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)

En la obra de Hegel la filosofía de lo bello es eminentemente filosofía del espíritu. Uno de los temas insoslayables acerca de la belleza es su presencia en la naturaleza y en el arte. En las Lecciones de Estética la belleza del arte se pondera como la más excelente. En este punto la postura hegeliana diverge llamativamente de la de Schelling; quien trató explícitamente de la relación de las artes plásticas con la naturaleza, como consta en el texto que lleva (...) este tema por título (generalmente llamado “discurso de la academia”). Su propuesta es clara: la superioridad de la naturaleza frente a las artes plásticas. Lo más interesante de esta disputa no es el desacuerdo en sí mismo, sino las argumentaciones que uno y otro autor alegan a favor de sus tesis respectivas. (cuánto se parece y cuánto divergen) A través de ellas se pueden ver los diversos matices en torno a los conceptos de belleza y de espíritu. A esta cuestión es a lo que se dedicará esta comunicación: a analizar brevemente algunos argumentos de ambos autores acerca de la belleza en la naturaleza y en el arte. A lo largo de este artículo se lleva a cabo una comparación de textos, de algunas discrepancias concretas: en todas ellas lo llamativo es cómo son a la vez tan cercanos y tan contrarios. Tanto para Schelling como para Hegel, la belleza es del espíritu: lo más bello es lo que está penetrado de espíritu y es vivificado por él. Pero más allá de estos principios comunes hay mil matices que acaban desembocando en dos posturas contrapuestas. (shrink)

This is a three-part exchange on the relationship between belief and credence. It begins with an opening essay by Roger Clarke that argues for the claim that the notion of credence generalizes the notion of belief. Julia Staffel argues in her reply that we need to distinguish between mental states and models representing them, and that this helps us explain what it could mean that belief is a special case of credence. Roger Clarke's final essay reflects on the (...) compatibility of the previously discussed views with dualist and monist interpretations of our mental states and our ways of modeling them. (shrink)

Effective Altruism is a social movement which encourages people to do as much good as they can when helping others, given limited money, time, effort, and other resources. This paper first identifies a minimal philosophical view that underpins this movement, and then argues that there is an analogous minimal philosophical view which might underpin Effective Justice, a possible social movement that would encourage promoting justice most effectively, given limited resources. The latter minimal view reflects an insight about justice, and our (...) non-diminishing moral reason to promote more of it, that surprisingly has gone largely unnoticed and undiscussed. The Effective Altruism movement has led many to reconsider how best to help others, but relatively little attention has been paid to the differences in degrees of cost-effectiveness of activities designed to decrease injustice. This paper therefore not only furthers philosophical understanding of justice, but has potentially major practical implications. (shrink)

critical analyses of the arguments and attitudes favoring the various popular datings of the inception of a human being's life.

Philosophers of religion of the Cracow Circle (1934-1944) are the principal precursors of what is now called the analytic philosophy of religion. The widespread claim that the analytic philosophy of religion was from the beginning an Anglo-American affair is an ill-informed one. It is demonstrable that the enterprise, although not the label "analytic philosophy of religion," appeared in Poland in the 1930’s. Józef Bochenski’s postwar work is a development of the Cracow Circle’s prewar work in the analytic philosophy of religion, (...) or at least of important elements of that earlier work. Bochenski’s approach in his ’Logic of Religion’ is quite original and might still be profitably studied and discussed by philosophers of religion of the analytic persuasion. (shrink)

Explaining the behaviour of ecosystems is one of the key challenges for the biological sciences. Since 2000, new-mechanicism has been the main model to account for the nature of scientific explanation in biology. The universality of the new-mechanist view in biology has been however put into question due to the existence of explanations that account for some biological phenomena in terms of their mathematical properties (mathematical explanations). Supporters of mathematical explanation have argued that the explanation of the behaviour of ecosystems (...) is usually provided in terms of their mathematical properties, and not in mechanistic terms. They have intensively studied the explanation of the properties of ecosystems that behave following the rules of a non-random network. However, no attention has been devoted to the study of the nature of the explanation in those that form a random network. In this paper, we cover that gap by analysing the explanation of the stability behaviour of the microbiome recently elaborated by Coyte and colleagues, to determine whether it fits with the model of explanation suggested by the new-mechanist or by the defenders of mathematical explanation. Our analysis of this case study supports three theses: (1) that the explanation is not given solely in terms of mechanisms, as the new-mechanists understand the concept; (2) that the mathematical properties that describe the system play an essential explanatory role, but they do not exhaust the explanation; (3) that a non-previously identified appeal to the type of interactions that the entities in the network can exhibit, as well as their abundance, is also necessary for Coyte and colleagues’ account to be fully explanatory. From the combination of these three theses we argue for the necessity of an integrative pluralist view of the nature of behaviour explanation when this is given by appealing to the existence of a random network. (shrink)

