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)

This article re-examines the theoretical basis for environmental and heritage interpretation in tourist settings in the light of hermeneutic philosophy. It notes that the pioneering vision of heritage interpretation formulated by Freeman Tilden envisaged a broadly educational, ethically informed and transformative art. By contrast, current cognitive psychological attempts to reduce interpretation to the monological transmission of information, targeting universal but individuated cognitive structures, are found to be wanting. Despite growing signs of diversity, this information processing approach to interpretation remains dominant. (...) The article then presents the alternative paradigm of hermeneutics through the works of Schleiermacher, Dilthey, Heidegger and Gadamer, to provide a broader interpretation of interpretation. This not only captures the essence of Tilden’s definition but construes heritage interpretation as a more inclusive, culturally situated, critically reflexive and dialogical practice. (shrink)

Social work is a contested tradition, torn between the demands of social governance and autonomy. Today, this struggle is reflected in the division between the dominant, neoliberal agenda of service provision and the resistance offered by various critical perspectives employed by disparate groups of practitioners serving diverse communities. Critical social work challenges oppressive conditions and discourses, in addition to addressing their consequences in individuals’ lives. However, very few recent critical theorists informing critical social work have advocated revolution. A challenging exception (...) can be found in the work of Cornelius Castoriadis (1922–97), whose explication of ontological underdetermination and creation evades the pitfalls of both structural determinism and post-structural relativism, enabling an understanding of society as the contested creation of collective imaginaries in action and a politics of radical transformation. On this basis, we argue that Castoriadis’s radical-democratic revisioning of revolutionary praxis can help in reimagining critical social work’s emancipatory potential. (shrink)

The term 'fascism' continues to be very much in currency in Philippines society. To the Filipino people, its meaning is often drawn from pained memory of wholesale deprivation of democratic rights and large-scale human rights abuses. Yet, to many, the fear of fascism has still to give way to a deeper understanding of this menace. This may hold true even among those belonging to the progressive movement. One Marxist philosopher and theoretician who gave extended treatment of the issues surrounding the (...) character and conditions giving rise to fascism was Nicos Poulantzas, whose theory is employed here to interrogate the debates about fascism in the post-Marcos Philippines context. (shrink)

Though the realm of biology has long been under the philosophical rule of the mechanistic magisterium, recent years have seen a surprisingly steady rise in the usurping prowess of process ontology. According to its proponents, theoretical advances in the contemporary science of evo-devo have afforded that ontology a particularly powerful claim to the throne: in that increasingly empirically confirmed discipline, emergently autonomous, higher-order entities are the reigning explanantia. If we are to accept the election of evo-devo as our best conceptualisation (...) of the biological realm with metaphysical rigour, must we depose our mechanistic ontology for failing to properly “carve at the joints” of organisms? In this paper, I challenge the legitimacy of that claim: not only can the theoretical benefits offered by a process ontology be had without it, they cannot be sufficiently grounded without the metaphysical underpinning of the very mechanisms which processes purport to replace. The biological realm, I argue, remains one best understood as under the governance of mechanistic principles. (shrink)

Side effects are ubiquitous in medicine and they often play a role in treatment decisions for patients and clinicians alike. Philosophers and health researchers often use side effects to illustrate issues with contemporary medical research and practice. However, technical definitions of ‘side effect’ differ among health authorities. Thus, determining the side effects of an intervention can differ depending on whose definition we assume. Here I review some of the common definitions of side effect and highlight their issues. In response, I (...) offer an account of side effects as jointly (i) unintended and (ii) effects due to the causal capacities or invariances of an intervention. I discuss (i) by examining the intentions or reasons behind therapeutic interventions, and I discuss (ii) by appealing to a manipulationist model of causation. The analysis here highlights that side effects are conceptually distinct from related outcomes like adverse events, adverse drug reactions, and placebo effects. The analysis also allows for reflection on the utility of ‘side effect’ as a technical term in medical research and practice. (shrink)

