Benjamin+Libet+-+Do+We+Have+Free+Will - Journal of...

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Benjamin Libet Do We Have Free Will? I have taken an experimental approach to this question. Freely voluntary acts are pre- ceded by a specific electrical change in the brain (the ‘readiness potential’, RP) that begins 550 ms before the act. Human subjects became aware of intention to act 350–400 ms after RP starts, but 200 ms. before the motor act. The volitional process is therefore initiated unconsciously. But the conscious function could still control the outcome; it can veto the act. Free will is therefore not excluded. These findings put constraints on views of how free will may operate; it would not initiate a voluntary act but it could control performance of the act. The findings also affect views of guilt and responsibility. But the deeper question still remains: Are freely voluntary acts subject to macro- deterministic laws or can they appear without such constraints, non-determined by natural laws and ‘truly free’? I shall present an experimentalist view about these fundamental philosophical opposites. The question of free will goes to the root of our views about human nature and how we relate to the universe and to natural laws. Are we completely defined by the deter- ministic nature of physical laws? Theologically imposed fateful destiny ironically produces a similar end-effect. In either case, we would be essentially sophisticated automatons, with our conscious feelings and intentions tacked on as epiphenomena with no causal power. Or, do we have some independence in making choices and actions, not completely determined by the known physical laws? I have taken an experimental approach to at least some aspects of the question. The operational definition of free will in these experiments was in accord with common views. First, there should be no external control or cues to affect the occurrence or emergence of the voluntary act under study; i.e. it should be endogenous. Secondly, the subject should feel that he/she wanted to do it, on her/his own initiative, and feel he could control what is being done, when to do it or not to do it. Many actions lack this second attribute. For example, when the primary motor area of the cerebral cortex is stimulated, muscle contractions can be produced in certain sites in the body. How- ever, the subject (a neurosurgical patient) reports that these actions were imposed by the stimulator, i.e. that he did not will these acts. And there are numerous clinical dis- orders in which a similar discrepancy between actions and will occurs. These include Journal of Consciousness Studies , 6 , No. 8–9, 1999, pp. 47–57 Journal of Consciousness Studies
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48 B. LIBET Figure 1 Readiness potentials (RP) preceding self-initiated voluntary acts. Each horizontal row is the computer-averaged potential for 40 trials, recorded by a DC system with an active electrode on the scalp, either at the midline-vertex (C z ) or on the left side (contralateral to the performing right hand) approximately over the motor/premotor cortical area that controls the hand (C
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This note was uploaded on 10/19/2011 for the course PHIL 104 taught by Professor Bunzl during the Spring '08 term at Rutgers.

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Benjamin+Libet+-+Do+We+Have+Free+Will - Journal of...

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