Many healthcare practices expose people to risks of harmful outcomes. However, the major theories of moral philosophy struggle to assess whether, when and why it is ethically justifiable to expose individuals to risks, as opposed to actually harming them. Sven Ove Hansson has proposed an approach to the ethical assessment of risk imposition that encourages attention to factors including questions of justice in the distribution of advantage and risk, people’s acceptance or otherwise of risks, and the scope individuals have to (...) influence the practices that generate risk. This paper investigates the ethical justifiability of preventive healthcare practices that expose people to risks including overdiagnosis. We applied Hansson’s framework to three such practices: an ‘ideal’ breast screening service, a commercial personal genome testing service, and a guideline that lowers the diagnostic threshold for hypertension. The framework was challenging to apply, not least because healthcare has unclear boundaries and involves highly complex practices. Nonetheless, the framework encouraged attention to issues that would be widely recognised as morally pertinent. Our assessment supports the view that at least some preventive healthcare practices that impose risks including that of overdiagnosis are not ethically justifiable. Further work is however needed to develop and/or test refined assessment criteria and guidance for applying them. (shrink)

Vera Zasulich’s shooting of Trepov, a governor of St Petersburg who had ordered the flogging of a political prisoner, in January 1878, catapulted her to international fame as a revolutionary heroine, a reputation that she put to good use by becoming one of the five ‘founding parents’ of Russian Marxism that created the ‘Group for the Emancipation of Labour’ in 1883. But her act of self-sacrifice also triggered, to her dismay, the institutionalisation of individual terrorist tactics in the Russian Populist (...) movement with the creation of the ‘People’s Will’ (Narodnaya Volya) Party in 1879. The organisation went into decline after the killing of Tsar Alexander II in 1881, and Populism itself was increasingly superseded by Marxism as the hegemonic force on the left with the rise of the Russian Social Democratic Labour Party (RSDLP). But individual terrorist tactics reappeared with the creation of the Socialist Revolutionary Party in 1902, prompting Zasulich to write an article for Die neue Zeit, the theoretical organ of German Social Democracy, in which she both condemned the Neo-Populist tendency as deleterious to the rising labour movement and supported the organisational plans for the RSDLP sponsored by the Iskra group, developed at length by Lenin in his book What Is to Be Done?, published in March 1902. This article provides the background to Vera Zasulich’s article ‘The Terrorist Tendency in Russia’ (December 1902), setting it against the history of the Russian revolutionary movement from 1878 to 1902. (shrink)

This paper argues for a treatment of belief as essentially sensitive to certain features of context. The first part gives an argument that we must take belief to be context-sensitive in the same way that assertion is, if we are to preserve appealing principles tying belief to sincere assertion. In particular, whether an agent counts as believing that p in a context depends on the space of alternative possibilities the agent is considering in that context. One and the same doxastic (...) state may amount to belief that p in one context but not another. The second part of the paper gives a formal treatment of doxastic states, according to which belief is context-sensitive along just these lines. The model is applied to characterize (but not to refute) skeptical arguments. (shrink)

The preface paradox does not show that it can be rational to have inconsistent beliefs, because preface writers do not have inconsistent beliefs. I argue, first, that a fully satisfactory solution to the preface paradox would have it that the preface writer's beliefs are consistent. The case here is on basic intuitive grounds, not the consequence of a theory of rationality or of belief. Second, I point out that there is an independently motivated theory of belief – sensitivism – which (...) allows such a solution. I sketch a sensitivist account of the preface writer's doxastic state. (shrink)