Composition as identity, as I understand it, is a theory of the composite structure of reality. The theory’s underlying logic is irreducibly plural; its fundamental primitive is a generalized identity relation that takes either plural or singular arguments. Strong versions of the theory that incorporate a generalized version of the indiscernibility of identicals are incompatible with the framework of plural logic, and should be rejected. Weak versions of the theory that are based on the idea that composition is merely analogous (...) to identity are too weak to be interesting, lacking in metaphysical consequence. I defend a moderate version according to which composition is a kind of identity, and argue that the difference is metaphysically substantial, not merely terminological. I then consider whether the notion of generalized identity, though fundamental, can be elucidated in modal terms by reverse engineering Hume’s Dictum. Unfortunately, for realists about possible worlds, such as myself,... (shrink)

Dispositional properties are often referred to as ‘causal powers’, but what does dispositional causation amount to? Any viable theory must account for two fundamental aspects of the metaphysics of causation – the causal complexity and context sensitivity of causal interactions. The theory of mutual manifestations attempts to do so by locating the complexity and context sensitivity within the nature of dispositions themselves. But is this theory an acceptable first step towards a viable theory of dispositional causation? This paper argues that (...) the reconceptualization that the theory entails comes at too high a price, and is an unnecessary step in the wrong direction: these two central aspects concerning the metaphysics of causation can and should be accounted for in a dispositional account of causation without it. (shrink)

Democracy is the central political issue of our age, yet debates over its nature and goals rarely engage with feminist concerns. Now that women have the right to vote, they are thought to present no special problems of their own. But despite the seemingly gender-neutral categories of individual or citizen, democratic theory and practice continues to privilege the male. This book reconsiders dominant strands in democratic thinking - focusing on liberal democracy, participatory democracy, and twentieth century versions of civic republicanism (...) - and approaches these from a feminist perspective. Anne Phillips explores the under-representation of women in politics, the crucial relationship between public and private spheres, and the lessons of the contemporary women's movement as an experience in participatory democracy. (shrink)

Post-market pharmaceutical surveillance or ‘pharmacovigilance’ relies on the reporting of suspected adverse drug reactions to regulatory databases. Recently, more ‘active’ methods that directly involve patients in identifying and reporting suspected adverse drug reactions have been suggested. This is different than traditional ‘passive’ methods, e.g., using databases without contacting patients directly. Though there are benefits to active pharmacovigilance, it is not without its potential risks. Here I highlight one of those risks – the nocebo effect. Nocebo effects are harms that are (...) thought to arise by conditioning or negative expectation. If a patient engaged in active pharmacovigilance is improperly motivated to seek out and report suspected adverse drug reactions, nocebo harms can occur. Not only is this a bioethical concern about harm, but it is also an epistemic or data-quality problem. Since nocebo effects are not due to the pharmacological properties of the drugs under investigation, nocebo effects reported as suspected adverse drug reactions constitute false positives in these databases. (shrink)

The present studies investigate how the intentions of third parties influence judgments of moral responsibility for other agents who commit immoral acts. Using cases in which an agent acts under some situational constraint brought about by a third party, we ask whether the agent is blamed less for the immoral act when the third party intended for that act to occur. Study 1 demonstrates that third-party intentions do influence judgments of blame. Study 2 finds that third-party intentions only influence moral (...) judgments when the agent's actions precisely match the third party's intention. Study 3 shows that this effect arises from changes in participants' causal perception that the third party was controlling the agent. Studies 4 and 5, respectively, show that the effect cannot be explained by changes in the distribution of blame or perceived differences in situational constraint faced by the agent. (shrink)

Recent scientific research has settled on a purely descriptive definition of happiness that is focused solely on agents’ psychological states (high positive affect, low negative affect, high life satisfaction). In contrast to this understanding, recent research has suggested that the ordinary concept of happiness is also sensitive to the moral value of agents’ lives. Five studies systematically investigate and explain the impact of morality on ordinary assessments of happiness. Study 1 demonstrates that moral judgments influence assessments of happiness not only (...) for untrained participants, but also for academic researchers and even in those who study happiness specifically. Studies 2 and 3 then respectively ask whether this effect may be explained by general motivational biases or beliefs in a just world. In both cases, we find evidence against these explanations. Study 4 shows that the impact of moral judgments cannot be explained by changes in the perception of descriptive psychological states. Finally, Study 5 compares the impact of moral and non-moral value, and provides evidence that unlike non-moral value, moral value is part of the criteria that govern the ordinary concept of happiness. Taken together, these studies provide a specific explanation of how and why the ordinary concept of happiness deviates from the definition used by researchers studying happiness. (shrink)

