II. C. S. Lewis’s argument, and mine
In reading John Beversluis’s new edition of C. S. Lewis and the Search for Rational Religion, it occurred to me that while I have developed Lewis’s argument a great deal, I have not been as explicit as I might have been in delineating exactly how my argument differs from, and develops his. Of course, Lewis didn’t invent the argument, and it has an important predecessor in Arthur Balfour, the Prime Minister-philosopher of the late 19th and early 20th centuries. Lewis’s role was to introduce the argument to a popular audience, and to revise the argument in response to the criticisms of Elizabeth Anscombe. There have been other important contributors to the argument, in particular William Hasker and Alvin Plantinga.
At several points along the way I have introduced some structure to the argument that was not originally present in Lewis. I am certainly following Lewis’s fundamental idea in this, but a number of the nuances in the argument are my own. Explicating exactly what I have done on this might be helpful in understanding my argument.
Naturalism and Supernaturalism
Lewis begins his discussion by distinguishing between naturalism and supernaturalism. A naturalist is someone who thinks that the privilege of “being on its own,” belongs to “the whole show,” in much the way that sovereignty, in a democracy, belongs to the people not to some particular person or group of persons. A supernaturalist thinks that there are certain real things (or One Thing) that have the privilege of existing on their own, and that other objects depend on that for its existence. Further, he distinguished a “strict materialism,” which he thinks can be refuted by the one-line Haldane quote (If my mental processes are determined wholly by the motions of atoms in my brain, then I have no reason to suppose that my beliefs are true, and hence I have no reason for supposing that my brain is made up of atoms.), from naturalism that is not purely materialistic, and must be refuted with a more complex argument. Lewis says that if naturalism is true, there can be no free will, because determinism would be true. He mentions quantum mechanics, but he describes quantum-mechanical indeterminacy as a “threat” to naturalism, in which the “subnatural” can invade nature “from below,” as it were. However, he expresses doubt that this kind of indeterminism will continue to be affirmed by science.
Because of this, Beversluis responds that his argument against naturalism works, if at all, against deterministic forms of naturalism, and unless the naturalism in question is of the determinist variety, Lewis’s argument is not an argument against that. But does determinism really make a difference? In deterministic forms of naturalism, events are guaranteed by the action of non-rational causes. In non-deterministic forms of naturalism, there is brute chance instead of determinism, but do events ever happen because of reasons? It doesn’t seem as if determinism makes a relevant difference.
I think Lewis’s exposition of the naturalist-supernaturalist distinction needs some further development for philosophical argumentation today. I ask the question of whether the basic causes of the universe are mentalistic or non-mentalistic. If the basic causes of the universe are non-mentalistic, then if we have a mentalistic explanation, such as “Smith believes in evolution, in part, because the fossil record supports it,” then there has to be some explanation underlying that one which in non-mentalistic cause-and-effect operation of mindless atoms moving in accordance with the laws of nature is what is happening in the final analysis. On the other hand, if we look at those same atoms from the standpoint of theism, we find that those particles have the powers and liabilities they do because God created them that way. Scratch far enough, and you get a mentalistic explanation, not a non-mentalistic one. It is interesting that when you look at what makes something “material” or “natural,” you end up defining “material” in terms of the absence of mental characteristics. If a naturalistic worldview is true, then reason comes late to the party, when a brain of sufficient sophistication develops. Lewis describes his argument as an argument for supernaturalism, which is fine so long as we understand that by supernatural, what we mean is that it has, at bottom, and not a non-mentalistic explanation. Richard Carrier, perhaps the Argument from Reason’s most prolific critic, puts it this way.
Hence, I propose a general rule that covers all and thus distinguishes naturalism from supernaturalism: If naturalism is true, everything mental is caused by the nonmental, whereas if supernaturalism is true, at least one thing is not.
But what are the characteristic of the mental? I have identified four characteristics of the mental. The first mark of the mental is purpose. For anyone who denies the ultimacy of the mind, an explanation in terms of purposes requires a further nonpurposive explanation to account for the purpose explanation. The second mark is intentionality or aboutness. Genuinely non-mental states are not about anything at all. The third mark is normativity. A normative explanation must be explained in terms of the non-normative, in the mental is not on the ground level of reality. The fourth mark is subjectivity. There is no inner perspective at the physical level.
Hence, a naturalistic view has, on my view, three basic elements. One of them is a mechanistic, that is non-mentalistic, basic level of reality. The second is the doctrine of the causal closure of the physical. This does not require determinism, but what it does require that nothing outside of the physical be in causal connection. The third doctrine, is the doctrine of supervenience. Whatever is not itself physical must in fact, supervene on the physical. Therefore, this conception of reality is one which prohibits skyhooks, that is, anything from a higher level that is not accounted for on the lower level.
Having laid out these elements, we can proceed to consider what I maintain a naturalistic view has difficulty accounting for. We could begin by looking at what human rationality is, or how it is supposed to manifest itself. Atheists very often perceive themselves has having the more rational view. The claim that, instead of believing things on faith, they look at the evidence and believe only what the evidence supports. But let’s take a look at how this works. If someone, let’s say, believes in evolution because they believe the fossil record supports it, that seems to imply that one set of mental events, those involved in examining and evaluating the fossil evidence, helps to bring about that fact that the person believes in evolution. But, it looks as if, at the basic level of analysis, mental states do not play any role qua mental states. What we have to be calling an instance of mental causation has to in fact be an example of physical causation in which the real causes are in the non-mental supervenience base, not amongst the mental states themselves.
In fact, Lewis said that all knowledge, apart from the knowledge of our sensations, is inferred from those sensations. This led Beversluis to presume that his argument is essentially committed to the idea that, for example, our knowledge that there is a tree in the quad which I see, is really inferential knowledge. He points out that Lewis doesn’t really defend this view of sensory knowledge as inferential, and it would be odd for him to construct an argument based on this kind of view. But Lewis did not have to take such a strong view of inferential knowledge in order for his argument to work. What he needs, instead, is simply to argue that inferential knowledge is essential to science, since no modern atheist is going to argue that science does not acquire knowledge at all. If you consider the process of doing a mathematical equation, or basing a belief in evolution on the evidence, you will see that if your worldview says that this never happens, then this is certainly a very serious problem. These seem to be clear cases in which one mental event cause another mental event.