Thompson Clarke’s seminal paper “The Legacy of Skepticism” (1972) is notoriously difficult in both substance and presentation. Despite the paper’s importance to skepticism studies in the nearly half-century since its publication, no attempt has been made in the secondary literature to provide an account, based on a close reading of the text, of just what Clarke’s argument is. Furthermore, much of the existing literature betrays (or so it seems to me) fundamental misunderstandings of Clarke’s thought. In this essay, I attempt (...) to explain—concisely but comprehensively—Clarke’s overall argument in “The Legacy of Skepticism.”. (shrink)

Is God a person, like you and me eventually, but only much better and without our human deficiencies? When you read some of the philosophers of religion, including Richard Swinburne, Alvin Plantinga, or Open Theists, God appears as such a person, in a sense closer to Superman than to the Creator of Heaven and Earth. It is also a theory that a Christian pastoral theology today tends to impose, insisting that God is close to us and attentive to all of (...) us. But this modern account of God could be a deep and even tragic mistake. One God in three persons, the formula of the Trinity, does not mean that God is a person. On this matters we need an effort in the epistemology of theology to examine more precisely what we can pretend to know about God, and especially how we could pretend to know that God is person. (shrink)

In her book Michel de Montaigne: Accidental Philosopher, Ann Hartle argues that Montaigne’s thought is dialectical in the Hegelian sense. Unlike Hegel’s progressive dialectic, however, Montaigne’s thought is, according to Hartle, circular in that the reconciliation of opposed terms comes not in the form of a newly emergent term, but in a return to the first term, where the meaning of the first is transformed as a result of its dialectical interaction with the second. This analysis motivates Hartle’s claim that (...) Montaigne is not a skeptic at all, let alone a Pyrrhonian skeptic. In this paper, I argue that Hartle’s circular-dialectical interpretation of Montaigne is not only compatible with Pyrrhonism, but is in fact an ideal model for understanding Sextus Empiricus’s skeptical therapy. (shrink)

Professional Military Ethics Education (PMEE) must transmit and promote military professionalism, so it must continuously.

Contra Michael Walzer and Jeff McMahan, neither classical just war theory nor the contemporary rules of war require or support any notion of combatant moral equality. Nations rightly accept prohibitions against punishing enemy combatants without recognizing any legal or moral right of aggressors to kill. The notion of combatant moral equality has real import only in our interpersonal -- and intrapersonal -- attitudes, since the notion effectively preempts any ground for conscientious objection. Walzer is criticized for over-emphasizing our collective responses (...) to war conduct and slighting our personal, extra-political responses. (shrink)

The appeal to mechanisms in scientific explanation is commonplace in contemporary philosophy of science. In short, mechanists argue that an explanation of a phenomenon consists of citing the mechanism that brings the phenomenon about. In this paper, we present an argument that challenges the universality of mechanistic explanation: in explanations of the contemporary features of the eukaryotic cell, biologists appeal to its symbiogenetic origin and therefore the notion of symbiogenesis plays the main explanatory role. We defend the notion that symbiogenesis (...) is non-mechanistic in nature and that any attempt to explain some of the contemporary features of the eukaryotic cell mechanistically turns out to be at least insufficient and sometimes fails to address the question that is asked. Finally, we suggest that symbiogenesis is better understood as a pragmatic scientific law and present an alternative non-mechanistic model of scientific explanation. In the model we present, the use of scientific laws is supposed to be a minimal requirement of all scientific explanations, since the purpose of a scientific explanation is to make phenomena expectable. Therefore, this model would help to understand biologists’ appeal to the notion of symbiosis and thus is shown to be better, for the case under examination, than the mechanistic alternative. (shrink)

In this paper Animalism is analysed. It will be argued that Animalism is correct in claiming (i) that being of a certain sort of animal S is a fundamental individuative substance sortal concept (animal of the species Homo Sapiens), (ii) that this implies that Animalism is correct in claiming that persons such as us are, by necessity, human beings, (iii) that remaining the same animal is a necessary condition for our identity over time. Contrary to Animalism it will be argued (...) that this does not imply that person should be understood as a phased sortal concept. It will be argued that Animalism rests upon a prior conception of person, and that this implies that person must be understood as a basic substance sortal concept through which we have to individuate ourselves and others. It is further argued that this, together with the insights of Animalism, implies that persons, by necessity, are beings of a biological nature. (shrink)