Exploratory experiments are widely characterized as experiments that do not test hypotheses. Experiments that do test hypotheses are characterized as confirmatory experiments. Philosophers have pointed out that research programmes can be both confirmatory and exploratory. However, these definitions preclude single experiments being characterized as both exploratory and confirmatory; how can an experiment test and not test a hypothesis? Given the intuition that some experiments are exploratory, some are confirmatory, and some are both, a recharacterization of the relationship between exploratory and (...) confirmatory experimentation is needed. I discuss ‘phase IV’ trials to show what this recharacterization could look like. Phase IV trials can be exploratory and confirmatory insofar as they concurrently test hypotheses and explore for unforeseen phenomena. Even if it is uncontroversial that a single experiment can have multiple aims, the recharacterization of the relationship between exploratory and confirmatory experimentation is still required for these aims to be held together coherently. I offer an alternative characterization of the relationship between exploratory and confirmatory experimentation where the former remains a distinct kind of experimentation but is not characterized as non-hypothesis-testing. (shrink)

The underreporting of suspected adverse drug reactions hinders pharmacovigilance. Solutions to underreporting are oftentimes directed at clinicians and health care professionals. However, given the recent rise of public inclusion in medical science, solutions may soon begin more actively involving patients. I aim to offer an evaluative framework for future possible proposals that would engage patients with the aim of mitigating underreporting. The framework may also have value in evaluating current reporting practices. The offered framework is composed of three criteria that (...) are bioethical, social-epistemic, and pragmatic: (i) patients should not be exposed to undue harms, e.g., nocebo effects; (ii) data should be collected, analyzed, and communicated prioritizing pharmacovigilance’s aims, i.e., free from industry bias; and (iii) proposals should account for existing and foreseeable pragmatic constraints like clinician ‘buy in’ and existing reporting infrastructure. Proposals to engage patients in pharmacovigilance that fulfil or address these criteria are preferable to those that do not. (shrink)

We claim that scientists working with deep learning (DL) models exhibit a form of pragmatic understanding that is not reducible to or dependent on explanation. This pragmatic understanding comprises a set of learned methodological principles that underlie DL model design-choices and secure their reliability. We illustrate this action-oriented pragmatic understanding with a case study of AlphaFold2, highlighting the interplay between background knowledge of a problem and methodological choices involving techniques for constraining how a model learns from data. Building successful models (...) requires pragmatic understanding to apply modelling strategies that encourage the model to learn data patterns that will facilitate reliable generalisation. (shrink)

According to the proponents of Developmental Systems Theory and the Causal Parity Thesis, the privileging of the genome as “first among equals” with respect to the development of phenotypic traits is more a reflection of our own heuristic prejudice than of ontology - the underlying causal structures responsible for that specified development no more single out the genome as primary than they do other broadly “environmental” factors. Parting with the methodology of the popular responses to the Thesis, this paper offers (...) a novel criterion for ‘causal primacy’, one that is grounded in the ontology of the unique causal role of dispositional properties. This paper argues that, if the genome is conceptualised as realising dispositional properties that are “directed toward” phenotypic traits, the parity of ‘causal roles’ between genetic and extra-genetic factors is no longer apparent, and further, that the causal primacy of the genome is both plausible and defensible. (shrink)

There has been a long history of arguments over whether happiness is anything more than a particular set of psychological states. On one side, some philosophers have argued that there is not, endorsing a descriptive view of happiness. Affective scientists have also embraced this view and are reaching a near consensus on a definition of happiness as some combination of affect and life-satisfaction. On the other side, some philosophers have maintained an evaluative view of happiness, on which being happy involves (...) living a life that is normatively good. Within the context of this debate we consider how people ordinarily understand happiness, and provide evidence that the ordinary understanding of happiness reflects aspects of both evaluative and descriptive views. Similar to evaluative views, normative judgments have a substantive role in the ordinary understanding of happiness. Yet, similar to descriptive views, the ordinary understanding is focused on the person’s psychological states and not the overall life they actually lived. Combining these two aspects, we argue that the ordinary understanding of happiness suggests a novel view on which happiness consists in experiencing positive psychological states when one ought to. This view, if right, has implications for both philosophical and psychological research on happiness. (shrink)

