Phil Torres

This is a quick introduction to philosophical issues surrounding Darwinian theory. It is not a description of Darwinian theory itself—for that one should consult a textbook—but a discussion of such questions as: Why believe in evolution? Why is evolution a better explanation of the history of life than, say, the Bible (or Koran, or Buddhist mythologies, etc.).

To begin, philosophers recognize that “belief” and “knowledge” are two distinct things. The relationship is approximately this: Whenever one has knowledge one also has belief, but one can have belief without having knowledge. In other words, knowing entails believing, but believing does not entail knowing. Thus, knowledge is something more than belief; it is belief plus something. But what is this something?

This something cannot just be that the belief is true. If that were the case, then we would say that lucky guessers have knowledge, which seems very strange and incorrect. Instead, what distinguishes knowing something X and merely believing X is that the former involves justification: to know X we have to be justified in believing X (and X also has to be true, of course.) Especially since the eighteenth-century Enlightenment, philosophers have taken evidence to be the thing that justifies one’s beliefs, thereby making those beliefs knowledge. This "epistemological" position is called “evidentialism.”

A very appealing feature of evidentialism is that everyone accepts it in almost every situation. For example, if I—a relatively impecunious graduate student—pull up to your house and announce that I drove my Porsche there, you would no doubt be incredulous. Why? Because the evidence, i.e., the datum that I'm a poor student, suggests that Porsches are beyond monetary reach, and therefore I didn't drive a Porsche. To confirm your hypothesis, or tentative belief, about my not having a Porsche, you would no doubt walk to the window to see if a Porsche is in the driveway.

If the Porsche is there, you might be a bit confused at first, and your prior belief that I couldn’t own a Porsche because of my financial situation would have to be revised. If the Porsche isn’t there, though, your prior belief would be confirmed, and you would turn around and call me a liar! Either way, empirical evidence is the sole arbiter or judge of what you end up believing.

Many, many other examples from everyday life evince the exact same reliance on evidence for the justification of our beliefs. Indeed, if you didn’t put so much weight on evidence mediated through your senses, what would stop you from trying to walk through a wall? Of course, you believe there’s a wall there because of the evidence—and it's a very good thing you do!

The evidentialist position, therefore, is just common-sense with a jargonistic term. And that is precisely what science is—common-sense, albeit extended and refined into a rigorous and sophisticated form. With science, rather than believing, for example, that I own (or don't own) a Porsche without looking out the window, science takes care to make observations and experiments to use the evidence gained as the arbiter between competing hypotheses. It was during the Scientific Revolution that this empirical methodology was explicitly formulated by philosophers such as Francis Bacon.

It goes without saying that modern science has been hugely successful in its ability to explain and predict natural phenomena, from the submicroscopic to the astronomical. And the formation of the scientific method and subsequent reliance on evidence is entirely responsible for this. At the same time, as the scientific enterprise grew, Western religion became increasingly irrelevant. But why is this? To begin, in contrast to the evidentialism of science, religion advocates “blind faith,” or belief without evidence. For instance, the Biblical literalist, without any observations or experiments, believes in demon possession, resurrections, geocentrism, Divine Right, global floods, and virgin births (parthenogenesis). They believe that Methuselah lived to be 969 years old, that Balaam’s donkey actually spoke, and that Moses parted the Red Sea.

The only “evidence” for these beliefs is Scripture itself, which textual critics since John Mill several centuries ago have shown to be extremely unreliable. Indeed, not only are there major discrepancies within the Bible (e.g., When Jesus was born, 4 B.C.E. or 7 C.E.?), but between the Bible and other historical records (e.g., Did the census of Quirinius occur?). Problems of textual coherence and historical accuracy, though, are tangential to the subject of this paper. (See, e.g., Bart Ehrman's Misquoting Jesus for an accessible introduction to higher and lower textual criticism.)

The point is this: Science explicitly relies on evidence, and religion explicitly does not. Thus, whereas science acquires knowledge through empirical observation and experimentation, testing an hypothesis over and over again to assess its veracity, religion acquires knowledge through revelation, which is subject to no such confirmation.