This essay argues that Schelling's late transition from Negative to Positive Philosophy constitutes a pointed inversion of the path of systematic ascent mapped by Hegel for the first time in the Phenomenology's Preface, which itself establishes Hegel's development out of and beyond Schelling's early philosophy; that a key notion to inspire the Hegelian vision articulated in the Preface returns to cap off the critique implicit in Schelling's late inversion, where this notion emerges from their divergent readings of Aristotle's Metaphysics; and (...) finally, that while Hegel's theorization of the end of all philosophizing represents his innovative enlargement from within the framework he finds in Aristotle, Schelling's vision of this same end facilitates the crisis of reason which opens unto revelation, and so is akin to the vision which carries Aquinas beyond Aristotle, albeit in Schelling's post‐Spinozist mode of thought. (shrink)

Our culture is conflicted about morally judging and condemning. We can't avoid it altogether, yet many layfolk today are loathe to do it for reasons neither they nor philosophers well understand. Their resistance is often confused (by themselves and by theorists) with some species of antiobjectivism. But unlike a nonobjectivist, most people think that (a) for us to judge and condemn is generally (objectively) morally wrong , yet (b) for God to do so is (objectively) proper, and (c) so too (...) for certain persons in certain relations (e.g., self-condemnation, parental child rearing.) Certainly, religious (e.g., Christian) critics of judging and condemning without doubting the objective truth of their tradition's core moral teachings. Most puzzling is that (a) merely judging and condemning in one's heart may be improper, and (b) someone else with no more evidence or expertise might properly judge and condemn the same action. The answer is in condemning's complex structure of presuppostions. Condemning and judging are acts, and attitudes initiated by the act. Condemnation is motivated by two judgments presumed to justify it, a criticism of a target, and a judgment that the criticism justifies some negative response toward the target. Unlike nonpunitive penalties, punishments are motivated and explained by condemnation. Condemnation is an act of a hostile will, wishing some evil for its target, not (just) as a means to some good. Its root is in damning, an act akin to cursing. It declares a degraded status. The hostility makes it harder to justify condemnation than criticism, and punishment than nonpunitive penalties. Condemning claims objectivity and authority. It involves reflexive evaluation, regarding itself justified, approving its hostile feelings toward the target. Condemners presume themselves entitled to sit in judgment, pass judgment, and cast the condemned down. Those presumptions inhere in sitting in judgment, assuming jurisdiction. Unlike mathematical or scientific judgments, passing moral judgment seems to be a political act subject to extraepistemic constraints. "Who are you to judge?" may properly challenge your right to pass judgment. (shrink)

critical analysis of moral status of human beings. Argues that humans have special moral status simply by being members of our species.

Antithetical desires displayed throughout Kierkegaard’s authorship indicate the disjunctive assumption that the individual exists either in a state of increasing autonomy, expressed negatively as striving for freedom from divine constraint, or in a state of self-annihilating submission, expressed positively in terms of kenotic unification. Proximity to the divine thereby entails forfeiture of individuality, contrary to the explicit aim of Kierkegaard’s authorial project, and aversion to materiality. This essay enunciates the conflict (I), traces the crescendo of loss that births the pseudonymous (...) authorship and ends in realized longing for death (II), and approaches a more holistic vision of psycho-spiritual development (III). (shrink)

Between Schelling’s Über Dante in philosophischer Beziehung (1803) and the Dantean drafts of die Weltalter (1811-1815) stand the transitional texts of his middle period, the Philosophie und Religion (1804) and Freiheitsschrift (1809). His short essay on Dante contrasts an ancient conception of the closed cosmos with the modern universe as dynamic and expanding, then claims to extract from the Divine Comedy its eternal, threefold form. This article considers these schemata as they relate to the Philosophie und Religion and the Freiheitsschrift, (...) disclosing an enduring Dantean influence which first predicts, then persists throughout this stage of Schelling’s philosophical development. (shrink)

Critique of prevailing textbook conception of sufficient conditions and necessary conditions as a truth functional relation of material implication (p->q)/(~q->~p). Explanation of common sense conception of condition as correlative of consequence, involving dependence. Utility of this conception exhibited in resolving puzzles regarding ontology, truth, and fatalism.

