But what is the argument? In short, Plantinga claims that humans could never have true beliefs about anything without God’s intervention. Natural selection, he says, promoted only our ancestors’ ability to leave copies of our genes through differential survival and reproduction. It doesn’t give a hoot about whether our beliefs, such as they are, are true. Considering our cognitive faculties, for instance, Plantinga says:
What evolution underwrites is only (at most) that our behavior is reasonably adaptive to the circumstances in which our ancestors found themselves; hence it does not guarantee mostly true or verisimilitudinous beliefs. Our beliefs might be mostly true or verisimilitudinous . . . but there is no particular reason to think they would be: natural selection is not interested in truth, but in appropriate behavior.
The most important “truth” that Plantinga thinks humans perceive is, of course, the existence of the Christian God and Jesus, and the salvation that can be attained only by accepting these deities. But he also claims that without God we wouldn’t be able to perceive scientific truths, including those involving biology and physics:
God created both us and our world in such a way that there is a certain fit or match between the world and our cognitive faculties. The medievals had a phrase for it: adequatio intellectus ad rem (the adequation of the intellect to reality). The basic idea, here, is simply that there is a match between our cognitive or intellectual faculties and reality, thought of as including whatever exists, a match that enables us to know something, indeed a great deal, about the world—and also about ourselves and God himself.
Elsewhere he writes, “This capacity for knowledge of God is part of our original cognitive equipment, part of the fundamental epistemic establishment with which we have been created.”
Plantinga argues that the naturalistic process of evolution is incapable of producing a brain that apprehends the truth of evolution, much less of any other idea. He therefore sees a conundrum: “What I’ll argue is that naturalism is incompatible with evolution, in the sense that one can’t rationally accept them both.” Plantinga himself waffles about whether he accepts evolution, for he seems to have a fondness for intelligent design.
What we have here, then, is the claim that a critical part of human cognition can’t be explained by naturalistic evolution. Plantinga argues that our real truth detector is a “sensus divinitatis” (“sense of divinity”) installed in humans—and no other species—by God, as part of our creation in his image. (This idea derives from John Calvin, a figure much admired by Plantinga.) This is clearly a “god of the gaps” argument, one that Plantinga sees as forging a harmony between science and religion:
There is superficial conflict but deep concord between science and theistic religion, but superficial concord and deep conflict between science and naturalism.
I won’t belabor the obvious objection that even if we had such a divinely installed sensus, it’s not evidence for Plantinga’s Christian God as opposed to any other god. While he sees the Christian divinity as a “basic belief,” something as obvious as believing that you ate breakfast this morning, there’s no reason why other deities could also have given us a sensus divinitatis—in fact, the firm belief of Muslims in Allah argues that the whole notion of a Christian sensus is insupportable.
But let’s leave this theological ground and ask ourselves two questions: Do humans really have consistently accurate beliefs about the world? And, whether they do or not, can the truthfulness of some beliefs be explained by evolution and neuroscience?
The answer to the first question is yes: we generally see the external world accurately, and often have a good take on our fellow humans as well. But, importantly, we’re also prone to all kinds of false beliefs. Steven Pinker lists a few:
Members of our species commonly believe, among other things, that objects are naturally at rest unless pushed, that a severed tetherball will fly off in a spiral trajectory, that a bright young activist is more likely to be a feminist bankteller than a bankteller, that they themselves are above average in every desirable trait, that they saw the Kennedy assassination on live television, that fortune and misfortune are caused by the intentions of bribable gods and spirits, and that powdered rhinoceros horn is an effective treatment for erectile dysfunction. The idea that our minds are designed for truth does not sit well with such facts.
And we’re particularly prone to self-deception. Psychological studies confirm that many of us tend to think we’re smarter, better-looking, and more popular than we really are (for many examples, see Robert Trivers’s book The Folly of Fools: The Logic of Deceit and Self-Deception in Human Life). Such consistent self-overrating may in fact have an evolutionary basis, for it helps us get our way when dealing with other people. Nobody is more convincing than a liar who believes his own lies, so an inflated self-presentation in our ancestors may have gained them leverage with others—and a reproductive advantage.
Now add to our distorted self-image the prevalence of delusions and errors like climate-change denialism, as well as belief in UFOs, alien abduction, astrology, ESP, and so on (I’d add for believers, “all religions with the possible exception of the ‘right one’—yours”), and we see that our species is vulnerable to all manner of false beliefs. We’re deceived by optical illusions too, like Ted Adelson’s stunning “checker-shadow illusion,” in which a light square falling in the shaded part of a shadowed checkerboard is mistakenly perceived as being much lighter than a square lying outside the shadow—even though both are exactly the same shade. That too is probably a by-product of natural selection, which is likely to have given our visual system a way to detect and compensate for the effect of shadows on the color and hue of objects.
The skeptic and science writer Michael Shermer has written extensively about why people believe untrue things. The many reasons include confirmation bias (a preference for believing what we find comforting), ignorance of how probability works, resistance to change, and a penchant for indoctrination. Many of these tendencies could have been useful in the environment of our ancestors, an environment in which we no longer live. After all, our ancestors didn’t encounter checkerboards in partial shadow, and didn’t know probability theory.
