Many thinkers of recent decades have told us that science shows that humans are merely complicated machines, and that our actions are almost totally predetermined by our brain states, themselves predetermined by our genes and environment. It would follow that we are not really culpable for our bad actions or praiseworthy for our good actions. Yet the normal view in the West in most earlier centuries was that each of us is an immaterial soul in causal interaction with a body, and that although our continued existence may depend on the functioning of a body, what we do with it -- how we act-- depends to a considerable extent on our own decisions which are not fully caused by prior brain states. And on that view, one presupposed by the criminal law, we have free will of a kind which makes us morally responsible for our actions. I argue in this book that this older view is the correct one.
We cannot however make much progress in these well explored fields without discussing certain very general preliminary issues of metaphysics and epistemology, often ignored in discussions in the scientific literature. For example, writers consider experimental evidence purporting to show that conscious events are just brain events, or that humans are just bodies, without considering what are, or ought to be, the criteria for one event or substance (that is, a thing such as a human being or a body) being the same event or substance as another event or substance. So chapter 1 of Mind, Brain, and Free Will is devoted to the general issue of what sorts of things there are, and what are the criteria for one such thing being the same as another such thing. Then writers make claims about when a belief such as a belief that our conscious events do not cause brain events is well 'justified' or 'rational' without in this context exploring what in general are the criteria for a belief being justified. So I explore this issue, to the extent needed in order to apply my results to our topic, in chapter 2.
Equipped with important metaphysical and epistemological results, I then come in chapters 3 to 7, to examine the relation of our life of thought and feeling to what happens in our brains and so in our bodies. I argue in chapter 3 that there are two kinds of event in the world-physical events (including brain events) and mental events. Mental events are events to which the subject (the person whose events they are) has privileged access, that is a way of knowing about them not available to others; physical events are events to which no one subject has privileged access. Among mental events are pure mental events, ones which do not include any physical event. Among these are beliefs, thoughts, intentions, desires and sensations, events of which the subject is often conscious and which are then conscious events. I go on in Chapter 4 to argue that not merely do brain events often cause mental events, but mental events (and in particular intentions) often cause brain events, and thereby bodily movements. Many neuroscientists have interpreted the results of recent neuroscientific experiments as showing that our intentions do not cause our brain events. I argue that -- given the results of my chapter 2 -- no experimental results could possibly ever show that; and that very probably our intentions often do cause our brain events.
I go on in chapter 5 to argue that this result that our intentions often cause our brain events needs to be expressed more carefully as the result that we, human beings, not mere events that happen in us, often cause our brain events when they intentionally cause bodily movements. In chapter 6 I go on to argue in favour of 'substance dualism', the view that each human is a pure mental substance, having a soul as their one essential part and a body as a non-essential part; physical properties belong to humans in virtue of belonging to their bodies, and pure mental properties belong to them in virtue of belonging to their souls. Whether or not it is physically or practically possible for the present body of any human to be destroyed and yet for their soul to continue to exist, my claim is that it is compatible with what we essentially are that any human should continue to exist without their present body or any body at all; and so each of us is essentially a pure mental substance.
I argue in Chapter 7 that although we are always influenced by brain or mental events to form the intentions we do, sometimes (and in particular when we are taking difficult moral decisions) no such events fully determine those intentions. We have a certain freedom to form intentions to act independently of all the influences to which we are subject, naturally called 'free will'. I then proceed to argue in Chapter 8 that, given that that is our situation, we are morally responsible for our actions, in the sense that we are guilty and deserving blame for doing what we believe wrong, meritorious and deserving praise for doing what we believe to be good. And over time, by our free actions we can mould our character, so that actions which were almost impossible for us to choose to do, become easy to choose; and ones which previously were very natural choices for us become no longer open to us. So over time in consequence of our choices we may become either naturally good people or naturally bad people.