This article examines the question of whether the atheist and the believer can understand each other, to the point of being friends intellectually. The answer is no. The atheist and the believer can be best enemies, but their epistemic disagreement is definitely radical. For it is not a disagreement on religious belief itself, but about what allows the believer to believe. The article examines some aspects of John Greco’s concept of ”friendly theism’, the discussion of conciliationism and anti-conciliatonism, and the (...) epistemic role of the Holy Spirit. (shrink)

Many think that Pascal’s Wager is a hopeless failure. A primary reason for this is because a number of challenging objections have been raised to the wager, including the “many gods” objection and the “mixed strategy” objection. We argue that both objections are formal, but not substantive, problems for the wager, and that they both fail for the same reason. We then respond to additional objections to the wager. We show how a version of Pascalian reasoning succeeds, giving us a (...) reason to pay special attention to the infinite consequences of our actions. (shrink)

Manifold expressions of a particular critique appear throughout Søren Kierkegaard’s pseudonymous corpus: for Kierkegaard and his pseudonyms faith is categorically not a first immediacy, and it is certainly not the first immediate, the annulment of which concludes the first movement of Hegelian philosophy. Kierkegaard’s pseudonyms make it clear that he holds the Hegelian dogmaticians responsible for the promulgation of this misconception, but when Kierkegaard’s journals and papers are consulted another transgressor emerges: the renowned anti-idealist F.D.E. Schleiermacher. I address the extent (...) to which this particular indictment is justified; over-against Gerhard Schreiber, I argue that this characterization of Schleiermacher’s view of religion is indeed a de facto critique. I begin by presenting and demonstrating the ubiquity of the phenomenon at the heart of Schleiermacher’s conception of perfect God-consciousness, then proceed to apply criticisms raised by Kierkegaardian pseudonyms Judge William, Vigilius Haufniensis, Johannes Climacus, and Anti-Climacus, supplemented with concerns raised by Kierkegaard himself, in order to demonstrate that these criticisms do indeed apply to and problematize Schleiermacher’s view. (shrink)

The Greek constructions of Zoroaster relate to the historical Zoroaster and to the Zoroaster of the Zoroastrian faith in one respect only. The Greeks knew that Zoroaster was the “prophet,” in the sense of the human founder, of the national Persian religion of their times. That, of course, is a cardinal fact, but it is one fact only. For the rest, the Greek Zoroasters — for there were many — were fantasies of their own imaginations. Since the Greeks were a (...) curious and inventive people, these multiple Zoroasters are interesting creations in their own right. Of more importance, they are elements in the “West’s” construction — or misconstruction — of a major “oriental” religion. -/- . (shrink)

A resolution to the Russell Paradox is presented that is similar to Russell's “theory of types” method but is instead based on the definition of why a thing exists as described in previous work by this author. In that work, it was proposed that a thing exists if it is a grouping tying "stuff" together into a new unit whole. In tying stuff together, this grouping defines what is contained within the new existent entity. A corollary is that a thing, (...) such as a set, does not exist until after the stuff is tied together, or said another way, until what is contained within is completely defined. A second corollary is that after a grouping defining what is contained within is present and the thing exists, if one then alters what is tied together (e.g., alters what is contained within), the first existent entity is destroyed and a different existent entity is created. A third corollary is that a thing exists only where and when its grouping exists. Based on this, the Russell Paradox's set R of all sets that aren't members of themselves does not even exist until after the list of the elements it contains (e.g. the list of all sets that aren't members of themselves) is defined. Once this list of elements is completely defined, R then springs into existence. Therefore, because it doesn't exist until after its list of elements is defined, R obviously can't be in this list of elements and, thus, cannot be a member of itself; so, the paradox is resolved. This same type of reasoning is then applied to Godel's first Incompleteness Theorem. Briefly, while writing a Godel Sentence, one makes reference to a future, not yet completed and not yet existent sentence, G, that claims its unprovability. However, only once the sentence is finished does it become a new unit whole and existent entity called sentence G. If one then goes back in and replaces the reference to the future sentence with the future sentence itself, a totally different sentence, G1, is created. This new sentence G1 does not assert its unprovability. An objection might be that all the possibly infinite number of possible G-type sentences or their corresponding Godel numbers already exist somehow, so one doesn't have to worry about references to future sentences and springing into existence. But, if so, where do they exist? If they exist in a Platonic realm, where is this realm? If they exist pre-formed in the mind, this would seem to require a possibly infinite-sized brain to hold all these sentences. This is not the case. What does exist in the mind is the system for creating G-type sentences and their corresponding numbers. This mental system for making a G-type sentence is not the same as the G-type sentence itself just as an assembly line is not the same as a finished car. In conclusion, a new resolution of the Russell Paradox and some issues with proofs of Godel's First Incompleteness Theorem are described. (shrink)

