Why I think the interaction problem is real
|July 13, 2011||Posted by vjtorley under Intelligent Design|
Regular readers of my posts will be aware that I reject materialism. One of the strongest arguments for materialism, however, is that its alternative, dualism, is untenable. The main problem confronting dualism is the “interaction problem”: how can an immaterial mind, which is completely lacking in physical properties, exert any causal influence on the material world? The idea seems to make no sense at all.
In today’s post, I’m going to examine one argument which attempts to dissolve the interaction problem, and explain why I think the argument does not succeed. (I’ll propose a tentative solution in my next post.) According to the solution put forward by Professor Edward Feser, a well-known philosopher of mind, the interaction problem only arises if you think (as Descartes is supposed to have done) that mind and body are two things, and that the former interacts with the latter in a purely mechanical fashion – as if the mind were like a “spiritual billiard ball” that could somehow set “physical billiard balls” (i.e. neurons in the brain) in motion. (Descartes’ actual views are the subject of some debate, but the picture I’ve outlined here is commonly referred to as Cartesian dualism.) Professor Feser objects strongly to the mechanical conception of causality that has dominated philosophy for the last 300 years, because it completely ignores the directedness (or finality) of causal processes, as well as the forms of causal agents, which make them the kinds of entities they are.
While I share Feser’s view that Cartesian dualism is flawed, I disagree with his claim that Aristotle’s hylemorphic dualism (which views the soul as the form of the body and not as a separate entity) automatically dissolves the interaction problem. I shall argue that while minds do not interact with brains, people can and do interact with their brains in a non-physical manner. (Just to be clear, I’m talking about efficient-causal interaction here: I’m claiming that I can cause the neurons in my brain to move, simply by deciding to raise my arm.) If people couldn’t interact with their brains, then their choices would not be able to change the course of events occurring in the outside world, and determinism would be true. Hylemorphic dualism doesn’t tell us how people interact with their brains, so I would regard it as an incomplete solution to the so-called “mind-body problem.” In my next post, I’ll attempt to provide an account of how we can interact with our brains.
Feser is not alone in his view that hylemorphic dualism solves the interaction problem. In their Philosophical Foundations of Neuroscience (Blackwell Publishing, Oxford, 2003), M.R. Bennett and P.M.S. Hacker write:
…[T]he question of how the mind can interact with the body is emphatically not a question that can arise for Aristotle. Within the framework of Aristotelian thought, as we have seen (1.1), the very question is as senseless as the question, “How can the shape of the table interact with the wood of the table?” Aristotle manifestly did not leave this as a problem within his philosophy. (p. 46)
But the analogy of the mind with the shape of a table is flawed. Aristotle himself regarded the mind as capable of performing operations such as thinking, and he seems to have viewed the intellect as an immaterial faculty, although his views on personal immortality remain the subject of considerable debate (De Anima Book III, Parts 4, 5 & 6). The shape of a table, by contrast, has no operations of its own, which are independent of the matter of the table. So with the greatest respect to Bennett and Hacker, Aristotle’s philosophy of mind has its own
Professor Feser argues that the interaction problem disappears when we treat the soul as the form of the body and not as a separate thing. That is, my soul is what makes my body a human body, and not the body of a chimp or some other organism, or a pile of dust. Feser contends that whenever I act, my actions have a final cause (the end I’m trying to achieve), a formal cause (the pattern or structure of the action itself), a material cause (the matter in my body that actually carries out the action) and an efficient cause (whatever it is that makes my body move when I act). Feser contends that when I perform a bodily action such as writing a blog, the movement of neurons in my brain and arm and the attendant flexing of muscles constitute the material cause of my action, and also the efficient cause, presumably because these neurons are the parts of my body whose movements cause my hands to move when I press the keys on my computer. My thoughts and intentions, on the other hand, comprise the formal cause and the final cause of my action: my thoughts give the blog post the “form” or structure that it has as an essay, while my intentions define my purpose for writing the post. In Feser’s own words:
As I move my fingers across the keyboard, then, what is occurring is not the transfer of energy (or whatever) from some Cartesian immaterial substance to a material one (my brain), which sets up a series of neural events that are from that point on “on their own” as it were, with no further action required of the soul. There is just one substance, namely me, though a substance the understanding of which requires taking note of each of its formal-, material-, final- and efficient-causal aspects. To be sure, my action counts as writing a blog post rather than (say) undergoing a muscular spasm in part because of the specific pattern of neural events, muscular contractions, and so forth underlying it. But only in part. Yet that does not mean that there is an entirely separate set of events occurring in a separate substance that somehow influences, from outside as it were, the goings on in the body. Rather, the neuromuscular processes are by themselves only the material-cum-efficient causal aspect of a single event of which my thoughts and intentions are the formal-cum-final causal aspect.
Problem solved? I think not. What’s wrong with this rosy picture? The problem, as I see it, is that it fails to address the question: what is the efficient cause of the movement of neurons in my brain, when I am writing a blog? What makes these neurons move? What pushes them? An obvious answer would be “the soul,” but Professor Feser expressly rules this out:
The soul doesn’t “interact” with the body considered as an independently existing object, but rather constitutes the matter of the human body as a human body in the first place, as its formal (as opposed to efficient) cause.
There are two comments that I would like to make here. The first is that Feser’s remarks address only a crude Cartesian form of dualism, according to which the soul is the efficient cause of movement in the body (which is ontologically distinct from it). However, they overlook the possibility that the soul, which is the form of the body, is also able to act independently of the body’s matter, and cause certain parts of the body (e.g. neurons in the brain) to move. Here, the soul would be acting as an efficient cause as well as a formal cause.
