FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / Analisou-se o legado de Benjamin Libet e o estado atual de seus achados. Os trabalhos de Libet sobre neurofisiologia do ato voluntÃrio provocaram uma intensa discussÃo no campo da filosofia da mente em geral e do livre arbÃtrio em particular. As evidÃncias de seus principais estudos sÃo de que o processo cerebral responsÃvel pelo ato tido como voluntÃrio inicia-se de modo prÃ-consciente. O inÃcio desse processo neural seria definido pelo aparecimento do potencial de prontidÃo em registros eletroencefalogrÃficos. Isso desafia a noÃÃo comum de que o sujeito pode escolher, de modo consciente e livre, sobre o como e quando agir. O cientista defende a ideia de que a possibilidade de se vetar conscientemente o ato que se iniciou inconscientemente pode garantir o exercÃcio do livre arbÃtrio. O indivÃduo teria cerca de 200 milissegundos para usar esse poder de veto antes da concretizaÃÃo da respectiva aÃÃo enquanto tal. Libet procurou elaborar uma teoria filosÃfica de interaÃÃo mente-corpo para compor com seus achados empÃricos o que entendia ser a configuraÃÃo do agir humano e do livre arbÃtrio. As reaÃÃes a esses trabalhos foram considerÃveis. Trata-se de exemplo significativo de interseÃÃo estreita entre o conhecimento filosÃfico e o conhecimento cientÃfico, onde hà tanto a possibilidade de enriquecimento quanto de mal entendidos. Um levantamento do trabalho de Libet e um apanhado dos principais comentadores de suas reflexÃes mostram que a discussÃo foi muito rica e que ainda continua bastante intensa em nossos dias. Os novos mÃtodos de registro de atividade cerebral e as recentes replicaÃÃes do modelo experimental libetiano enfatizam a importÃncia de sua obra. O exame conceitual mais rigoroso e sofisticado de seus achados e de suas anÃlises se mostrou enriquecedor. Algumas de suas conclusÃes estÃo fortalecidas com o tempo, apesar de certos pontos de suas ilaÃÃes se mostrarem mais frÃgeis. Pode-se considerar seu legado como referencial inescapÃvel para qualquer um que se debruce sobre a questÃo do livre arbÃtrio. / Benjamin Libetâs legacy and the current status of his findings were analysed. Libetsâ works on neurophisiology of voluntary act prompted a huge discussion on philosophy of mind in general and specifically on free will. The evidence from his main studies shows that the brain process that is responsible for the so called voluntary act begins preconsciously. The beginning of this neural process would be defined as the appearance of a readiness potential in eletroencephalographics recordings. This defies the common notion that a person can counsciously and freely choose how and when to act. The scientist holds the idea of consciously vetoing the act that has unconsciously begun and thus enable the exercise of free will. One would have about 200 milliseconds to use this veto power before the concrete onset of the respective action. Libet has tried to figure out a philosophic mind-brain interaction theory to compound with his empiric findings and so to shape what he understood as a human action and free will characterization. The reactions to these works were substantial. It seems to be a noticeable example of close interaction between philosophic and scientific knowledge, with a prospect of both enrichment and misunderstandings. A comprehensive review of Libetâs work and the main thinkers who commented on it shows that the discussion was quite rich and still has a great ammount at the present days. New methods of assessing brain activities and the recent replications of Libetâs experimental model emphasize the importance of his work. Some of his conclusions are now strengthened, in spite of the weakening of other points in his argumentations. His legacy can be ultimately regarded as an unavoidable reference to every person who investigates the free will issue.

Magister Artium - MA / According to our ordinary conception of voluntary action, our actions are the causal result of conscious intentions. To take a very basic example: I wish to take a sip of coffee, and I therefore reach out and take hold of the mug. However, studies performed by Libet challenge this ordinary conception. What Libet found in his experiments was that the brain initiates voluntary actions and the person becomes consciously aware of an intention to act only some 400 msec after the brain’s initiation; for instance, my brain has already initiated the process of causing my arm to reach out and take hold of the mug some 400 msec before I am aware that I wish to take a sip of coffee. That is, conscious intention doesn’t appear to precede voluntary action at all – it actually follows it (or follows its initiation, at least), and thus Libet’s studies present a serious challenge to our ordinary conception of voluntary action. This project will investigate whether a particular theory of mind – namely, Armstrong’s Central State Materialism – can cope with the challenge posed by Libet’s studies and salvage our ordinary conception of voluntary action. Armstrong’s theory appears promising in this regard because his account of consciousness and introspection as higher-order states seems to allow room that we will become aware of our willings only after those willings are already initiated.