This paper investigates how the simulation of intelligence, an activity that has been considered the notional task of Artificial Intelligence, does not comprise its duplication. Briefly touching on the distinction between conceivability and possibility, and commenting on Ryan’s approach to fiction in terms of the interplay between possible worlds and her principle of minimal departure, we specify verisimilitude in Artificial Intelligence as the accurate resemblance of intelligence by its simulation and, from this characterization, claim the metaphysical impossibility of duplicating intelligence, (...) as neither verisimilarly nor convincingly simulating intelligence involves its duplication. To this end, we argue by a representative case of simulation that, albeit conceivable, Turing’s test for machine intelligence wrongly equates the occurrence of indistinguishable intelligence performance to intelligence duplication, which is grounded in a prima facie conceivable but metaphysically impossible view that separates intelligence from its origin. Finally, we establish the following criterion for evaluating simulation in Artificial Intelligence: simulations succeed in AI if and only if they are able to epistemically persuade human beings that intelligence has been duplicated, that is, if and only if verisimilar simulations can convincingly minimally depart from actual intelligence. (shrink)

On ground shared by environmental hermeneutics, critical social theory, and environmentally minded feminism, this article attempts to conciliate between the nearly antithetical ethical viewpoints of environmental philosophers David Abram and Steven Vogel. It will demonstrate first that Abram’s linguistic arguments for extending ethical considerability to nonhuman nature succumb to two of Vogel’s debilitating critiques, which it labels the social constructivist critique and the discourse ethics critique, and secondly that Abram fails to guard against the problem of human-human oppression. The article (...) also points out, on the other hand, that while Vogel evades the problem of human-human oppression, his view fails to protect against the problem of dangerous anthropocentrism. Operating within the boundaries that Vogel establishes, it will seek to avoid the pitfalls of Abram’s view, to address the underlying ideology that leads to both types of oppression, and to eliminate the problem of dangerous anthropocentrism. To do so it draws upon the arguments of Trish Glazebrook, contending that Abram’s appeals to the “speech” of nature can be more effectively conceptualized as erotic appeals, and that engaging in this call-and-response eros promotes the development of virtues that undermine our current ideology and extend to both the human and the nonhuman. (shrink)

The identity "relation" is misconceived since the syntax of "=" is misconceived as a relative term. Actually, "=" is syncategorematic; it forms (true) sentences with a nonpredicative syntax from pairs of (coreferring) flanking names, much as "&" forms (true) conjunctive sentences from pairs of (true) flanking sentences. In the conaming structure, nothing is predicated of the subject, other than, implicitly, its being so conamed. An identity sentence has both an objectual reading as a necessity about what is named, and also (...) a metalinguistic reading as a contingency about the names. Either way the claim about the subject referent has no extralinguistic content. The necessity of alteridentity (non-self-identity) statements is "lexical", due to contingencies of the names' reference, much like the necessity of analytic statements, due to contingencies of the predicates' sense, and unlike the necessity of logical truths (e.g., self-identities) whose truth is secured by syntax alone. Both alter-identity and analytic sentences are readable as objectual necessities and metalinguistic contingencies. Epistemically, alter-identity statements are not essentially unlike analyticities. "Greece is Hellas"/"g=h" and "Greeks are Hellenes"/"(x)(Gx<=>Hx)" are equally (un)informative; so too for "Azure is cobalt"/"a=c" and "Everything azure is cobalt"/"(x)(Ax<=>Cx)". The real epistemic contrast is between proper names (terms without predicative sense) and terms with a predicative sense (names and predicates of properties). Proper names refer to concrete objects, property names refer to abstract objects. That contrast is metaphysical and thus epistemic. (shrink)

Critical analysis of wide variety of conceptions and justifications of retribution and punishment. Emphasis is on pivotal role of condemnation.