In this paper I consider the merits and motivations for eliminativist error theories of absence causation, such as those offered by Beebee, Varzi, and Mumford. According to such views, there is no causation by absence. Here I argue that, despite of- fering an alternative picture of the practice of citing absences as causes, these views are inadequately motivated. I consider and reject a range of arguments for error-theoretic approaches, including appeals to ontological economy, physicalism and the causal clo- sure of (...) the physical, as well as Mumford’s recent appeal to soft Parmenideanism. I also argue that the arguments in the literature which aim to show that causation by absence is conceptually problematic are less forceful than they might initially appear. The result is that there is no compelling reason yet why we should reject absence causation. (shrink)

This paper investigates the identity and function of τὰ μεταξύ in Aristotle and the Early Academy by focussing primarily on Aristotle’s criticisms of Xenocrates of Chalcedon, the third scholarch of Plato’s Academy and Aristotle’s direct competitor. It argues that a number of passages in Aristotle’s Metaphysics (at Β 2, Μ 1-2, and Κ 12) are chiefly directed at Xenocrates as a proponent of theories of mathematical intermediates, despite the fact that Aristotle does not mention Xenocrates there. Aristotle complains that the (...) advocates for mathematical intermediates produce theories that are ontologically and epistemologically inefficient (related to, but not confined by, the “Uniqueness Problem”); that their so-called “intermediates” feature properties opposed to those of the forms on which those intermediates are thought to depend; and that what is μεταξύ must be between objects of a different genus. In all three cases, Aristotle’s criticisms are shown to be reactions to the metaphysics and cosmology of Xenocrates, especially his doctrine of the intermediary demonic isosceles triangle souls. Xenocrates emerges as a prime candidate for Aristotle’s critique of Platonist τὰ μεταξύ theories – equal to, and possibly even exceeding, Plato as target. (shrink)

A series of recent studies have explored the impact of people's judgments regarding physical law, morality, and probability. Surprisingly, such studies indicate that these three apparently unrelated types of judgments often have precisely the same impact. We argue that these findings provide evidence for a more general hypothesis about the kind of cognition people use to think about possibilities. Specifically, we suggest that this aspect of people's cognition is best understood using an idea developed within work in the formal semantics (...) tradition, namely the notion of modality. On the view we propose, people may have separate representations for physical, moral and probabilistic considerations, but they also integrate these various considerations into a unified representation of modality. (shrink)

The Forrest-Armstrong argument, as reconfigured by David Lewis, is a reductio against an unrestricted principle of recombination. There is a gap in the argument which Lewis thought could be bridged by an appeal to recombination. After presenting the argument, I show that no plausible principle of recombination can bridge the gap. But other plausible principles of plenitude can bridge the gap, both principles of plenitude for world contents and principles of plenitude for world structures. I conclude that the Forrest-Armstrong argument, (...) when fortified in one of these ways, demands that unrestricted recombination be rejected. The appropriate restriction comes from a consideration of what world structures are possible. I argue that, although there are too many worlds to form a set, for any world, the individuals at that world do form a set. To defend it I invoke a principle of Limitation of Size together with an iterative conception of structure. (shrink)

The paper offers a running commentary on ps-Archytas’ On Intellect and Sense Perception (composed ca. 80 BCE), with the aim to provide a clear description of Hellenistic/post-Hellenistic Pythagorean epistemology. Through an analysis of the process of knowledge and of the faculties that this involves, ps-Archytas presents an original epistemological theory which, although grounded in Aristotelian and Platonic theories, results in a peculiar Pythagorean criteriology that accounts for the acquisition and production of knowledge, as well as for the specific competences of (...) each cognitive faculty. (shrink)

Precision medicine functions by grouping patients along genetic, molecular, and related ‘-omics’ factors. This stratification relies on large, growing databases of patient-volunteered information. Both private companies and government bodies incentivize patients to volunteer this genetic information appealing to the creation of collaborative patient partnerships and the concept of empowerment. This paper aims to address two related questions: (1) what is the actual nature of patient participation in precision medicine research? And (2) is this participation in precision medicine research really that (...) empowering for the average patient? I contend that firstly, the nature of this participation is best conceived of as merely contributory. Contributory participation, as it will be shown, falls short of collaboration. The partnership created by participation in precision medicine research is not one of sharing values, equal say in decisions, or shared benefit. Secondly, I contend that there are important caveats to claims that patient participation in precision medicine is empowering. Empowerment is hindered by the type of participation, the practical use or actionability of genetic data, genetic literacy, the cost of precision drugs for patients that qualify for them, and bioethical considerations of informed consent. (shrink)

