The Grand Coherence, Chapter 9: The Hollow Faith of Scientific Materialism

This post is part of the book The Grand Coherence: A Modern Defense of Christianity. For all the links in the book, see this introductory post.

In the last two chapters, I've tried to show how there is a God-sized hole in science's picture of the world. It needs a Big Bang Causer and a Disentropy Supplier and a Fine Tuner of the natural laws to have made the universe so uncannily suitable for life. It probably also needs a Life Shaper, to have first made the amazingly complicated self-replicating metabolic systems and then intermittently to have added infusions of complexity and functionality, though we needn't insist on that point, since we can prove intelligent design from physics if people refuse to accept the proof from biology. But C.S. Lewis didn't know about the Big Bang, or the fine tuning of initial conditions and physical laws to make life possible, or the irreducible complexity of the information-rich macromolecules that form the basis of life. Nonetheless, he still knew perfectly well that scientific materialism is false, because things like free will and ideas and right and wrong are real, but not physical, and even more, because the authority of human reason depends on its having something other than a merely material basis. It's nice for a Christian apologist that so many recent scientific developments are in Christianity's favor, but the strongest arguments against scientific materialism are older and have a quite different basis. To these we know turn.

First, about free will.

Free will was discussed already in chapter 7, where we saw that the Heisenberg uncertainty principle, and quantum mechanics and subatomic randomness generally, make it harder to find footholds in physics for arguments against free will. But scientific materialism still can't really accept it. It is a good example of a phenomenon we know to be real, but for which scientific materialism leaves no room. Science accepts some types of causation and not others. It has gone from assuming used to assume a lawlike determinism throughout nature, to accepting subatomic randomness at the foundation of things, with lawlike determinism emerging at higher levels as microscopic variations cancel out. That required a revolution in physics. But to add free will to the causal mix would not only require another revolution, but make the reduction of all things to a physical basis impossible.

Scientific materialists are proud of rejecting magic and miracles, in the interests of trusting the laws of physics up apply more consistently than that, and of keeping evidentiary standards high, at least for extraordinary claims. What about free will exercised by human beings? There's no way to reduce that to the kinds of entities, protons and electrons and forces and so forth, which science makes the foundations of everything. To add that to the basic list of types of causation is to abandon the whole project of basing one's worldview entirely on science. And so, although they're often reluctant to advertise the fact, scientific materialists essentially have to classify human free will with magic and miracles, as a form of causation that is too odd and anomalous to be accepted in light of what science has revealed about the general nature of the world. The appearance of free will, like seeming incidents of magic and miracles, must be explained away somehow. Free will must be an illusion.

But we know it isn't. Our experience proves every day, every hour, every minute, that we do have free will. There is no more pervasive feature of human experience than free will and choice. Every day of our lives, it’s perfectly plain and indisputable to common sense that lots of things happen precisely and solely because we chose to make them happen. They were neither predetermined nor random. We know that we could have acted differently. So there must be something in us quite different from the deterministic or random order of physical nature, which was the source of these choices. Common sense and religious tradition call this something "mind" or "soul," regard it as non-material or supernatural, and make a sharp, unbridgeable, and very important distinction between people and things. And that fits our daily experience.

The experience of free will is so fundamental that if scientific materialists insist that we deny it, it's hard to see how they could claim a right to appeal to experience for any other purpose. Would they like to prove something to us by means of experiment? But for that, we must trust our observations. And the first thing we observe in this life is that some things happen because we choose to make them happen. If it’s possible for that to be an illusion, then anything else might equally be an illusion, so what authority can any experimental demonstrations of anything have? A mistrust of ourselves so radical that we can doubt free will should really lead immediately and irrevocably to total skepticism.

Moreover, choice is an inescapable ingredient in every experimental design. The only way we can know that more heat or more catalyst caused the chemical reaction in the test tube is that we know the only reason why there was more heat or more catalyst was the scientist’s choice. If the scientist didn’t choose, then whatever external factor caused the scientist to vary the heat may, for all we know, have separately, not through the heat, caused the chemical reaction to take place. As the statisticians emphasize, correlation is not causation. Just because B follows A doesn't mean that B was caused by A. And so many things happen that the number of possible causal links is endless. In order to isolate causation, we need some kind of inside information on the causes of some events. And we have that, because of free will. We know that some things happened just because we chose to do something. And we can compare the events that happen when we choose action x vs. those that happen when we choose action y, confident that the different causal chains began with our different choices. 

From the baby kicking its legs to the great scientist carefully designing an experimental test of a far-reaching and original hypothesis, we learn about causation by choosing and watching. It’s not clear how we would ever have conceived of such a thing as causation at all, if we didn't start with the power to impact the world through our choices. But for that, the flame might follow the match as winter follows summer, a reliable correlation that isn't a cause, and the whole universe might be like a film of a kaleidoscope display, with intricately patterned moving parts dancing a predetermined choreography, with no cause every that universal script. Only by choosing and watching do we discover pervasive, specific causality in the world.