As part of a review symposium on DARWIN'S ARGUMENT BY ANALOGY: FROM ARTIFICIAL TO NATURAL SELECTION (2021), the journal METASCIENCE invited Roger White, Jon Hodge and me to submit a response to the thoughtful commentaries on our book by Andrea Sullivan-Clarke, David Depew and Andrew Inkpen.

Analyses of quotation have assumed that quotations are referring expressions while disagreeing over details. That assumption is unnecessary and unacceptable in its implications. It entails a quasi-Parmenidean impossibility of meaningfully denying the meaningfulness or referential function of anything uttered, for it implies that: 'Kqxf' is not a meaningful expression 'The' is not a referring expression are, if meaningful, false. It also implies that ill formed constructions like: 'The' is 'the' are well formed tautologies. Such sentences make apparent the need for (...) what is commonly explicit, a genuine referring expression, a noun phrase, usually a description, to which the quotation is appositional. A quotation is not itself a word, though it may contain such. The markers signal that the enquoted material is like a sentence-embedded color patch, material displayed to facilitate reference to something identifiable by/with it specified by the noun phrase it subserves. (shrink)

What should be a police department's policies and regulations on the use of deadly force? What is the relevance for this of the state law on capital punishment?

Resolution of Frege's Puzzle by denying that synonym substitution in logical truths preserves sentence sense and explaining how logical form has semantic import. Intensional context substitutions needn't preserve truth, because intercepting doesn't preserve sentence meaning. Intercepting is nonuniformly substituting a pivotal term in syntactically secured truth. Logical sentences and their synonym interceptions share factual content. Semantic content is factual content in synthetic predications, but not logical sentences and interceptions. Putnam's Postulate entails interception nonsynonymy. Syntax and vocabulary explain only the factual (...) content of synthetic predications; extrasentential reality explains their truth. Construction of logical factual content explains logical necessity. Terms retain objectual reference, but logical syntax preempts their function in explaining truth. Grasping the facts GG/gg assert entails understanding this. Understanding what GH states requires some recognition that GH must be true just because GmH, and GmH state an empirical fact. GH is standardly used to express that fact. Church's Test exposes puzzles. QMi sentences, and QTi sentences are metalogical necessities, true by syntax. Intercepting QMi creates empirical QM contingencies. Synonymy turns semantic contingencies into metalogical and lexical necessities. That transformation is syntactic, via the syntactic duality of definite descriptions. GmH is a contingent copredication, and a lexically necessary referential identity with rigidly codesignating indexicals. Metalogical sentences may be about expressional matter or what it expresses. GG has GG's semantic content, but the referent expression switches. Metalogical syntax secures truth by self-referential quotational indexing. Metalogically, referents are identified with intrasentential replica. Extrasentential identifications are metalogically irrelevant. (shrink)

abortion argument and fact-value distinction.

According to theological fictionalism, God has the same status as a fictional character in a novel or a movie. Such a claim has been defended by Robin Le Poidevin on the basis of Kendall Walton’s theory of make believe. But it is not only a philosophical esoteric account of religious beliefs, it is now an exoteric view, sometimes accepted by "believers" themselves, and so could even be considered a postmodern heresy. But theological fictionalism does not work: faith is real assent (...) and not make believe; belief is different from acceptance; belief and faith are dispositional, but make believe seems to presuppose an account of beliefs as occurrent states; we cannot anymore imagine at will than we can believe at will. (shrink)

Seeking to determine what it is that incites Kierkegaard’s enthusiasm during Schelling’s early lectures at Berlin, then what it is that thoroughly extinguishes his hope in months to follow, I establish: first, that the criticisms of Hegel in Schelling’s negative philosophy depend upon Kantian distinctions and reflect Kant’s critical methodology; secondly, that the leveling function Schelling assigns to these distinctions corresponds to the notion of irony as a destructive force found in The Concept of Irony; finally, that Kierkegaard will come (...) to concretize an account that adheres more closely to Kant’s transition from negative to positive than to Schelling’s. (shrink)

