By Richard Dawkins
A little learning is a dangerous thing. This has never struck me as a particularly profound or wise remark, but it comes into its own when that little learning is in philosophy. A scientist who has the temerity to utter the t-word--true--is likely to encounter philosophical heckling that goes something like this:
"There is no absolute truth. You are committing an act of personal faith when you claim that the scientific method, including mathematics and logic, is the privileged road to truth. Other cultures might believe that truth is to be found in a rabbit's entrails or the ravings of a prophet atop a pole. It is only your personal faith in science that leads you to favour your brand of truth."
That strand of half-baked philosophy goes by the name of cultural relativism. It is one aspect of the Fashionable Nonsense detected by Alan Sokal and Jean Bricmont, or the Higher Superstition of Paul R. Gross and Norman Levitt. The feminist version is ably exposed by Noretta Koertge, coauthor of Professing Feminism: Cautionary Tales from the Strange World of Women's Studies:
Women's Studies students are now being taught that logic is a tool of domination. ...The standard norms and methods of scientific inquiry are sexist because they are incompatible with "women's ways of knowing." ...These "subjectivist" women see the methods of logic, analysis, and abstraction as "alien territory belonging to men" and "value intuition as a safer and more fruitful approach to truth."
How should scientists respond to the allegation that our "faith" in logic and scientific truth is just that--faith--not "privileged" over alternative truths? An obvious response is that science gets results. As I once wrote, "Show me a cultural relativist at 30,000 feet, and I'll show you a hypocrite. ...If you are flying to an international congress of anthropologists or literary critics, the reason you will probably get there--the reason you don't plummet into a ploughed field--is that a lot of Western scientifically trained engineers have got their sums right." Science supports its claim to truth by its spectacular ability to make matter and energy jump through hoops, and to predict what will happen and when.
But let's go further: Is it just our Western scientific bias to be impressed by accurate prediction, to be impressed by the power to sling rockets around Jupiter to reach Saturn, or intercept and repair the Hubble telescope, to be impressed by logic itself? Well, let's concede the point and think sociologically, even democratically. Suppose we agree, temporarily, to treat scientific truth as just one truth among many, and lay it alongside all the rival contenders: Trobriand truth, Kikuyu truth, Maori truth, Inuit truth, Navajo truth, Yanomamo truth, !Kung San truth, feminist truth, Islamic truth, Hindu truth. The list is endless--and thereby hangs a revealing observation. In theory, people could switch allegiance from any one "truth" to any other if they decided it had greater merit. On what basis might they do so? Why would one change from, say, Kikuyu truth to Navajo truth? Such merit-driven switches are rare--with one crucially important exception: switches to scientific truth from any of the others. Scientific truth is the only member of this endless list that evidentially convinces converts of its superiority. People are loyal to other belief systems because they were brought up that way, and they have never known anything better. When people are lucky enough to be offered the opportunity to vote with their feet, doctors prosper and shamans decline. Even those who do not, or cannot, avail themselves of a scientific education choose to benefit from technology made possible by the scientific education of others.
As religious missionaries claim converts in the underdeveloped world, they succeed not because of the merits of their religion but because of the science-based technology for which it is pardonably, but wrongly, given credit. You can imagine the tribal warrior thinking, "Surely the Christian God must be superior to our Juju, because Christ's representatives come bearing rifles, telescopes, chain saws, radios, almanacks that predict eclipses to the minute, and medicines that work."
So much for cultural relativism. A second type of truth-heckler prefers to drop the name of Karl Popper or, more fashionably, Thomas Kuhn. According to their arguments, there is no absolute truth. Scientific truths are merely hypotheses that have so far failed to be falsified and are destined to be superseded. At worst, after the next scientific revolution, today's "truths" will seem quaint and absurd, if not actually false. In this view, the best we scientists can hope for is a series of approximations that progressively reduce errors but never eliminate them.
The Popperian heckle partly stems from the accidental fact that philosophers of science are obsessed with one piece of scientific history: the comparison between Newton's and Einstein's theories of gravitation. It is true that Newton's simple inverse square law has turned out to be an approximation, a special case of Einstein's more general formula. If this is the only piece of scientific history you know, you might indeed conclude that all apparent truths are mere approximations, fated to be superseded.
The flat pattern of ink on paper is compatible with two alternative hypotheses of solidity. We see a solid cube that, after a few seconds, flips to a different cube, then flips back to the first cube, and so on. Thus, goes the argument, sense-data may only confirm or reject mental hypotheses about what is out there. We are lost in a cognitive hall of mirrors, never able to escape our reflection to see the real world.
