(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.
The prevailing assumption is that in addition our unconscious neural activity, there is another part of us where we have conscious thoughts, that gives instructions to our unconscious brains to produce specific actions. So when I choose to pick up my pen, this conscious decision is transmitted to my unconscious neural network activity which somehow, in ways that are opaque to my conscious mind, tells the motor neurons what to do in order to execute the order. This leads to model (B):
(B) conscious thoughts → unconscious neural activity → action
These conscious thoughts are obviously products of the brain too. After all, when we die, our bodies cease to have conscious thoughts. The question is what causes these conscious thoughts to arise? Believers in free will assume the existence of yet another entity called the ‘will’ that acts on our conscious thoughts driving it in the directions that ‘we’ (i.e., our will) want it to go. Thus another element is added to the causal chain (B), with the will driving behavior via conscious thoughts and unconscious neural activity, resulting in the causal chain (C):
(C) will → conscious thoughts → unconscious neural activity → action
Note that chain (A), in which GES created the brain where the unconscious neural activity takes place, is still operational so (A) and (C) are both acting simultaneously and can be combined to give (D):
(D) GES ↓ will → conscious thoughts → unconscious neural activity → action
This is the schematic model of human behavior that has free will embedded in it and to which many subscribe, or would like to subscribe. The ‘will’ is the Ghost in the Machine. It is the ‘I’ that we like to believe represents the ‘real’ us, that makes decisions and is responsible for our actions. Model (D) represents Cartesian dualism is a schematic form. The will acts in the Cartesian Theater.
But now we have to deal with the problem of what caused or created the will and what it is made of. One has the problem of infinite regress unless one arbitrarily asserts that the will is not a product of the brain but somehow magically came into being at some point in our existence (like the ‘soul’), somehow has the ability to direct our conscious thoughts, and is subject to no further causal explanation. This is remarkably similar to the way that religious people think of god and try to elide the question of who created god, what god is made of, and how he interacts with the world, which likely explains why believers in god are also strong believers in free will. Once you are willing to ignore all the difficulties and believe in the unlikely existence of god, believing in free will becomes not only necessary but easy.
It is possible to eliminate this causality problem by saying that what we think of as the will is not a free-standing entity but is also simply a creation of the brain, another product of unconscious neural activity. If so, we would now have a closed causal loop described by (E), that begins and ends with the brain and thus has a purely material basis.
(E) unconscious neural activity → will → conscious thoughts → unconscious neural activity → action
In (E), will and conscious thoughts are both products of the brain and operationally indistinguishable and thus can be combined into one entity. Thus unconscious neural activity gives rise to conscious thoughts/will that in turn transmits decisions back to the unconscious neural activity, thus eliminating the need for the problematic autonomous, non-material, self-creating, independently existing will. In this model, conscious thoughts/will is an emergent property of the brain, so that (E) can be simplified to (F) where,
(F) conscious thoughts/will ↔ unconscious neural activity → action
Note the causal arrow going in both directions. The first sequence (A) of GES → unconscious neural activity → behavior continues to be still present, so that the final model then becomes a completely causal one, consisting of (A) and (F) combined to give (G):
(G) GES ↓ conscious thoughts/will ↔ unconscious neural activity → action
According to model (G), our behavior and all our thoughts and consciousness and perceptions of free will are all caused by our unconscious neural networks that are the products of our genes, environment, and the random (stochastic) events that constitute our personal history.
In this model, there is no need to insert a mysterious non-material entity at any point. The Ghost in the Machine has been exorcised.
But while models are all well and good, we need experiments and evidence to distinguish between the ones that are close to reality and those that are wishful thinking.
Next: What does the evidence tell us?