To sum up, our brains are fairly reliable but hardly perfect organs for detecting truths. And many of these imperfections, pervasive in people of all faiths, can be plausibly understood as products of natural selection. So much for the argument that God gave us a reliable truth-detecting apparatus. In fact, if Plantinga’s own sensus divinitatis were working properly, he wouldn’t have accepted the scientifically discredited notion of intelligent design!
Of course, Plantinga has an answer for why there are so many atheists, Hindus, Jews, Muslims, and pre-Christian believers, like the Aztecs and ancient Egyptians, who were somehow unable to form true belief in the Christian God. The answer is that in those individuals the sensus divinitatis is or was “broken,” dismantled by the effects of sin. Curiously, Plantinga argues that your broken sensus need not stem from your own sin:
Were it not for sin and its effects, God’s presence and glory would be as obvious and uncontroversial to us all as the presence of other minds, physical objects and the past. Like any cognitive process, however, the sensus divinitatis can malfunction; as a result of sin, it has been damaged. . . . It is no part of the model to say that damage to the sensus divinitatis on the part of a person is due to sin on the part of the same person. Such damage is like other disease and handicaps: due ultimately to the ravages of sin, but not necessarily sin on the part of the person with the disease.
Here we have an untestable explanation for an insupportable thesis. But we needn’t mire ourselves in such arguments. Rather, let’s address the real situation: humans are good at detecting some truths and poor at detecting others. Some of our beliefs are rational and supported by evidence, while others are not. Can we plausibly explain this using naturalism alone, including evolution?
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p; Indeed we can. The first thing to realize is that humans aren’t born with explicit beliefs; we’re born with a brain molded by natural selection to form beliefs when the brain gets input from the environment. Some of those beliefs involve learning from parents and peers, others from empirical observation. It’s easy to imagine that in our millions of years of living in small bands of hunter-gatherers, we, like many vertebrates, evolved a tendency to absorb what our parents taught us (surely one reason why religion persists). Your chances of surviving are a lot better if you benefit from the experience of adults rather than having to learn everything for yourself. We might have learned, for instance, to avoid large mammals that look like cats but not those that look like antelopes: those who didn’t learn this distinction didn’t become our ancestors. Other things, like which of our peers we can trust and which we should avoid, could have been figured out on our own. Still other rational tendencies—not beliefs, really, but adaptive behaviors—could have been directly produced by natural selection. Preference for kin and wariness toward strangers have obvious adaptive consequences, and would assume the status of “beliefs” at a certain age (“I believe that we should be wary of people we don’t know”).
While our view of the world is filtered through our senses, evolution has, by and large, molded those senses to perceive the world accurately, for there’s a severe penalty to be paid for seeing things wrongly. That holds not only for the external environment, but also for the character of others. Without accurate perceptions, we couldn’t find food, avoid predators and other dangers, or form harmonious social groups. And following those perceptions is indeed the pursuit of “true beliefs”: beliefs based on evidence. Natural selection doesn’t mold true beliefs; it molds the sensory and neural apparatus that, in general, promotes the formation of true beliefs.
But of course we’ve seen that not all of our beliefs are true. That’s because while natural selection has given us a pretty good truth-detecting apparatus, that apparatus can also be fooled, as in the checker-shadow illusion. And religion could be one of the false beliefs that piggybacks on evolution. The anthropologist Pascal Boyer, for instance, proposes that religion began with the inborn and adaptive tendency of our ancestors to attribute puzzling events to conscious agents. If you hear a rustle in the bushes, you’re more likely to survive (or get food) if you believe it came from another animal than from a gust of wind. These beliefs about conscious agents in nature can easily be transferred to things like lightning and earthquakes. Because our ancestors lacked naturalistic explanations for such things, conjectures about supernatural humanlike beings or spirits might follow. Studies of child development suggest that religious beliefs are not inborn—that we have no “God genes.” Rather, as Boyer and others suggest, our evolved cognitive apparatus gives us a propensity to accept religious propositions such as God, the afterlife, and the soul, and those specific beliefs are learned.
It’s no surprise that children in southern India come to believe in multiple deities, while those in Alabama in the divinity of Jesus—observations that directly contradict Plantinga’s view that our sensus divinitatis was vouchsafed by the Christian God. Rather, religion is likely to be what Stephen Jay Gould and Elisabeth Vrba called an “exaptation”: a feature that, while sometimes useful, was not itself the object of natural selection, but piggybacked on features that evolved for other reasons.
All in all, there’s no reason to see science as incapable of explaining why our beliefs about the world are often true. It also has plausible explanations for beliefs that are false, explanations far more credible than Plantinga’s view that our failure to detect truth indicates a sensus divinitatis broken by sin.
A related argument for God is that the human brain has abilities far beyond anything that would be needed by our African ancestors. We can build skyscrapers, fly to the Moon, cook elaborate dishes, and make (and solve) Sudoku puzzles. Yet such abilities could not possibly have been useful during nearly all of the period when our brain evolved. How then do we explain them? To some theologians, the answer is God.