Although they are continually compositionally reconstituted and reconfigured, organisms nonetheless persist as ontologically unified beings over time – but in virtue of what? A common answer is: in virtue of their continued possession of the capacity for morphological invariance which persists through, and in spite of, their mereological alteration. While we acknowledge that organisms‟ capacity for the “stability of form” – homeostasis - is an important aspect of their diachronic unity, we argue that this capacity is derived from, and grounded (...) in a more primitive one – namely, the homeodynamic capacity for the “specified variation of form”. In introducing a novel type of causal power – a „structural power‟ – we claim that it is the persistence of their dynamic potential to produce a specified series of structurally adaptive morphologies which grounds organisms‟ privileged status as metaphysically “one over many” over time. (shrink)

Estimates of the burden of disease assess the mortality and morbidity that affect a population by producing summary measures of health such as quality-adjusted life years and disability-adjusted life years. These measures typically do not include stillbirths among the negative health outcomes they count. Priority-setting decisions that rely on these measures are therefore likely to place little value on preventing the more than three million stillbirths that occur annually worldwide. In contrast, neonatal deaths, which occur in comparable numbers, have a (...) substantial impact on burden of disease estimates and are commonly seen as a pressing health concern. In this article we argue in favor of incorporating unintended fetal deaths that occur late in pregnancy into estimates of the burden of disease. Our argument is based on the similarity between late-term fetuses and newborn infants and the assumption that protecting newborns is important. We respond to four objections to counting stillbirths: that fetuses are not yet part of the population and so their deaths should not be included in measures of population health; that valuing the prevention of stillbirths will undermine women's reproductive rights; that including stillbirths implies that miscarriages should also be included; and that birth itself is in fact ethically significant. We conclude that our proposal is ethically preferable to current practice and, if adopted, is likely to lead to improved decisions about health spending. (shrink)

As there is currently a neo-Aristotelian revival currently taking place within contemporary metaphysics and dispositions, or causal powers are now being routinely utilised in theories of causality and modality, more attention is beginning to be paid to a central Aristotelian concern: the metaphysics of substantial unity, and the doctrine of hylomorphism. In this paper, I distinguish two strands of hylomorphism present in the contemporary literature and argue that not only does each engender unique conceptual difficulties, but neither adequately captures the (...) metaphysics of Aristotelian hylomorphism. Thus both strands of contemporary hylomorphism, I argue, fundamentally misunderstand what substantial unity amounts to in the hylomorphic framework – namely, the metaphysical inseparability of matter and form. (shrink)

According to dispositionalism, de re modality is grounded in the intrinsic natures of dispositional properties. Those properties are able to serve as the ground of de re modal truths, it is said, because they bear a special relation to counterfactual conditionals, one of truthmaking. However, because dispositionalism purports to ground de re modality only on the intrinsic natures of dispositional properties, it had better be the case that they do not play that truthmaking role merely in virtue of their being (...) embedded in some particular, extrinsic causal context. This paper examines a recent argument against dispositionalism that purports to show that the intrinsicality of that relation cannot be maintained, due to the ceteris paribus nature of the counterfactuals that dispositions make-true. When two prominent responses are examined, both are found wanting: at best, they require unjustified special pleading, and at worst, they amount to little more than ad hoc conceptual trickery. (shrink)

Dave Chappelle took an extended leave from comedy for moral reasons. I argue that, while he had every right to leave comedy because of his moral concerns, he was not obliged to do so. To make this case, I present Chappelle’s argument that the potential negative consequences of his racial humor obliged him to leave. Next, I argue against Chappelle’s argument about avoidable harms as the harms are not his responsibility, he was not being negligent, and the benefits of his (...) humor outweigh the harms. I also argue in support of the intuition that another’s failure of comprehension or moral character, even if that failure will predictably result in harms to others, should not convert moral acts into immoral ones. (shrink)