This line of thought--that all our percepts are hypothetical models in the brain--might lead us to fear for our descendants when the blurring between reality and illusion will be even more pronounced, thanks to computers capable of generating vivid models of their own. But what is new about any of this? Without venturing into the high tech worlds of virtual reality, we already know that our senses are easily deceived. Magicians and professional illusionists can persuade us that, if we lack a sceptical foothold in reality, something supernatural is going on. Indeed, some notorious erstwhile conjurers have made a fat living doing exactly that--a living much fatter than they ever enjoyed when they frankly admitted that they were faking it.
Scientists, alas, are not best equipped to unmask telepathists, mediums, and spoon-bending charlatans. This is a job best handled by professionals, and that means other conjurers. The lesson that conjurers, the honest variety and the impostors, teach us is that an uncritical faith in our own sense organs is not an infallible guide to truth.
Fine, but none of these theories undermines our understanding of what it means for something to be true. If I am in the witness box and prosecuting counsel wags his finger sternly and demands, "Is it or is it not true that you were in Chicago on the night of the murder?" I should get pretty short shrift if I replied, "What do you mean by true?" Or, reverting to the first heckle, I would not expect a jury, even a Bongolese jury, to give a sympathetic hearing to my plea, "It is only in your Western scientific sense of the word in that I was in Chicago. The Bongolese have a completely different concept of in, according to which you are only truly in a place if you are an anointed elder entitled to take snuff from the dried scrotum of a goat."
It is simply true that the sun is hotter than the earth, true that the desk on which I am writing is made of wood. These are not hypotheses awaiting falsification, not temporary approximations of an ever elusive truth, not local truths that might be denied in another culture. They are just plain true. It is forever true that DNA is a double helix, true that if you and a chimpanzee (or an octopus or a kangaroo) trace your ancestors back far enough, you will eventually hit a shared ancestor.
To a pedant, these are still hypotheses that might be falsified tomorrow. But they never will be. Strictly, the truth that there were no human beings in the Jurassic era is still a conjecture, which could be refuted at any time by the discovery of a single human fossil, authentically dated by a battery of radiometric methods. It could happen. Want to bet? These are just truths, even if they are nominally hypotheses on probation. They are true in exactly the same sense as the ordinary truths of everyday life are true, true in the same sense as it is true that you have a head and that my desk is wooden. If scientific truth is open to philosophic doubt, it is no more so than commonsense truth. Let's at least be evenhanded in our philosophical heckling.
But now, having refuted the two most common attacks on the scientific concept of truth, let me present another, more difficult challenge. It is that science is very much not synonymous with common sense. Admittedly, that doughty scientific hero Thomas H. Huxley said:
Science is nothing but trained and organised common sense, differing from the latter only as a veteran may differ from a raw recruit: and its methods differ from those of common sense only as far as the guardsman's cut and thrust differ from the manner in which a savage wields his club.
But Huxley was talking about the methods of science, not its conclusions. And those conclusions can be disturbingly counterintuitive. Quantum theory is counterintuitive to the point where the physicist sometimes seems to be battling insanity. We are asked to believe that a single quantum behaves like a particle in going through one hole instead of another but simultaneously behaves like a wave in interfering with a nonexistent copy of itself, if another hole is opened through which that nonexistent copy could have travelled (if it had existed).
It gets worse, to the point where some physicists resort to a vast number of parallel but mutually unreachable worlds that proliferate to accommodate every alternative quantum event. Other physicists, equally desperate, suggest that quantum events are determined retrospectively by our decision to examine their consequences. Quantum theory strikes us as so weird, so defiant of common sense, that even the great physicist Richard Feynman was moved to remark, "I think I can safely say that nobody understands quantum mechanics." Yet the many predictions by which quantum theory has been tested stand up, with an accuracy so stupendous that Feynman compared it to measuring the distance between New York and Los Angeles accurately to the width of one human hair. On the basis of these stunningly successful predictions, quantum theory, or some version of it, seems to be as true as anything we know.
Modern physics teaches us that there is more to truth than meets the eye, or more than meets the all-too-limited human mind, evolved as it was to cope with medium-size objects moving at medium speeds through medium distances in Africa. In the face of these profound and sublime mysteries, the low-grade intellectual poodling of pseudophilosophical poseurs seems unworthy of adult attention.