As we learned earlier, the first one to raise this problem was the biologist Alfred Russel Wallace. Although a tireless and selfless promoter of evolution by natural selection (he called his book on the topic Darwinism), Wallace could not see how selection could produce the multifarious abilities of the human brain. Here’s his argument, tinged with the paternalism of the nineteenth-century Englishman:
We see, then, that whether we compare the savage with the higher developments of man, or with the brutes around him, we are alike driven to the conclusion that in his large and well-developed brain he possesses an organ quite disproportionate to his actual requirements—an organ that seems prepared in advance, only to be fully utilized as he progresses in civilization. A brain slightly larger than that of the gorilla would, according to the evidence before us, fully have sufficed for the limited mental development of the savage; and we must therefore admit, that the large brain he actually possesses could never have been solely developed by any of those laws of evolution, whose essence is, that they lead to a degree of organization exactly proportionate to the wants of each species, never beyond those wants—that no preparation can be made for the future development of the race—that one part of the body can never increase in size or complexity, except in strict co-ordination to the pressing wants of the whole.
In short, the brain seems to defy the idea that natural selection can’t prepare organisms for environments they’ve never encountered. As a result, Wallace concluded that evolution could explain everything but a single organ in a single species.
We’ll see in a moment that science has long since disposed of Wallace’s teleology, but the idea of the overengineered human brain is still with us. It is in fact touted by Plantinga, who argues that because evolution can’t explain our ability to do complex mathematics and physics, those aptitudes also come from God:
These abilities far surpass what is required for reproductive fitness now, and even further beyond what would have been required for reproductive fitness back there on the plains of Serengeti. That sort of ability and interest would have been of scant adaptive use in the Pleistocene. As a matter of fact, it would have been a positive hindrance, due to the nerdiness factor. What prehistoric female would be interested in a male who wanted to think about whether a set could be equal in cardinality to its power set, instead of where to look for game?
This passage, written 140 years after Wallace’s, is eerily similar.
But in the time separating Wallace and Plantinga, we’ve come to understand a lot about evolution, and we know now that our overengineered brain is not a puzzle for science. It’s certainly true that our brain wasn’t molded by natural selection for future contingencies. That is indeed impossible under naturalism, and Plantinga is also correct that doing mathematics would not have improved the fitness of our preliterate ancestors. But once the human brain attained a certain state of complexity—and it has to be pretty complex to handle language and the skills of living in bands of hunter-gatherers—it already had the ability to perform novel tasks that had nothing to do with evolution. Likewise, a computer designed to do certain things can, when its hardware becomes sufficiently complex, do things never envisioned by its maker.
Lest you think that this answer is special pleading, realize that similar phenomena occur in many animals. Crows, for instance, can use reason to solve complicated puzzles designed by humans (of course, there must be a food reward at the end). Parrots can imitate human speech, and even sing opera arias, while lyrebirds can imitate chain saws and car alarms. These talents are by-products of skills acquired for living in nature. Species often solve novel problems never encountered in nature, like the famous blue tits of Britain, who learned in the 1920s to open milk bottles delivered to doorsteps and guzzle the cream from the top. Chimpanzees have learned to crack nuts with rocks, to “fish” for termites by dipping chewed grass stems into the nest entr
ances, and to make sponges out of masticated leaves to soak up drinking water.
None of these behaviors could have been direct objects of natural selection; all were side effects of other aspects of the brain and body that were presumably the result of natural selection. If the human brain was overdesigned, then so were the brains of other animals, including our closest living relatives. That is no problem for biology, but it is for theists who claim that the human brain was uniquely overdesigned by a god—probably to apprehend and worship that god.
Before we leave this topic, it’s worth noting that science is actually the best way to correct our false beliefs: beliefs that severed tetherballs fly away in spirals or that the Sun literally rises and sets. The elaborate cross-checking and doubt that pervade science, and the complicated instruments we’ve devised to supplement our senses, are all tools designed to check which of our beliefs are true.
Is Science the Only “Way of Knowing”?
All knowledge that is not the genuine product of observation, or of the consequence of observation, is in fact utterly without foundation, and truly an illusion.
—Jean-Baptiste Lamarck
One of the most common complaints of accommodationists and critics of “scientism”—the supposed overreaching of scientists that we’ll discuss shortly—is that science has no monopoly on finding truth. In The Language of God: A Scientist Presents Evidence for Belief, Francis Collins asserts that “science is not the only way of knowing.” The next sentence gives his alternative: “The spiritual worldview provides another way of finding truth.”
But these “other ways of knowing,” as they’re commonly called, include more than spirituality and religion. Additional candidates are the humanities, social science, art, music, literature, philosophy, and mathematics. The whole panoply of “other ways” is touted not just by advocates of the humanities defending their bailiwick, but also by theists who want to use their own “ways of knowing”—faith, dogma, revelation, scripture, and authority—to buttress their claims about the divine.
Faith Versus Fact : Why Science and Religion Are Incompatible (9780698195516) Page 24