This article discusses whether a sense of humor is a political virtue. It argues that a sense of humor is conducive to the central political virtues. We must first, however, delineate different types of humor (benevolent or malicious) and the different political virtues (sociability, prudence, and justice) to which they correspond. Generally speaking, a sense of humor is politically virtuous when it encourages good will toward fellow citizens, an awareness of the limits of power, and a tendency not to take (...) oneself too seriously or when it condemns moral or intellectual vice. An analysis of President Donald Trumps deeply flawed sense of humor is used to ground this account. (shrink)

The advent of contemporary evolutionary theory ushered in the eventual decline of Aristotelian Essentialism (Æ) – for it is widely assumed that essence does not, and cannot have any proper place in the age of evolution. This paper argues that this assumption is a mistake: if Æ can be suitably evolved, it need not face extinction. In it, I claim that if that theory’s fundamental ontology consists of dispositional properties, and if its characteristic metaphysical machinery is interpreted within the framework (...) of contemporary evolutionary developmental biology, an evolved essentialism is available. The reformulated theory of Æ offered in this paper not only fails to fall prey to the typical collection of criticisms, but is also independently both theoretically and empirically plausible. The paper contends that, properly understood, essence belongs in the age of evolution. (shrink)

When did kosmos come to mean *the* kosmos, in the sense of ‘world-order’? I venture a new answer by examining later evidence often underutilised or dismissed by scholars. Two late doxographical accounts in which Pythagoras is said to be first to call the heavens kosmos (in the anonymous Life of Pythagoras and the fragments of Favorinus) exhibit heurematographical tendencies that place their claims in a dialectic with the early Peripatetics about the first discoverers of the mathematical structure of the universe. (...) Likewise, Xenophon and Plato refer to ‘wise men’ who nominate kosmos as the object of scientific inquiry into nature as a whole and the cosmic ‘communion’ (koinônia) between all living beings, respectively. Again, later testimonies help in identifying the anonymous ‘wise men’ by associating them with the Pythagoreans and, especially, Empedocles. As Horky argues, not only is Empedocles the earliest surviving source to use kosmos to refer to a harmonic ‘world-order’ and to illustrate cosmic ‘communities’ between oppositional pairs, but also his cosmology realises the mutual correspondence of these aspects in the cycle of love and strife. Thus, if later figures posited Pythagoras as the first to refer to the universal ‘world-order’ as the kosmos, they did so because they believed Empedocles to have been a Pythagorean natural scientist, whose combined focus on cosmology and ethics exemplified a distinctively Pythagorean approach to philosophy. (shrink)

Bill Cosby’s immorality has raised intriguing aesthetic and ethical issues. Do the crimes that he has been convicted of lessen the aesthetic value of his stand-up and, even if we can enjoy it, should we? This article first discusses the intimate relationship between the comedian and audience. The art form itself is structurally intimate, and at the same time the comedian claims to express an authentic self on stage. After drawing an analogy between the question of the moral character of (...) comedians and the aesthetic value of their stand-up and the debate over the ethical criticism of art, this article argues that it is reasonable to find a comedian’s performance less funny, because stand-up’s artistic success relies on this intimacy. It contrasts the comedy of Bill Cosby with that of Louis C.K. C.K.’s moral flaws are much more present in his comedy, and it is therefore more difficult to find him funny. Last, it is ethically permissible to enjoy their comedy, if no harm to others results, both because it does not corrupt the audience’s character and because amusement is valuable. (shrink)

Evolutionary developmental biology represents a paradigm shift in the understanding of the ontogenesis and evolutionary progression of the denizens of the natural world. Given the empirical successes of the evo-devo framework, and its now widespread acceptance, a timely and important task for the philosophy of biology is to critically discern the ontological commitments of that framework and assess whether and to what extent our current metaphysical models are able to accommodate them. In this paper, I argue that one particular model (...) is a natural fit: an ontology of dispositional properties coherently and adequately captures the crucial casual-cum-explanatory role that the fundamental elements of evo-devo play within that framework. (shrink)

Although contemporary metaphysics has recently undergone a neo-Aristotelian revival wherein dispositions, or capacities are now commonplace in empirically grounded ontologies, being routinely utilised in theories of causality and modality, a central Aristotelian concept has yet to be given serious attention – the doctrine of hylomorphism. The reason for this is clear: while the Aristotelian ontological distinction between actuality and potentiality has proven to be a fruitful conceptual framework with which to model the operation of the natural world, the distinction between (...) form and matter has yet to similarly earn its keep. In this chapter, I offer a first step toward showing that the hylomorphic framework is up to that task. To do so, I return to the birthplace of that doctrine - the biological realm. Utilising recent advances in developmental biology, I argue that the hylomorphic framework is an empirically adequate and conceptually rich explanatory schema with which to model the nature of organisms. (shrink)