To deny free will also has such subversive ramifications for ethics as to comprise a kind of reductio ad absurdum. We blame evil people for their bad choices, and praise saints and heroes for their good ones. But if there is no free will, they didn't really choose those actions. They just got lucky, or unlucky Circumstances and accidents made Hitler a mass murderer and Mother Theresa a tireless benefactress of the poorest of the poor. So we shouldn't really blame Hitler and praise Mother Theresa, should we? Without free will, all moral judgment loses its justice. But we all go on making moral judgments, so we must believe, deep down, in free will.

I don't actually believe that it's conceivable that one lacks free will. That seems uncharitable to a writer like Sam Harris, the eminent atheist writer and denier of free will, since it basically means he's playacting, or deliberately deluding himself about his own experience. Yet since I know that the nonexistence of my free will is inconceivable for me, the only alternative to questioning Sam Harris's sincerity is to question his humanity, and I won't do that. I don't have introspective access to Sam Harris's subjective experience, so I don't strictly know that Sam Harris isn't an automaton, in the way that I know that I'm not an automaton. But I assume there's a pretty large package of features that go with being human, and form the basis of human dignity, and free will is definitely part of that. So while I can conceive of a world in which Sam Harris is an automaton while I have free will, I'm not willing to entertain that possibility. My principles of human dignity forbid it.

And yet Sam Harris claims that there's experimental evidence against free will. What are we to make of that? I won't try to describe the experiments, because I've never read descriptions of them that make it clear why they're considered convincing, but I have my own evidence to bring, showing that introspection can be mistaken about the scope of free will in small matters. I learned it when a comic hypnotist visited our campus, and introduced his act by having a student volunteer repeatedly to choose which half of a ripped piece of newspaper to throw away, till only one letter remained. He then showed that he had written it down in advance, and manipulated her apparently free choices to get a planned result. I was already a disciple of C.S. Lewis then, and believed in free will in the authority of introspection, so this was deeply shocking for me. 

But on second thought, it's not about such minutiae, about choices that seem random and are completely unimportant, that introspection testifies strongly to the operation of free will. In such minor matters, we often feel like the pawns of what happens to occur to us, the flow of our thoughts, and that's mysterious, and might, for all we can tell, be manipulated from without. It's in morally important choices, where there is deliberation and grave consequences, that the experience of exercising of free will is most intense, and there it is not so easily embarrassed. 

Introspective evidence is in one sense indubitable, and Descartes was wise to begin his philosophy from "I think, therefore I am," setting aside the senses, which can be deceived, in favor of introspection, which is more fundamental. Yet at the same time, introspection is stultifyingly private, and consequently rather untrained and inarticulate. Other people can't look at our inward experiences and teach us how to observe and describe them properly. So while we may trust introspection itself, we need to be wary in framing claims based on it. We may sometimes need help from the external world to help us discern better what's going on inside us. But introspection can't be wrong about something as overwhelmingly clear as the existence of free will.

Just in case you make a hobby out of debating free will with secular friends, it's worth knowing about an annoyingly evasive philosophical position people sometimes take, called "compatibilism." Compatibilists claim that free will is compatible with determinism or randomness, and respond to denials of this absurdity by taking the whole discussion in a merely semantic direction. They ask, "What do people mean when they say 'free will?'" and then argue that what people mean by it is consistent with human choices being determined by natural laws. On that merely semantic question, it's impossible to beat them in the heat of an argument, since it would require, at minimum, a public opinion poll to settle it. The argument can only proceed by taking the rather barren form of rhetoric vs. rhetoric. And that's a victory of sorts, since it turns an attack on one of scientific materialism's most vulnerable points into a stalemate of rhetoric and obfuscation.

Compatibilism is interesting chiefly as evidence of how counterintuitive the denial of free will is, and the lengths to which people philosophically obligated by their broader worldview to deny free will will go in order to avoid denying it openly. The way to rebut compatibilism is to distinguish "compatibilist free will," which is consistent with physicalist determinism, from "incompatibilist free will," which is not. Get them to admit the distinction is conceivable. Then say you believe in incompatibilist free will, and you have no interest in "compatibilist" free will, but only in the question of whether incompatibilist free will exists. You might add that you don't believe for a moment that the expression "free will" as used by most people has a meaning that's compatible with determinism, but for the moment, you don't really care. It should be possible to get most compatibilists to admit that they deny free will "in your sense," and with that, compatibilism is out of the way, and a more relevant debate can ensue.

Ethics can help out more than just as a case study in free will. It also supplies entities, namely, moral right and wrong, evidently real and evidently non-material, which by their existence prove scientific materialism false. C.S. Lewis, in Mere Christianity, began with ethics as a metaphysical problem. He pointed out that every time we quarrel, which is not mere fighting but involves self-justifying attempts to claim the moral high ground, we appeal to moral principles and standards. No normal person really, consistently denies these standards. But in a scientific materialist world, there can be no real ethics, no right and wrong or good and evil. What's the chemical formula of justice? What's the crystallography of hatred, and how many joules of energy comprise cowardice? Such questions are obviously absurd, and at least to that extent, ethics is obviously non-material. Attempts to embed ethics in a scientific materialist conscience inevitably reduce them to instincts and social constructs, undermining the authority that conscience and culture give to the moral law.  "Ethics" rooted in mere genes and neurons is, as the saying goes, all in our heads. But I think we all know that the Holocaust was bad and self-sacrificing heroic actions that save lives are good really, not just in someone's opinion. Right and wrong are real, but they are not material, so scientific materialism is false. 

