"The Cardinal Difficulty of Naturalism"?

C. S. Lewis described, in his book Miracles, what he considered to be “The Cardinal Difficulty of Naturalism.” In a naturalistic, materialistic picture, rational human thought is merely the end product of a long chain of evolutionary causes and effects. But, writes Lewis, “an act of knowing must be determined, in a sense, solely by what is known...if it were totally explicable from other sources it would cease to be knowledge.” In other words, if you say “I think X because of my evolutionary history” this means you cannot say “I think X because it is true.” Why? “If causes fully account for a belief, then, since causes work inevitably, the belief would have had to arise whether it had grounds or not.” Consequently, naturalism leaves no room for affirming truths simply because they are true; all knowledge collapses for the naturalist, and his worldview self-destructs.

It’s an interesting argument, but does it work? I hesitate to give it too much weight. Lewis writes as if the evolutionary cause-and-effect process does nothing to differentiate between beliefs based on whether they are true or not (whether they have logical grounds or not). In his view, blind natural selection brings about thoughts with no regard to how true they are, so it “leaves no room” for believing things on rational grounds.

But it is by no means obvious that “believing X because it is true” and “believing X as a result of physical processes” are mutually exclusive, even if the physical processes are deterministic.

A moment’s reflection will convince us of this. We can all affirm, regardless of our worldviews, that the psychological act of making logical deductions can be described in terms of physical processes in the brain. The ideas running through the mind are exact representations of the (largely) deterministic neurological process (perhaps they are even the same thing, although that is another question). That is, abstract logical deductions are in a sense occurring as physical events. So we have in the human brain both an object that runs according to physical laws, and a truth-deducing mechanism, albeit imperfect and flawed.

Are we to throw up our hands in epistemological despair and cry “our thoughts have a physical cause-and-effect history in our bodies, therefore we cannot hold them rationally - science has destroyed itself as a rational endeavor, along with all other human knowledge!”? Surely not.

Doubtless Lewis would be in agreement here, but perhaps maintain that blind, atheistic natural selection eliminates any “left over” room for affirming truths because they are true. But couldn’t the evolutionary process works in such a way that it produces not merely brains that help us survive, but brains that can think rationally, as ours clearly do? Might we not expect natural selection to give us the ability to think rationally and logically precisely because that way of thinking reflects reality accurately?

Alvin Plantinga’s “evolutionary argument against naturalism” is a more recent version of Lewis’ argument. It is unlikely, suggests Plantinga, that true beliefs* would lead to behavior that would help us survive and reproduce. Consequently, the probability of blind natural selection generating true beliefs is low. If we are going to trust our cognitive faculties, we must appeal to some higher power influencing the course of natural selection so that we develop accurate cognitive faculties. Plantinga concludes, contra Dawkins, that "Darwin made it impossible to be an intellectually fulfilled atheist."
*For the sake of argument, we may as well consider the kind of beliefs that don’t seem immediately useful for our survival; for example, atheism, theism, quantum field theory, or the theory of evolution.

But natural selection may still bring about a particular belief or idea or cognitive capability, even if it in turn has no survival value. It may be that natural selection constructed the ability to perceive the world accurately on a more basic sensory level (eg. counting objects, determining distances with simple geometry), which in turn generated, as a byproduct, the ability to think and reason on a higher level. The details of such a hypothetical scheme are beyond me, but it is a question science may yet answer. We cannot say that our ability to understand higher mathematics, or philosophize about the nature of reality, cannot have arisen from evolution, simply because these phenomena have no apparent evolutionary value.

If and how evolution brought these capabilities about is a complex scientific question, and the absence of a complete answer today is no reason to doubt that the gap will be filled eventually. Consequently, we can recognize that our beliefs have a biological history while at the same time affirming them because we think they are true.

If we are too uncritical in accepting evolutionary arguments against atheism, we may end up saying things like “we don’t know how natural selection could have given us brains fit for understanding the universe, so there must be a supernatural power at work.” Perhaps there is a higher power, and perhaps we can learn about this power in other ways. But in the present case, a less hasty response would be “we don’t know how natural selection gave us these remarkable brains, so let’s think about it, come up with a hypothesis, and test it out.” Maybe at the end of the day biologists will find that under no circumstances would natural selection give rise to the kind of accurate cognitive faculties we seem to possess; then we would indeed have an argument, and a very strong one at that. But Nature has surprised us time after time, so let’s not count on it. Let’s not make the “god of the gaps” mistake yet again. As Bonhoeffer said, “we are to find God in what we know, not in what we don't know.”

The kind of God reached by this argument is a grand architect who refines the physical process so our brains turn out to have the desired capabilities. Is he not rather like the “intelligent designer” God who intervenes in the evolutionary process when it can’t get the job done? And the kind of nature (or theologically, creation) assumed is an insufficient one - a nature that needs help from the outside. Isn’t this familiar?

Science has taught us to expect surprises from nature; evolution has proven itself up to the task again and again. And should we not also expect surprises from God? A creation that can give rise to rational beings of its own accord - in a sense, a world that can make itself - is a greater marvel. It is a creation truly other than God, a creation that has “grown up” in a sense, like a child learning to walk on its own feet.