(For previous posts in this series, see here.)

In 1983, Benjamin Libet and his associates did some experiments that were similar to the 1963 Grey Walter experiment but with the added feature that the patients could observe the equivalent of a clock and thus note when they made the decision to act. This enabled a more objective determination of the time when they first had the conscious thought to carry out the action and not depend upon a possibly misleading feeling of surprise to infer the ordering of events.

One of the key original papers was published in the journal Brain (Time of conscious intention to act in relation to onset of cerebral activity (readiness-potential): The unconscious initiation of a freely voluntary act, vol.106, p. 623-642, 1983) which does not seem to be available online but you can read online a later review published by Libet in 1999 (Do we have free will?, Journal of Consciousness Studies, vol. 6, No. 8–9, 1999, pp. 47–57) where he summarizes his findings and its implications for free will.
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(For previous posts in this series, see here.)

In post #6 in this series, I discussed the 1963 Grey Walter experiment in which patients who had electrodes implanted in their brain’s motor cortex that could send a signal to advance a slide were surprised that the projector seemed to anticipate their decision to advance the slide. Does this mean that their unconscious neural activity had decided to advance the slide before telling the conscious brain that it had decided to do so? If so, it seriously undermines the idea of free will. In his book Consciousness Explained (1991, p. 167) which discusses the experiment, Daniel Dennett warns that it is premature to accept this conclusion because it is based on the articulated sense of surprise reported by the patients, and the brain is not the most reliable of historians.
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(For previous posts in this series, see here.)

In the previous post, I provided a schematic description of two models of how the brain works, one with free will and the other without it. The traditional brain model with free will is given by

(D)                                    GES
                                        ↓
will → conscious thoughts → unconscious neural activity → action

Our genes (G), environment (E), and the inherent randomness in the laws of nature (S) all contribute right up to the present instant to the brain’s structure and unconscious neural activity. But in this model, there is a separate branch in which our (uncaused) free will makes decisions first which manifests itself as a conscious thought. In this model there should be a definite temporal sequence in which the act of will occurs first, followed by conscious thoughts, then unconscious brain activity caused by that conscious thought, and finally the action.
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(For previous posts in this series, see here.)

It is time to look at specific models of how the brain works.

In the previous post, I pointed to a paper by biologist Anthony Cashmore which argues that our brains are the product of genes (G), environment (E), and stochastic (i.e., random) processes (S). This GES combination influences the unconscious neural activity in our brains, which in turn gives instructions to the motor neurons that control our actions. So the causal and completely physiological chain goes like (A):

(A) GES → unconscious neural activity → action

The directions of the arrows signify the causal relationships. Our bodies are in a state of constant activity, with hearts beating, blood flowing, digesting food, breathing, secreting chemicals, producing new cells and disposing of old one, and so on, all of which take place without us being aware of it. I think everyone (except those religious people who can’t bear to see god not taking part in every single activity) will accept that our brains control and moderate all this unconscious behavior. What is in dispute is what gets added on to this basic model.
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(For previous posts in this series, see here.)

The possibility of the existence of Lucretian random swerves that destroy determinism received a boost in the early twentieth century with the advent of quantum mechanics and its associated uncertainty principle that eliminated strict classical determinism.

Believers in free will seized on the inherent randomness built into these newly discovered laws of nature to argue that free will could exist and manifest itself at the quantum level. However, as our understanding of quantum mechanics has increased, few scientists seriously accept this possibility anymore because of the many problems such a model has. After all, random processes are, well, random, meaning that they are not subject to being controlled. If indeterminancy at the quantum level is what undermines determinism, what we would have is not free will but what we might call ‘random will’, in the sense that we would be acting according to the random outcomes of quantum level phenomena over which we have no control. Furthermore, while individual quantum events may be completely indeterminate, they do obey laws that enable us to accurately predict statistical outcomes, so these events cannot be truly free. Free will as popularly conceived does not consist of random or statistically predictable behavior but of the ability to deliberate and determine specific outcomes. No mechanism has been proposed to suggest how that might occur.
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(For previous posts in this series, see here.)

Defining what is meant by free will is not easy. In a loose sense it implies a denial of strict determinism, in which all our actions are completely determined by the past and the immediate environment we find ourselves in. The philosopher John Searle describes free will as the belief “that we could often have done otherwise than we in fact did.” In other words, although I am currently sitting at my desk typing, I think I could just as easily stand up and sing or hop around the room or do any other seemingly spontaneous act. My decision to not do so and continue typing seems like a conscious, freely chosen decision that is not entirely pre-ordained. The catch is that it is hard to reject the alternative hypothesis that all the options I considered were already determined by my history and the external stimuli of the moment, as was also my decision as to which option to choose.
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