Again, consider beauty. Something in us wants to say that sunrises and waterfalls and cardinals and Bach chorales are really beautiful, and mutilated corpses and highways besieged with billboards are really ugly. We might, however, be willing to accept the merely subjective character of beauty more easily than we would accept the nonexistence of objective right and wrong, or of free will. I think that would be a mistake, for the integrity of ideas is not ultimately separable from our aesthetic sensibilities, and if we don’t let a faculty akin to the aesthetic rule that green is real and grue is fake, then inductive reasoning itself falls down like a row of dominoes, and science with it. But that anticipates the arguments from reason later in the chapter. At any rate, beauty can’t really translate into molecules and energy. If molecules and energy are all that there is, then beauty isn’t real. If beauty is real, then scientific materialism can’t account for the universe.

Our powers to exercise free will and to perceive beauty and moral truth are aspects of consciousness, the life of the mind, the thought realm that each of us inhabits 24/7, and that's another thing we know to be real that scientific materialism can’t account for. We see everything else through the lens of this. Mind is more fundamental than matter in our experience, because mind is what we are, while matter is a mere deduction from patterns observed. But if we were merely evolved from particles, why should there be subjective experience? How could there be? How would it arise? No mere complexity of apparatus could necessitate that. Computers are no more conscious than abacuses, or forks. We know that consciousness exists because we experience it internally. But for that, it’s not clear how we would ever guess, from external evidence, that it’s there. Consciousness is a completely different kind of phenomenon than anything that can be described by physics, or chemistry, or by the kind of biology that stays closely tied to chemistry and physics. You would never learn about consciousness by studying how DNA replicates and how proteins fold, or even how neurons fire. It is as gratuitous a feature of reality as a mural painted on a brick wall, and to explain it from the microphysical properties of the natural world is as vain as trying to explain why the mural on a brick wall features birds and sunflowers and smiling children, from the crystallography of the bricks or the chemical composition of the mortar.

Followers of scientific materialism generally don’t claim that consciousness has been explained. Rather, they have faith that it will be. Science keeps explaining more and more things. Someday, they are sure, it will explain consciousness too, and maybe even produce it. And so science keeps chasing the chimera of "artificial intelligence," trying to make computers or robots with thoughts and faculties and experiences like those of people. But confidently to expect science to explain the human mind is to misread the trends. Science has gone on explaining more and more about the natural world, including human bodies in their merely physical aspect. The way we understand weather, plant growth. the properties of materials, electricity, stars and astronomy, health and sickness, rocks, fire, fungi, eyes, kidneys, and so forth has been profoundly changed by science. But science has contributed essentially nothing to our understanding of how we ought to live, what makes us happy, what we find beautiful, or how we think. When people want to know these things, they turn to cultural, not scientific sources, to proverbs or scriptures or poets, to religion and literature, not to science. 

Psychology is the exception that proves the rule, for it has sometimes had a real impact on people’s understandings of the human mind, but its status as a science is very questionable. Its most influential figure, Sigmund Freud, had a powerful impact on literature, but is now pretty thoroughly discredited as a scientist. The great psychologists have found niches in intellectual history resembling those of philosophers, not those of pure scientists. Psychology has never generated an accumulating body of lawlike generalizations, validated by experiments and observations, and useful for predictions that become increasingly accurate and exact, like physics and chemistry. Psychology has been more like religion, with psychologists as its priesthood and the psychiatric couch a secularized confessional, with believers and unbelievers, participants and nonparticipants. It seems to have helped quite a few people, though far fewer than Christianity has, even as psychological schools have gone in and out of fashion. And none of the successes that psychology has had have anything to do with reducing the mind to a microphysical basis. Psychologists learn about people as priests do in the confessional, just by talking to them. A few mental problems do have neurological explanations. But if a person is mentally healthy and normal, materialistic science has no idea why. 

Scientific materialists sometimes mock arguments for God or a supernatural soul from the scientific inexplicability of a phenomenon as a “God in the gaps” or “ghost in the machine” argument. Since science has often explained things that that were previously attributed to supernatural causes, it's folly, so they suggest, to argue from gaps in science’s explanatory power to the existence of supernatural entities. Yet as I mentioned in chapter 2, it’s very doubtful whether science actually has any track record of embarrassing Christianity, as distinct from paganism and popular superstition, by explaining away phenomena that had been presumed supernatural. And when it comes to the human mind, any such boasting on the part of science would be utterly delusional. Scientists have thought for generations that the human mind must be explicable on materialistic principles, yet their success in producing such materialistic explanations has been about as great as that of medieval alchemists trying to turn base metals into gold by mingling them with fire. Christians who have clung to the belief that the human mind is a supernatural affair, far from being embarrassed, can congratulate themselves that their old dogma not only remains completely unrefuted, but has spared them from falling for foolish fads and fancies such as Freudianism.