In this chapter, I survey what I call Lewisian approaches to modality: approaches that analyze modality in terms of concrete possible worlds and their parts. I take the following four theses to be characteristic of Lewisian approaches to modality. (1) There is no primitive modality. (2) There exists a plurality of concrete possible worlds. (3) Actuality is an indexical concept. (4) Modality de re is to be analyzed in terms of counterparts, not transworld identity. After an introductory section in which (...) I motivate analyzing modality in terms of possible worlds, I devote one section to each of these four theses. For each thesis, I take Lewis’s interpretation and defense as my starting point. I then consider and endorse alternative ways of accepting the thesis, some of which disagree substantially with Lewis’s interpretation or defense. There is more than one way to be a Lewisian about modality. (shrink)

Research on the capacity to understand others' minds has tended to focus on representations ofbeliefs,which are widely taken to be among the most central and basic theory of mind representations. Representations ofknowledge, by contrast, have received comparatively little attention and have often been understood as depending on prior representations of belief. After all, how could one represent someone as knowing something if one does not even represent them as believing it? Drawing on a wide range of methods across cognitive science, (...) we ask whether belief or knowledge is the more basic kind of representation. The evidence indicates that nonhuman primates attribute knowledge but not belief, that knowledge representations arise earlier in human development than belief representations, that the capacity to represent knowledge may remain intact in patient populations even when belief representation is disrupted, that knowledge (but not belief) attributions are likely automatic, and that explicit knowledge attributions are made more quickly than equivalent belief attributions. Critically, the theory of mind representations uncovered by these various methods exhibits a set of signature features clearly indicative of knowledge: they are not modality-specific, they are factive, they are not just true belief, and they allow for representations of egocentric ignorance. We argue that these signature features elucidate the primary function of knowledge representation: facilitating learning from others about the external world. This suggests a new way of understanding theory of mind – one that is focused on understanding others' minds in relation to the actual world, rather than independent from it. (shrink)

By means of a comprehensive and penetrating examination of the main elements of Epicurean ethics, Phillip Mitsis forces us to reevaluate this widely misunderstood figure in the history of philosophy.

This chapter pursues an understanding of what Cicero thought 'Italic' philosophy to be, and proceeds to develop a broader account of how Cicero's version compares with the surviving textual evidence and testimonia from the Hellenistic period of the philosophy of the 'Italic' philosophers, including the Lucanians 'Ocellus', 'Eccelus', and 'Aresas/Aesara', and the Rudian Ennius. Special focus is placed on their theories of cosmology, psychology, and law. Collocation of 'Italic' with 'Pythagorean' philosophy of this era aids in building a more comprehensive (...) view of what Hellenistic Pythagoreanism may have looked like. Uploaded here is the pre-publication version; please email me for the printed version. (shrink)

This paper takes up the question of knowing one's general mental traits, including one's goals, beliefs, and motives. One conclusion is that this is a difficult project. The issue of attributing to oneself ulterior or hidden motives is considered.

According to contemporary ‘process ontology’, organisms are best conceptualised as spatio-temporally extended entities whose mereological composition is fundamentally contingent and whose essence consists in changeability. In contrast to the Aristotelian precepts of classical ‘substance ontology’, from the four-dimensional perspective of this framework, the identity of an organism is grounded not in certain collections of privileged properties, or features which it could not fail to possess, but in the succession of diachronic relations by which it persists, or ‘perdures’ as one entity (...) over time. In this paper, I offer a novel defence of substance ontology by arguing that the coherency and plausibility of the radical reconceptualisation of organisms proffered by process ontology ultimately depends upon its making use of the ‘substantial’ principles it purports to replace. (shrink)

This article traces the historical origins of the modern concept of a private inner self., with precursors in Plato and Plotinus, its first full appearance in Augustine, its classic modern form in Locke, and its dissolution in postmodernism. The article elaborates the historical narrative given in my Augustine's Invention of the Inner Self (Oxford University Press, 2000).