Second, Feser’s solution to the interaction problem ignores the question of whether the cause of the movement of neurons in my brain is a deterministic cause or not. For instance, if outside stimuli impinging on my body cause the neurons in my brain to move, then it seems there is no room for human freedom, as the action of these stimuli can be described in a deterministic fashion on a molecular level. Throwing in a bit of indeterminism at the subatomic level doesn’t seem to help matters, either; it just creates an element of randomness, which is not the same thing as freedom.
It seems to me, then, that in order to restore human freedom, we have to affirm at least two things: we have to say that people can influence their brains, and we have to say that top-down (macro–>micro) causation is real and fundamental. For if causation is always bottom-up (micro–>macro) and never top-down, or alternatively, if top-down causation is real, but only happens because it has already been determined by some preceding occurrence of bottom-up causation, then our actions are simply the product of our body chemistry – in which case they are not free, as they are determined by external circumstances which lie beyond our control. But if top-down causation is real and fundamental, then events occurring at a holistic level – including a person’s choices – can determine events at a microscopic level, such as their neuro-muscular movements.
The position we have now reached, then, is that if we want to defend human freedom, we have to believe that human acts (i.e. actions which are properly ascribed to persons and not to their body parts) can and do influence lower-level actions, which occur at various locations in the human body, such as activities taking place in human cells when they process incoming signals. We also have to say that the operation of cells is not always deterministic, or even generally deterministic with occasional random disturbances, but that fundamental, higher-level actions can shape the behavior of cells.
What might these higher-level actions be? It might seem tempting to say that higher-level bodily actions can bring about lower-level bodily actions. That’s fine, so far as it goes. However, if we are to have genuine freedom, then these higher-level bodily actions must be just as ontologically fundamental as the lower-level bodily actions that they determine. For if these higher-level actions are determined by lower-level bodily actions occurring at a previous time, then we are back at square one again: we are once more the prisoners of our body chemistry, and bottom-up causation rules.
Could a bodily action, even a higher-level one, be free? I would argue that it cannot, for several reasons. I’ll mention just two; Professor Feser has provided many more (see here, here, here, here and here). First, free choices presuppose a capacity for abstract thinking; but a process taking place at a particular point (or set of points) in my body is (by definition) not abstract but concrete; hence a bodily action is incapable of embodying an abstract concept. Second, free choices and the thoughts that accompany them have an inherent meaning, but bodily processes such as neuronal firings are not inherently meaningful; hence a bodily action is incapable of embodying a free choice. I have discussed these arguments elsewhere, so I won’t elaborate on them here.
The position we have now reached is that if we are to defend human freedom, we have to make a third affirmation; we have to affirm that some human actions (thoughts and choices) are non-bodily actions, and that by performing these actions, human beings are capable of influencing events occurring in the cells of their bodies. And since motor movements begin in the brain, we seem to be committed to the proposition that human beings can, by thinking and choosing, influence events in their brains.
This may sound odd. After all, not everyone knows that they even have a brain: many children don’t, and I imagine many people in times past didn’t know, either. How, it might be asked, can I possibly influence my brain simply by deciding to raise my arm, if I am not thinking about my brain as such, or if I don’t even know I have a brain?
The answer, I believe, is that we just have to take it as a basic fact of human nature that whenever I perform the non-bodily action of deciding to move my right arm, region “X” of the motor homunculus in my brain (i.e. the area in my brain which governs right arm movements) is activated, and whenever I decide to move my right leg instead, region “Y” of the motor homunculus in my brain (which governs right leg movements) is activated. “How convenient!” you might say. And it is. Indeed, it’s more than convenient – it’s absolutely extraordinary. If we were not made that way, voluntary action would be impossible. Since the soul is the form of the body only, I cannot will other objects to move; telekinesis is impossible. I can only move my body parts.
So my solution to the interaction problem is simply to say that God has made human beings with certain built-in psycho-physical correspondences between their (immaterial) mental acts of choosing to move different body parts, and the resulting movements of the various regions of the brain which govern these different body parts.
I am of course well aware that the foregoing account of the mechanics of voluntary movement is grossly oversimplified, as it overlooks such things as feedback, forward modeling, fine motor-tuning and proprioception. Many of these features are found even in insects, which are responsive to stimuli and capable of associative learning, but lack sentience. Now if people can voluntarily fine-tune their actions, then of course they need to be aware at a conscious level of what’s happening to their bodies when they move. However, I don’t think that we need to postulate any extra psycho-physical correspondences on that account. At the very most, we might need further correspondences between people’s mental acts of choosing and other parts of their nervous system, besides the motor homunculus in the brain.
So far I have only talked about how I move my body, through my acts of will. What about God? How does He manage to move bodies, if He is a pure spirit? What needs to be kept in mind here is that God keeps bodies in being and is the Author of their very natures. So it is simply inconceivable that they could fail to respond to His will. However, I would like to draw attention to one little-noticed consequence of the fact that God can move bodies at will: it entails that all physical things have non-physical properties. (I owe this insight to Professor David Oderberg.) Each and every physical object has the property that whenever God wills that it should perform some action, it will perform that action. Insofar as this property of the object is a property that refers to an incorporeal Being (God), it is a non-physical property.
I haven’t addressed the scientific question of how freedom is possible in this post, or how I can influence my body without breaking any laws of Nature. That will be the subject of a future post.