Scientific materialists are so habituated to letting assumed future discoveries complete their portrait of the omniscience of science, that it never seems to occur to them that the nearly complete failure of science to render the human mind explicable or predictable ought to disturb their complacent belief in scientific materialism. Again and again, they play a game of “heads I win, tails, we flip again.” If a materialistic explanation succeeds, that vindicates faith in science. If it fails, that only discredits that particular scientific theory. It does not discredit science, or limit the scope of its explanatory prerogatives, in the least. They never let scientific materialism itself be put on trial. We just have to keep waiting for a better scientific explanation to come along. No frank seeker after truth should accept these rigged rules of the game. Science has achieved wonders in explaining the workings of physical nature, but it has had negligible success in explaining the wonderful powers of the normal, healthy human mind, in spite of lots of trying. It's reasonable to start drawing the conclusion that the human mind is not a part of physical nature, though it can penetrate and colonize physical nature in a limited way through the brain and the body. Man is, as C.S. Lewis said, "amphibian," inhabiting two elements, mind and matter. He is a supernatural soul in a material body. And again, that conclusion is a rejection of the scientific materialist worldview.

But the most fatal flaw in scientific materialism is that, after starting from rationalism, it cannot but end by attacking reason. If carried to its logical limits, it must rob human reason of its warrant for being believed, thereby pulling the rug out from under science and refuting itself. Scientific materialism is like the woodcutter who cuts off the branch that he is sitting on.

Let's start with a version of the argument from reason in the peculiar epidemiological idiom of this book, building on the kind of Bayesian rationality described in earlier chapters. 

Let's say you start by framing a Scientific Materialist Conjecture, as follows:

SCIENTIFIC MATERIALIST CONJECTURE (A): All things that exist consist of matter and energy and are governed by the laws of physics. 

Let's say you initially attach a 50% probability to the Scientific Materialist Conjecture being true. Because there is a large body of well-attested knowledge in physics, you can, in a sense, make a lot of predictions from the Scientific Materialist Conjecture that could be tested. But there's a trick here, since the Scientific Materialist Conjecture doesn't include specific laws of physics. So it's not necessarily damaged if an experiment yields an unexpected result. On the other hand, alternative worldviews may, as Christianity does, accept the laws of physics in general, while denying that they cover all that exists and that they're perfectly reliable and exceptionless. In everyday situations, therefore, a Christian's predictions will probably be just the same as those that would flow from the Scientific Materialist Conjecture, and the fulfillment of such predictions would have no impact on relative Bayesian confidence in either rival worldview. 

But let's suppose all these difficulties are surmounted somehow. The seeker is able repeatedly to frame P(B|A) and P(B|~A), where B is some event and A is the Scientific Materialist Conjecture, and keeps finding that P(B|A)>P(B|~A), and that B occurs. He therefore attaches ever-increasing probability to the Scientific Materialist Conjecture, until he is nearly certain that it is true, because it describes reality as he and others have experienced it. I hope at this point any scientific materialist readers are nodding complacently with approval, because I'm trying to represent fairly how I think a lot of scientific materialist convictions come about, and even more, how scientific materialists think they do and ought to come about. This is scientific materialism as realism, as a conclusion drawn rationally from experience. I've described this before, in chapter 3, where I set up a kind of race between the improbability of miracles and the improbability of the kind of spontaneous, motiveless conspiracy that would have been needed to fake the Resurrection. There, I conceded that the inductive case for the reliability of natural laws is very strong, and scientific materialism affirms and generalizes from that.

But wait a minute! What about Bayes' Law itself? What is Bayes' Law? Does the Scientific Materialist Conjecture apply to it, too? Does Bayes' Law consist of matter and energy? Is it governed by the laws of physics? The very suggestion seems absurd and inconceivable. 

If the Scientific Materialist Conjecture is true, it would seem to follow that Bayes' Law, and numbers, aren't real, since they lack the quality, which is asserted to be characteristic of all things that exist, of consisting of matter and energy. But if Bayes' Law does not exist, how could we use it on our reasoning? And how could we be justified in adopting beliefs that come by applying a nonexistent law? And so the reasoning process by which our Bayesian scientific materialist arrived at his scientific materialist convictions is discredited by the ontological abolition of entities required by the reasoning process. The more scientific materialism is proved, the more it is disproved.

The argument from reason against scientific materialism doesn't specially arise from the peculiar epistemological idiom of this book. It's much more general than that. Any model of reasoning you can frame can easily be recruited to refute scientific materialism by confessing that it assumes non-material entities as part of the reasoning process. For scientific materialists, there's nowhere to run, nowhere to hide from the argument from reason. There are many forms of the argument from reason, all basically compatible and mutually reinforcing. 

I like to start with the cleanest of them all: the argument from numbers.

