Can naturalists believe in free will, even if it is compatibilist free will?

C. S. Lewis wrote:

Thus no thoroughgoing Naturalist believes in free will: for free will would mean that human beings have the power of independent action, the power of doing something more or other than what was involved by the total series of events. And any such separate power of originating events is what the naturalist denies. Spontaneity, originality, action “on its own” is a privilege reserved for “the whole show” which he calls Nature.

The reason Lewis seems to be offering for saying that the Naturalist must deny free will doesn’t seem to mainly be that if Naturalism were true, determinism would be true, but he seems rather to be saying that free will involves a kind of independent agency on the part of persons that would be proscribed given naturalism.

In a footnote, John Beversluis replies as follows:

Some contemporary naturalists, for example, Daniel Dennett, John Searle, Jaegwon Kim, and Keith Parsons, reject determinism not only on the level of microparticles but generally and argue that naturalism is compatible with believing that human beings have free will.

I am not sure about these philosophers, and what kind of free will these people believe in. Students of the free will question know that there are two conceptions of free will: a conception compatible with determinism, and a concept that is incompatible with determinism. Daniel Dennett wrote an entire book, Elbow Room: The Varieties of Free Will Worth Wanting, which is well known as a classic defense of the compatibilism. Parsons, however, has argued the compatibility of libertarian free agency with naturalism.

Eventually, I would like to consider the question of whether a thoroughgoing naturalism is compatible with the incompatibilist or libertarian conception of free will. For the purposes of this discussion, however, I want to concede, for the sake of argument, that compatibilism is true, and I will try to show that it is far from clear that a thoroughgoing naturalism is really compatible with free will.

Compatibilist theories of free will trade on the idea that even if determinism is true, the proximate cause of an action can be one’s desire to perform the action. A compatibilist or soft determinist will say emphasize the fact that if you did something, if it is free in the compatibilist sense, you did what you wanted to do. If, say, you robbed the local Bank of America branch, it is not likely to be true that you wanted to be a law-abiding citizen, but the fickle finger of fate grabbed you by the scruff of the neck and made you commit a crime. No, you robbed the bank because, in the words of Willie Sutton, “That’s where the money is."

But notice what is implied in these kinds of theories. First, in order for this theory to be true, desires have to exist. There are naturalistic theories of mind, eliminativist theories, according to which desires are the posits of “folk psychology” and do not in fact exist. Now eliminativists do maintain that a matured neuroscience will replace the terms of folk psychology with successors, but will can the compatibilist theory be fitted in with a successor? Have eliminativists even addressed this issue?

But suppose we accept the existence of desires. In order for the compatibilist theories to work, the desires have to be causally efficacious. It must be the case that my desire for X can cause my action in pursuit of X. But, of course, naturalistic theories of mind, given their commitment to the causal closure of the physical, inevitably face the specter of epiphenomenalism. That is, even if it is thought that beliefs and desires exist on the hypothesis of naturalism, (which, as I have indicated in a previous post, typically involves a commitment to a causally closed mental-free realm and the bottom of everything), how can it be that my desire can cause anything? In other words, in order for a naturalist to even accept a compatibilist theory of free will, they must solve the problem of mental causation. William Hasker and I have argued that naturalists cannot solve the problem of mental causation, and if I have been right in my discussions here, they cannot consistently even believe in compatibilist free will, much less incompatibilist or libertarian free will.

Beversluis, Kim, and C. S. Lewis on causal closure

Here is an interesting passage in Beversluis chapter on the argument from reason:

JB: Naturalists believe that everything that happens within the total system is caused by something internal to it, so that nothing is independent in a way that enables it to escape this vast interlocking causal web. In short, nature is a self-contained and closed system. By "closed" Lewis means causally closed. So defined, naturalism is a form of determinism--the philosophical theory that everything that happens, happens necessarily as a result of antecedent causes given which nothing could else could have happened. So by naturalism, Lewis means deterministic naturalism. thus, he declares, "no thoroughgoing naturalist believes in freee will (M1, 17). It is important to notice that his argument depends on the assumption that there are ony two alternatives: deterministic naturalism and supernaturalism. If other choices exist, the refutation of the former would not entail the truth of hte latter, as Lewis claims it does.

VR: So in this passage Beversluis commits Lewis to understanding naturalism as deterministic, with the implication that forms of naturalism that deny determinism are not naturalistic. Intereesing Lewis does discuss the denial of determinism through quantum-mechanical indeterminism and says that this would be a rejection of strict natruralism but not an affirmation of supernaturalism, since it would admit a Subnatural realm rather than a supernatural realm. I have discussed this in a couple of posts, but what I had not seen before was the fact that Beversluis seems to think that causal closure entails determinsm.

As defined by contemporary philosophers such as Jaegwon Kim, closure does not entail determinism. Kim writes:


JK: The first of these is the principle that the physical world constitutes a causally closed domain. For our purposes we may state it as follows:The causal closure of the physical domain. If a physical event has a cause at t, then it has a physical cause at t.
There is also an explanatory analogue of this principle (but we will make no explicit use of it here): If a physical event has a causal explanation (in terms of an event occurring at t), it has a physical causal explanation (in terms of a physical event at t).8 According to this principle, physics is causally and explanatorily self-sufficient: there is no need to go outside the physical domain to find a cause, or a causal explanation, of a physical event. It is plain that physical causal closure is entirely consistent with mind-body dualism and does not beg the question against dualism as such; it does not say that physical events and entities are all that there are in this world, or that physical causation is all the causation that there is. As far as physical causal closure goes, there may well be entities and events outside the physical domain, and causal relations might hold between these nonphysical items. There could even be sciences that investigate these nonphysical things and events. Physical causal closure, therefore, does not rule out mind-body dualism--in fact, not even substance dualism; for all it cares, there might be immaterial souls outside the spacetime physical world. If there were such things, the only constraint that the closure principle lays down is that they not causally meddle with physical events--that is, there can be no causal influences injected into the physical domain from outside. Descartes's interactionist dualism, therefore, is precluded by physical causal closure; however, Leibniz's doctrine of preestablished harmony and mind-body parallelism, like Spinoza's double-aspect theory,9 are perfectly consistent with it. Notice that neither the mental nor the biological domain is causally closed; there are mental and biological events whose causes are not themselves mental or biological events. A trauma to the head can cause the loss of consciousness and exposure to intense radiation can cause cells to mutate.

VR: In short, the causal closure principle doesn't imply that there are determining physical causes for every event, only that there are no non-physical causes for any event. The argument from reason, on the other hand, if successful, intends to show that there are non-physical causes for the mental states involved in rational inference. The causal closure principle that Kim presents is sufficient to generate argument from reason. If Lewis had had Kim's definition of causal closure to work with, he would not have saddled the naturalist with determinism, but the argument from reason would not have been effected, since if the AFR works, it requires not merely the denial of physical determinism but also of the causal closure principle as defined by Kim.

A theologyweb debate on the AFR

William Lycan reconsiders dualism

HT: John Sabatino