When one reflects on this for a moment, it becomes clear that not relying on evidence is extremely peculiar, and even dangerous. For example, imagine going to the doctor with a worrisome symptom and, without examining your body, the doctor proclaims that she’s communicated with an invisible, tasteless, odorless, etc. entity of the spiritual realm, and that this entity says your condition is benign. Of course, no one would be satisfied with this, and one might even suspect that the doctor is schizophrenic. But this is exactly what religion does with respect to, for example, the origin of species: Rather than looking at the evidence, it looks at what a book written many millennia ago—in the Iron Age—has to say, and bases its beliefs on that.

In contrast, Darwinian theory is an explanation of origin of species based on the evidence available. Darwinism attempts to provide knowledge, not mere belief or “blind faith,” and as such it makes its theoretical foundation the exact same principles of evidentialism and methodological naturalism that physics, geology, astronomy, chemistry, psychology, sociology, medicine, and every other scientific discipline is built on.

If one doesn’t like what these principles have led to in the case of Darwinism, then one ought to be consistent and throw out the rest of science altogether. Again, science is just an extension of everyday common-sense, and since evolution is science, the syllogism concludes that evolution too is common sense. This is to say that any reasonable person who seriously looks at the evidence, considers the possible explanations and does this with the spirit of intellectual honesty will come to the same basic conclusion at which Darwin arrived. This conclusion is as sure as: “I don’t see a Porsche in the driveway, therefore you’re a liar!”

Not only is evolutionary theory supported by evidence—and therefore not mere belief but knowledge—but it is very solidly supported by available evidence. In fact, the evidence is so strong for evolution that one would have an extremely hard time finding even a single biologist at any academic institution around the world that doesn’t accept it—with the exception of religious institutions like Liberty University. Even the intelligent designers such as Behe and Dembski reject the Bishop of Usher’s estimation of the universe’s origin at 4004 B.C.E. (according to Old Testament genealogies). Instead, these neo-creationists accept, along with physicists, geologists, and biologists, that the earth is at least millions of years old. Talk about the evolution of Christian cosmogony!

In addition to the huge quantity of evidence supporting evolution—far more evidence for it in 1859 than for Einstein’s theory of relativity when the scientific community accepted it—Darwinian evolution has had an unprecedented and profound unifying affect in Biology. Indeed, with the theoretical marriage of Mendelian genetics and Darwinian theory in the "Modern Synthesis," the discipline of biology, as we know it today, was born. Eventually, the last stronghold of Lamarckism, namely microbiology, was defeated with the discovery (by Joshua Lederberg) of bacterial conjugation, in which bacteria exchange genetic material. At this point, even the microbiological domain was subsumed under the theoretical aegis of evolutionary theory, making Biology a massive and highly coherent field of study.

This merger of genetics and evolution is no doubt responsible for the amazing success and coherence of modern medicine; in fact, the abstract structure of Darwin’s theory of natural selection was even explicitly borrowed to explain the production of T-cells in the immune system: Right now, as you read this sentence, T-cells in your thymus are undergoing natural selection, just like organisms have the wild for 3.5 billion years. Indeed, if the status of a theory is determined by its fecundity—or how fruitful it’s been—then Darwinism ranks among the greatest theories ever devised by any human mind.

One final note on the relation between science and evidence. I say above a number of times “available evidence.” This is important to note because, as technologicial innovations allow us to peak deeper and deeper into corners of the universe previously beyond our observational reach, the store of evidence upon which to build a theory inevitably increases. Two basic possibilities can occur: (i) sometimes putative “facts” are refuted by further testing (i.e., are shown not to be facts at all, but errors of mistaken observation), and (ii) sometimes just adding facts (without changing what’s already there) means changing the "evidential landscape," so to speak. Both may entail a corresponding modification in one's hypothesis, or the abandonment of that hypothesis altogether.

Recall that a justified belief is one with supporting evidence. What are the implications of this? Well, it means that such beliefs as geocentrism, or that the sun revolves around the earth, might once have been justified—that is, given the evidence available to humans many millennia ago. But what’s the difference between humans millennia ago and ourselves? This is an extremely important question, and one that Thomas Kuhn draws attention to in proposing his model of scientific development. According to Kuhn, the standard historiography of science looks only at the "heroes" of scientific achievement, ignoring the myriad theories or "paradigms" (one of many uses of this term) that scientists later jettisoned, such as phlogiston theory. This approach is now pejoratively called the "Whiggish" approach.