What is the number two? How does it fit into things? Or what about a fact like 2+2=4? Clearly it would make no sense to ask "Where is the number two right now?" or "When did two plus two make four?" It would be even sillier to ask what the number two is made of, or ask how many joules of energy are required to transform two and two into four. Two has no time, no place, and no material substance. If the stars burn out and the galaxies disperse into dust, two and two will go on making four forever. Common sense takes numbers for granted, and science, far from weaning itself of the need for numbers, is particularly adept at applying advanced mathematics to all sorts of problems. But what is the metaphysical status of all this math? Is it real? Surely. It's not fictional or a matter of opinion. Old Plato made his students study math for years before he would teach them philosophy, for it helped them grasp his theory of eternal forms, and math stands ready, whenever we stop to think about it, to turn us into Platonists again. There could be math without nature, numbers relating abstractly in the void, but there could be no nature without math, for all its workings are governed by math. We can neither deny numbers not integrate them into a scientific worldview. We must admit them as immaterial entities, which invalidates the materialistic picture of the universe at a stroke.

But there's more, for it turns out that any application of math to the world requires that ideas be real too. To see why, consider the phrase "two cats." The cats must be different, else they would not be two, yet they must be the same, else they would not be cats. They may differ in accidental features like fur color or size, but that's inessential. Even if they have exactly the same features, so that they were indistinguishable, they are still two cats, comprising different matter, and occupying different positions in space. But they share catness, which Plato would expand on by saying that they both participate in the idea, the eternal form, of catness. That's why we can count them. One, two. One cat, two cat. One instance of catness, two instances of catness. If we couldn't recognize them as two instances of some idea, we couldn't count them. There would be no continuity between one cat and the next to justify the continuation of a number series. So we need ideas like catness as a prerequisite for the scientific project of measuring and quantifying natural phenomena. 

But where does the idea or category of catness reside? What is it made of? That's not quite as obviously nonsensical as asking for the chemical composition of the number two, since cats at least have a largely common physical constitution. But it's still pretty obvious that the instances of catness, not the idea of catness, are comprised of matter that has a chemical description. And a picture or a poem might also participate in the idea of catness in its own way, without its material substance bearing any chemical resemblance to the innards of cats. 

Plato would locate catness in the realm of eternal forms, which is a better story than modern philosophers, who are addicted to trying to make the world safe for scientific materialism, can offer. But even modern philosophers recognize "the problem of reference." If I am thinking about cats, what does that mean? What is this relation of "aboutness" between me and my thoughts, on the one hand, and one or many really existing cats, on the other? It's another thing which we can neither deny the reality of, nor fit into a scientific materialist picture of the world. And as all reasoning about the world is full of reference, to believe in reference is a prerequisite for reasoning. But does the relation of aboutness that connects my thoughts to matter and energy itself consist of matter and energy? Is it governed by the laws of physics? How could that be? If we can't conceive of a physical basis for reference, then scientific materialism robs us of the right to refer to or describe the world by means of propositions. But statements like the Scientific Materialist Conjecture are propositions that purport to describe the world. And so, again, it destroys itself.

The phenomenon of reference, which connects our words and thoughts to things in the physical world by a relation that is clearly real but has nothing to do with physical contact, sets the human mind apart, at least as far as our experience is concerned. Other things refer only via the human mind. Thus, a physical book, consisting of ink and paper, refers to things outside itself, and has aboutness, but only through human readers. If a copy of Moby Dick somehow existed 30 million years ago, before the English language or the human race, it would mean nothing. The ink and paper itself has no power to refer, to mean anything. It only has meaning through human minds in which it inspires thoughts. In the same way, nothing that happens in a computer means or refers to anything, except through human minds that supply inputs and interpret outputs. But the real marvel isn't just that human thoughts have this unique property of aboutness, this strange power of reference, but that they can refer to reality so accurately, perceiving so much of the grand pattern of the physical universe.

Suppose you went into an orchard, and after walking around its roads and paths for a while and getting to know its features, your eye is caught by something odd on the bottom of a leaf. On closer inspection, it turns out that the veins and markings on the bottom of the leaf form a perfectly accurate and minutely detailed map of the orchard itself. To find the human mind in the midst of nature and yet possessing the power to understand it has the same sort of oddity about it. The irony is that even as science supplies the materials for a worldview that denies human exceptionalism, it exemplifies human exceptionalism in a uniquely high degree. It's not just that no other species practices science, but that the ability to achieve prodigious feats of scientific understanding sets man wildly apart from the regular order of nature in which the traits of creatures mostly seem to be explained by the need to survive in some ecological niche. 