Decision-making by a Data and Safety Monitoring Board (DSMB) regarding clinical trial conduct and termination is intricate and largely limited by cases and rules. Decision-making by legal jury is also intricate and largely constrained by cases and rules. In this paper, I argue by analogy that legal decision-making, which strives for a balance between competing demands of conservatism and innovation, supplies a good basis to the logic behind DSMB decision-making. Using the doctrine of precedents in legal reasoning as my central (...) analog will lead us to a decision-theoretic analogy for much more systematic documentation of decisions in clinical trials. My conclusion is twofold: every DSMB decision should articulate a clear general principle (a ratio decidendi) that gives reason for the decision; and all such decisions should be made public. I use Bartha’s (2010) theory of analogical arguments to both frame and assess my argument by analogy. (shrink)

Philippe Huneman has recently questioned the widespread application of mechanistic models of scientific explanation based on the existence of structural explanations, i.e. explanations that account for the phenomenon to be explained in virtue of the mathematical properties of the system where the phenomenon obtains, rather than in terms of the mechanisms that causally produce the phenomenon. Structural explanations are very diverse, including cases like explanations in terms of bowtie structures, in terms of the topological properties of the system, or in (...) terms of equilibrium. The role of mathematics in bowtie structured systems and in topologically constrained systems has recently been examined in different papers. However, the specific role that mathematical properties play in equilibrium explanations requires further examination, as different authors defend different interpretations, some of them closer to the new-mechanistic approach than to the structural model advocated by Huneman. In this paper, we cover this gap by investigating the explanatory role that mathematics play in Blaser and Kirschner’s nested equilibrium model of the stability of persistent long-term human-microbe associations. We argue that their model is explanatory because: i) it provides a mathematical structure in the form of a set of differential equations that together satisfy an ESS; ii) that the nested nature of the ESSs makes the explanation of host-microbe persistent associations robust to any perturbation; iii) that this is so because the properties of the ESS directly mirror the properties of the biological system in a non-causal way. The combination of these three theses make equilibrium explanations look more similar to structural explanations than to causal-mechanistic explanation. (shrink)

Critical analysis of development of concept of jus ante bellum.

Recently the role of ideology and hegemony has received increased attention to explain varying dynamics of diffusion and autocratic cooperation. As a result, patterns of interaction in clusters from regions without hegemony or ideology have been overlooked because their autocracy-toautocracy transitions are no threat to the global status of democracy, even when active regime promotion is very common. This article will apply insights from economic cluster theory to political regimes and introduce a typology to differentiate among clusters. Regime Cluster Theory (...) is the first framework that presents three ideal-types of ideological, hegemonic and biotopical regime clusters. With a new concept of ‘biotopical clusters’ the paper explains the dynamics of clusters in often omitted regions, like in Sub Saharan Africa, Latin America during the Cold War, or Central Asia during the 1990s. RCT offers a dynamic approach to recognize and assess patterns of forcible regime promotion per cluster as well as distinguish between their different diffusion patterns (coercive, voluntary, bounded learning, contagion) in four arenas: institutions, ideas, policy and administrative practices. RCT advances the comparative study of regime promotion and diffusion in various regions of the world and hopes to shed new light on related theories of alliance formation, regional institutionalization, and (conflict) spill-over effects. (shrink)

View more Abstract If logical truth is necessitated by sheer syntax, mathematics is categorially unlike logic even if all mathematics derives from definitions and logical principles. This contrast gets obscured by the plausibility of the Synonym Substitution Principle implicit in conceptions of analyticity: synonym substitution cannot alter sentence sense. The Principle obviously fails with intercepting: nonuniform term substitution in logical sentences. ‘Televisions are televisions’ and ‘TVs are televisions’ neither sound alike nor are used interchangeably. Interception synonymy gets assumed because logical (...) sentences and their synomic interceptions have identical factual content, which seems to exhaust semantic content. However, intercepting alters syntax by eliminating term recurrence, the sole strictly syntactic means of ensuring necessary term coextension, and thereby syntactically securing necessary truth. Interceptional necessity is lexical, a notational artifact. The denial of interception nonsynonymy and the disregard of term recurrence in logic link with many misconceptions about propositions, logical form, conventions, and metalanguages. Mathematics is distinct from logic: its truth is not syntactic; it is transmitted by synonym substitution; term recurrence has no essential role. The ‘=’ of mathematics is an objectual relation between numbers; the ‘=’ of logic marks a syntactic relation of coreferring terms. -/- . (shrink)