The difference between humans today and humans in the past is only a matter of degree. This is to say, our theories are better than theirs—closer to the truth, one might say (although Kuhn would disagree)—only because the evidence available to us is much greater. But imagine 2,000 years from now. What will the evidence be like then? At the present rate of change in science, not to mention development of technology, it’s almost certain that our theories will be different—maybe radically different—as more and more evidence becomes available. This means, of course, that our current theories, Darwinism included, might be wrong (either incomplete or incorrect) just like the old theory of geocentrism. The philosophical position whereby one admits that she might always be wrong, under any circumstances, is called “fallibilism.”

So where does this leave us? Why accept today’s scientific theories if they’re likely to be wrong tomorrow? Why not turn to religion, which offers supposedly immutable truths—beliefs that resist the common-sense tendency towards evidentialism, beliefs to which one can cling no matter what the evidence is. These are precisely the reasons many religious people give when asked why they reject evolutionary theory, or the conclusions of science more generally. (Although, with the notable exception of Christian Science, religious people still go to the doctor for diagnosis and treatment rather than the Shaman or priest, and therefore implicitly accept scientific conclusions to some extent.)

The response to this position comes in two parts: First, when one takes an historical view of the putative “truths” of the Bible, one finds that many of them have changed. Contemporary intelligent designers are but one example: As mentioned above, unlike the literalistic early twentieth century Young Earth Creationists, Behe and Dembski both accept that the earth is far older than Scripture suggests. They just don't accept, for example, that certain complexities of biochemistry could have come about through natural selection. Thus, not even these triumphalists of neo-creationism accept the former “truth” that the earth is much younger than scientists say, as found in Old Testament genealogies.

Second of all, the tentative and provisional nature of scientific theories is strongest and most commendable feature of science. "Dogmatic clinging to beliefs as evidence changes and expands never got anyone anywhere." Every reasonable person accepts this, even if only tacitly—again, proof is that people go to the doctor rather than to the Shaman, or preist. And indeed, while Shamanism might have, at one point long ago, been a rational method of treating sick individuals, the evidence today points away from Shamanistic practices and towards the theories behind modern medicine. And where the evidence points, we must go!

In the future, of course, the evidence might point away from current theories and towards some new set of theories. Fine. The take-home point is that in all of these cases evidence is doing the pointing, not mere belief or “blind faith.” Thus, even if Darwinian theory, for example, ends up being wrong (either incomplete or incorrect), it is still founded on empirical evidence, and therefore is far better off an explanation of certain natural phenomena than the Bible (or the Koran, or Buddhist mythologies, etc.)

There is, in fact, no logical contradiction (although there would be a theoretical one!) with discovering, much to our surprise, a pre-Cambrian rabbit. (Mammals appeared on the evolutionary scene only after the Cambrian explosion.) Such a huge anomaly would throw Darwinism into total theoretical chaos, falsifying its fundamental claim of common descent with modification. In this case, another theory would have to be put in its place. At no point, though, would anyone propose a replacement theory not based on the evidence. Indeed, this would violate the common-sense approach to which science is dedicated. But religious explanations do exactly this, and that is why they are not as good as those that science gives, even if they end up wrong.

In conclusion, the methodological approach of science is extremely intuitive, based on common-sense reliance on evidence as the arbiter between beliefs. Darwinian theory too is based on this approach: Darwin made observations, and from those observations proposed an extremely convincing explanation—just as you would have peered through the window to see if a Porsche was in the driveway, and from that observation formed a belief about my fantastical claim of being an impecunious student and owning a Porsche.

Thus, there is nothing arbitrary or dogmatic about espousing evolutionary theory, and whether or not Darwinism turns out to be true is completely independent of whether or not it is a good theory—of whether or not one is justified to accept it, given the available evidence. It is, in fact, precisely because of the available evidence that belief in Darwinism counts as knowledge, rather than mere belief.

© 2008 Phil Torres. Do not reproduce or cite without permission.