. Machine learning systems that have been trained on data sets that include irresponsible judgments are likely to yield irresponsible predictions as outputs. In this paper I focus on a particular kind of inference a computer system might make: identification of the intentions with which a person acted on the basis of photographic evidence. Such inferences are liable to be morally objectionable, because of a way in which they (...) are presumptuous. After elaborating this moral concern, I explore the possibility that carefully procuring the training data for image recognition systems could ensure that the systems avoid the problem. The lesson of this paper extends beyond just the particular case of image recognition systems and the challenge of responsibly identifying a person’s intentions. Reflection on this particular case demonstrates the importance (as well as the difficulty) of evaluating machine learning systems and their training data from the standpoint of moral considerations that are not encompassed by ordinary assessments of predictive accuracy. (shrink)

Certain advocates of the so-called “neo-logicist” movement in the philosophy of mathematics identify themselves as “neo-Fregeans” (e.g., Hale and Wright), presenting an updated and revised version of Frege’s form of logicism. Russell’s form of logicism is scarcely discussed in this literature and, when it is, often dismissed as not really logicism at all (in light of its assumption of axioms of infinity, reducibility and so on). In this paper I have three aims: firstly, to identify more clearly the primary meta-ontological (...) and methodological differences between Russell’s logicism and the more recent forms; secondly, to argue that Russell’s form of logicism offers more elegant and satisfactory solutions to a variety of problems that continue to plague the neo-logicist movement (the bad company objection, the embarrassment of richness objection, worries about a bloated ontology, etc.); thirdly, to argue that neo-Russellian forms of logicism remain viable positions for current philosophers of mathematics. (shrink)