I'm indebted to C.S. Lewis's book Miracles for first understanding the decisive force of the Argument from Reason. The form the argument takes in that book starts with distinguishing two senses of the word "because." On the one hand, "because" signifies physical causation, e.g.,  one billiard ball moved because another billiard ball stuck it. On the other hand, "because" signifies rational inference, e.g., it must have rained because the streets are wet. Lewis points out that we always treat physical causation of belief-- for example, I only thought something because I was tired or drunk-- as disproving its trustworthiness. Only rational inference gives us a pathway to true beliefs, and when physical causation interferes with the workings of the mind, competing with rational inference as a cause of belief, the mind becomes unreliable. If you believe in reason as a supernatural faculty, you can still admit that its interface with the brain can be a source of interference and damage. But if human beings were reducible to a material basis, then everything we think would come from the equivalent of being tired or drunk. All our beliefs could be explained away as merely a function of biology, of evolved instincts or chemical accidents, and we would have no reason to trust any of them. I can't do justice to Lewis's argument here, but if you haven't read the book, it would be well worth reading it to help drive these points home. The philosopher Victor Reppert (1953-), in his 2003 book C.S. Lewis's Dangerous Idea: In Defense of the Argument from Reason refines C.S. Lewis's argument and defends it against a variety of criticisms.

Somewhat separately, there is an argument from reason specifically against human evolution, articulated, among other places, in Alvin Plantinga's (born 1932) 2011 book Where the Conflict Really Lies: Science, Religion and Naturalism. It focuses on the implications of claims about the evolutionary origins of the human race for the reliability of human reason. If human beings evolved, merely evolved, most recently from apes, and ultimately from microbes, then all our features, including our powers of reasoning, ought to be explained as adaptations for survival and reproduction, our own and that of our selfish genes, in some ancestral environment. But in no environment of evolutionary adaptation that natural history attests could the latent capacity for true inference in advanced realms of math and science plausibly confer an evolutionary advantage on human beings. Why should we have such powers of reasoning then? If we know by introspection that we have the feeling of making true inferences in such matters, can we trust such feelings? Why? 

To a limited extent, an ability to reason accurately may be adaptively advantageous, but it's not hard to imagine cases where false convictions would be adaptively advantageous. A man in sexual pursuit of a woman will probably benefit by convincing her that he will love her forever, even if he's more likely to seduce and abandon her. He'll be more persuasive if he genuinely thinks that he will. So delusions about his own likely fidelity could be adaptive, and in fact, such opportunistic beliefs in sexual affairs do seem to come naturally to men, and we see this drama play out all the time. For the same reason, women seem to have a propensity for making, with great conviction, promises of lifelong, faithful love that they often won't keep, and in general, the whole field of romantic love is littered with broken promises that bear witness to instincts driving us to convictions other than the truth. It's all very consistent with C.S. Lewis's argument that when physical causation intrudes in our thoughts, they become unreliable. If our powers of scientific reasoning were merely evolved, why should we trust our scientific conclusions any more than the oft-broken promises of lovers?

Moreover, most biological features have a cost, and whether they're adaptive or not depends not only on whether they're useful, but on whether they're worth the cost. That's why we shouldn't be surprised that human beings can't fly, even though flying would obviously be very useful. It's not feasible to fly with a body plan remotely like ours, but there are other advantages, such as strength and proficiency in walking and grabbing, that make our body plan adaptive even at the cost of flightlessness. If having a latent capacity for scientific reasoning is at all costly, then not only should natural selection not have favored it in our ancestral environment, it should have selected against it, breeding it out of the population by killing off the people whose genes wasted resources on maintaining a latent capacity for science. 

Is latent scientific ability biologically costly? We can't say, because we have no idea how a capacity for scientific investigation arises from the molecular matrix of the kind, and we never will, because, as we have glimpsed already, scientific reasoning depends on communion with a transphysical realm of Platonic ideas and is an essentially supernatural faculty, on which scrutiny of neurons will never shed any real light. But never mind that for now. Let's suppose for the sake of argument that latent scientific capacity is a merely biological phenomenon, and is at least somewhat costly to the organism that maintains it. We can't see how it could possibly have been adaptive in our ancestral environment, but we seem to have it, so maybe either it was adaptive in some inscrutable way, or maybe it simply arose by accident and selective pressures weren't strong enough to wipe it out. On the other hand, what if it were adaptive, not so much to have powers of scientific discovery, as to have a propensity for merely for self-confident scientific belief? We might be wired, not to discover truth, but merely to think we're right. How would we know? 

And even if we do manage to come up with arguments for the trustworthiness of reason that we find convincing, is that because they're true, or just because we're evolved to think they're convincing? In general, if ever the basic reliability of reason is questioned, there's no escaping a treadmill of infinite self-doubt. If the reliability of reason is doubtful, then I might try to frame arguments in its defense. That's difficult. But even if I succeed, and develop arguments in defense of reason that sound convincing, is that because they're true and sound arguments, or because part of the inherent fallibility of my reason consists of being unable to discern the falsity of certain arguments in defense of my reason? But we can't avoid stepping into the treadmill if the first step in our ontologies is to deny the fundamental and primary reality of anything but the entities studied by physics. If I have to derive mind from matter, I can't be sure ex ante that mind is reliable, and if I don't start with faith in reason, then I can't establish the reliability of reason through any reasoning.