Three of the chief questions this essay addresses are: 1. What justifies considering Hegel and Maimonides together in a probe of the philosophical psychology of prophetic intelligence? 2. What bearing does intellectual intuition as Hegel and Maimonides understand it have on prophecy approached from this standpoint? 3. How does the relation between intelligence and intuition and prophecy, when explored in light of the answer to the first two questions, deepen our contemporary understanding of prophecy in ways that are both philosophically (...) and religiously significant? (shrink)

Many contemporary theorists charge that naïve realists are incapable of accounting for illusions. Various sophisticated proposals have been ventured to meet this charge. Here, we take a different approach and dispute whether the naïve realist owes any distinctive account of illusion. To this end, we begin with a simple, naïve account of veridical perception. We then examine the case that this account cannot be extended to illusions. By reconstructing an explicit version of this argument, we show that it depends critically (...) on the contention that perceptual experience is diaphanous, or more minimally and precisely, that there can be no difference in phenomenal properties between two experiences without a difference in the scenes presented in those experiences. Finding no good reason to accept this claim, we develop and defend a simple, naïve account of both veridical perception and illusion, here dubbed Simple, Austere Naïve Realism. (shrink)

It is tempting to dismiss the first half of Unmodern Philosophy and Modern Philosophy. At first blush, it would not seem to be essential to Dewey’s foremost concern to provide a naturalized account of knowing that avoids the hoary philosophical dualisms of body/mind, thing/person, material/ideal, and practical/theoretical. The load-bearing chapters would seem to be in the latter philosophical half in which he takes on the task of developing a positive account rather than the early historical...

Reeder’s article offers a new and intriguing approach to the study of people’s ordinary understanding of freedom and constraint. On this approach, people use information about freedom and constraint as part of a quasi-scientific effort to make accurate inferences about an agent’s motives. Their beliefs about the agent’s motives then affect a wide variety of further psychological processes, including the process whereby they arrive at moral judgments. In illustrating this new approach, Reeder cites an elegant study he conducted a number (...) of years ago (Reeder & Spores, 1983). All subjects were given a vignette about a man who goes with his date to a pizza parlor and happens to come across a box that has been designated for charitable donations. In one condition, the man’s date then requests that he make a donation; in the other, she requests that he steal the money that is already in the box. In both conditions, the man chooses to comply with this request. The key question is how subjects will use his behavior to make inferences about whether he is a morally good or morally bad person. The results revealed a marked difference between conditions. When the man donated to charity, subjects were generally disinclined to conclude that he must have been a morally good person. It is as though they were thinking: ‘He didn’t just do this out of the goodness of his heart. (shrink)

At the beginning of Republic 2 (358e–359b), Plato has Glaucon ascribe a social contract theory to Thrasymachus and ‘countless others’. This paper takes Glaucon’s description to refer both within the text to Thrasymachus’ views, and outside the text to a series of works, most of which have been lost, On Justice or On Law. It examines what is likely to be the earliest surviving work that presents a philosophical defence of law and justice against those who would prefer their opposites, (...) On Excellence by an anonymous author usually referred to as ‘Anonymus Iamblichi’; the views on these topics among the Socratics, including Crito, Simon the Cobbler, Aristippus of Cyrene, and Antisthenes; and Socrates’ debate with Hippias ‘On Justice’ in Xenophon’s Memorabilia (4.4.5–25). Its main contention is that the ‘countless others’ referred to by Glaucon points chiefly, but not solely, to the members of the circle of Socrates, who themselves espoused a range of views on justice and law, and their relations. (shrink)

This paper critically examines the use of the name 'Pseudo-Archytas' to refer to two aspects of the reception of Archytas of Tarentum in antiquity: the 'author-inflection' and the 'authority-inflection'. In order to make progress on our understanding of authority and authorship within the Pythagorean tradition, it attempts to reconstruct Porphyry's views on the importance of Archytas as guarantor of Pythagorean authenticity in the former's lost work On the History of the Philosophers by considering a fragment preserved in Arabic by Ibn (...) Abī Uṣaybi‘a. The article finally argues that a range of problems attend our use of the term 'pseudo-Archytas', which is not fit for purpose when considering the evidence regarding authorship and authority in the Pythagorean tradition. It recommends a more critical approach to the notion of authenticity within the Pythagorean tradition and suggests a new term, 'Archytism', as a more useful point of reference. (shrink)