The irony, then, is that Darwinian evolution, if true, is evidence against itself, because the humanity it describes would have been unable to discover the truth of Darwinian evolution. If Darwinian evolution is true, then it's most likely false, because the humanity it describes would be more likely to have a propensity merely for overconfident mythmaking than for a latent capacity, quite useless in the ancestral environment, for genuine discernment and discovery in advanced and subtle topics such as biological natural history. More generally, if we trust scientific materialism, we must ultimately come to doubt reason, because efforts to frame scientific materialist accounts of the origin and nature of human reason inevitably undermine its trustworthiness. If, on the other hand, we insist on the authority of reason, we must recognize it as a reality independent of and superior to mere physics, thus rejecting scientific materialism.

I don't think this bias of scientific materialism against reason is a mere abstraction. I see in the history of the human intellect in recent centuries a tendency to turn against reason when the scientific materialist worldview is in the ascendant. The most striking case of this is the Soviet Union, where scientific materialism was integral to the official philosophy of the regime, and where reasoning minds and free thought were comprehensively subjugated and muzzled. Marxism tends to reduce reasoning to economic interest: one argues in favor of property rights because one is a bourgeois. It's not a bad theory if you've rejected a supernatural origin of human reason and it has to come from somewhere. But the consequence is that there's little motive for tolerating argumentation from the other side if it's only class warfare by other means, and so it became unsafe to speak your mind in Soviet Russia. In my lifetime, I feel as if a similar, though less severe, turn against reason has taken place as irreligion has become more widespread. As scientific materialism and the theory of evolution rob human reason of the supernatural authority that it ultimately derived from the Christian doctrine that man was made in the image of God, reason tends to be reductionistically explained as the expression of class interest. You say that because you're a man, or because you're white, or a member of some other privileged category. There's no need to address your arguments. And so, on university campuses and in many large organizations, it becomes dangerous for dissenters to speak their minds, since dissenting arguments seem like mere treason against the arc of history, mere reactionary class warfare by other means.

Be that as it may, enough has been said to establish the falsity of scientific materialism. It fails because there are too many things evidently real which are incompatible with it. There is free will. There is moral right and wrong. There is objective beauty. There is consciousness. There are numbers. There are ideas. There is the mysterious phenomenon of reference, linking thoughts in the mind with things in the world by obviously non-physical means. And there is the human power, long largely latent, to form an amazingly rich and complex map of reality. The coherence of scientific materialism as a worldview depends on fitting everything into a framework founded on physics. But many aspects of reality refuse to fit into that cage. Reality is just more complicated than that. Meanwhile, the universe has a beginning, and scientific inquiry cannot reach behind it to see why it began. It needs a cause other than itself, especially since the original conditions of the Big Bang and the laws of physics are fine tuned to support life. The nature of the scientific enterprise sets limits on what it could potentially explain, and much of reality lies outside those limits, so if we want to understand the universe, we need a different worldview that is not so dependent on science for tying everything together.

Christianity is the opposite of scientific materialism in two major ways that make it, prima facie, a promising candidate for succeeding where scientific materialism fails. First, it makes mind more fundamental than matter. Instead of matter coming first and mind evolving from it, a mind, namely the mind of God, came first. All the special features of minds, reasoning and ideas and free will and so forth, can therefore be accepted as we find them and don't need to be given material explanations. Philosophy of mind is still a difficult subject, but at least it need not be burdened with the impossible quest of reducing the mind to a byproduct of physics and chemistry.

Second, Christianity tends to multiply, rather than reducing, the variety of entities that are acknowledged to be real. Where scientific materialism contradicts common sense by denying free will, Christianity challenges common sense by affirming the existence of angels and devils and miracles. There are things like magic and pagan gods that most pre-Christian people have believed in, but science and Christianity join in rejecting. Yet even here, Christianity does not have official doctrines that deny the existence of magic or pagan gods. Long before the Enlightenment, there were Christian leaders who thought that magic and pagan gods were simply non-existent, but plenty of other Christians thought they might be real, and Christianity didn't rule one way or the other. What Christianity insisted was that Christians shouldn't worship pagan gods or practice magic, nor need they fear them, for the power of Christ was superior. But they might be real in some way. Popular belief in fairies persisted in northern European countries for centuries after they were converted to Christianity. Often, Christians believed in witches, in women who sold their souls to the devil in exchange for magical powers which they used for evil, and occasionally, alas, they killed people on charges of witchcraft. As science has purged people's minds of beliefs in witches and magic and pagan gods and fairies, Christianity has rarely resisted, and if anything, has generally approved and/or helped, yet it's revealing that these subtractions from the inventory of what is held to be real weren't really spearheaded by Christianity. Christianity isn't generally in the business of denying the existence of things. It is the champion of a richer reality, with more things in it.

A disclaimer is needed here, because I'm not exactly going to say, as the flow of the argument might lead people to expect, that Christianity achieves the grand coherence of truth that scientific materialism fails to achieve. Christianity is not a "theory of everything" in the way that scientific materialism aspires to be. It is more like a roadmap to the kingdom of heaven. Compared to the know-it-all propensities of scientific materialism, Christianity is willing to let much of reality be somewhat mysterious. A roadmap doesn't need to tell you everything about a country. It might do well to include a lot of wrong roads, to help you get back on track if you make a wrong turn, and to describe landmarks and landscapes, to help you identify where you are by looking around. But it should omit a lot of distracting details to help you focus on finding the right roads. To a certain extent, Christians are kept by God on a need-to-know basis. I'm not sure that there's anything Christianity forbids men to study, though a certain kind of curiosity about devils or sexual perversions could be unhealthy, but there are plenty of topics about which the Church offers no guidance, leaving it to individuals to discover what they can, if they wish.

What I think Christianity does is to offer a coherent system of enough beliefs to live by. A well instructed Christian knows what he must believe, what he must not believe, and what he may believe or disbelieve as he sees fit. He can trust Christianity to have audited the mandatory beliefs for coherence and consistency, even if he can't always see why they're consistent. He can feel reasonably confident that the optional beliefs won't contradict the mandatory beliefs, though of course some of them might contradict each other. He'll fall into inconsistency if he adopts the forbidden beliefs while still trying to be Christian, so he should avoid that. In practice, his mind will be full of optional beliefs that Christianity doesn't specially endorse, from his own address, to how to make fried chicken, to the heliocentric theory of the solar system. It would be very impractical to try to have no beliefs except what the Church teaches. But it's not disastrous, in the eternal perspective, if he gets some of these wrong. It might be disastrous in a natural sense. If he misidentifies a mushroom, or the repair needed by an aircraft, a false belief on a non-doctrinal question may kill him, but it won't damn him. Nor is belief enough: salvation depends on attitudes and actions as much as on beliefs. But Christianity gives him enough knowledge to keep him on the right road. A man who confidently believes all that Christianity teaches, confidently denies all that it condemns, and is tentative about everything else, is well equipped to direct his efforts and deal with the chances and changes of life in a way that makes his life worth living and his soul capable of salvation, even if he never knows about the Jurassic period or the law of conservation of angular momentum, and can't solve a differential equation.

And so a lot of the questions that I raised in arguing against scientific materialism will not be answered in the course of my explanation and defense of Christianity. In particular, my study of human reasoning has led me to adopt, at least as a placeholder, a kind of Platonic idealism, whereby I affirm the independent reality of ideas. That raises a lot of questions about what ideas are and how they relate to their instantiations in the world. But I won't try to answer those questions, because Christianity doesn't. It avoids some of the critiques by which scientific materialism comes to grief by not making such strong claims, at the cost of leaving the mind with large regions of unknowns. But it gives us enough to live by.

Now, as I mentioned before, it's difficult to organize a book, because the text has to flow from left to right, page after page, beginning to end, yet the argument may be naturally more branching than that. This is a Choose Your Own Adventure moment. The next four chapters represent a kind of detour, or digression. At one level, the chapter that most naturally follows from this one is chapter 14. That's where I embark on a sweeping exposition of the Christian worldview, the great alternative to the failed worldview of scientific materialism. And you may understand chapter 14 best if you skip the chapters in between, so that this chapter and the argument leading up to it are fresh in your memory. Another reasonable Choose Your Own Adventure option is to proceed to chapter 10, which explains the rough concordance of Genesis 1 with scientific natural history, and then skip to chapter 14. Or again, you might skip to chapter 14, then back to chapter 11, which deals with ethics and the Golden Rule, and then skip back to chapter 15 to read about the ethics of Jesus. Anytime you skip in a book, there's a risk that you'll miss something that is necessary to make subsequent material understandable. I won't guarantee that that's not the case here, and that all these Choose Your Own Adventure options will strictly “work,” in the sense that there will be no unintelligible references, no dependencies. But I think you should do will right if you choose to go that way.

The reason I've organized it the way I have is that I think a lot of modern readers won't be ready to take the Christian faith seriously because they think either that (a) Christianity is discredited by its indelible connection with a false view of natural history, or (b) Christianity is discredited by its primitive, joyless, irrational, and outdated scruples about sex, and so they won't be able to muster much interest in what it has to say about the larger themes of Creation, Fall, and Redemption. So the next four chapters address what might be called the “hot topics,” that is, topics about which historic Christian teachings happen to be especially controversial in contemporary Western civilization, of Genesis 1 and creationism, and of chastity and sexual ethics. Concerning the first, I show why the text of Genesis 1 clearly implies a “day-age” interpretation, after which an effort to fit the “days” of Genesis 1 with scientific natural history works surprisingly well. Concerning the second, I show why combining the insights of sociobiology about the natures of the sexes and their asymmetric desires, needs and jealousies, combined with the strangely commonsensical yet also quixotic principle that we should do unto others as we would have them do unto us in their place, leads directly to the full panoply of Christian sexual rules, which, far from being irrational taboos, are precisely the wisely discerned secret of rationally managing sexuality to make us good and happy. That should be enough to go by if you want to skip straight to chapter 14. If you need to understand these points better, turn the page.