The argument is disarming. Living organisms are often remarkably adapted for a particular purpose鈥攕o much so that it seems as if they must have been created by a purposeful designer. And, at first blush, that theory appears much more plausible than the proposition that the exquisite complexity of nature arose entirely by unplanned, natural causes. Why then do we refuse to allow the creationist model to be presented and discussed in science class as an alternative to the theory of evolution? Isn鈥檛 science supposed to be open to opposing opinions? Are we not repeating the error of those who refused to look through Galileo鈥檚 telescope for fear that they might discover something new? Why can鈥檛 we, in the words of President George W. Bush, 鈥渢each the controversy鈥�?
The argument is a hardy perennial. An Education Week article from late last year (鈥淓volution Projects Yield Results,鈥� Nov. 17, 2010) described a National Science Foundation-supported project that teaches 鈥渆volution readiness鈥� to 4th graders by having them run virtual experiments with computer models that evolve by natural selection. As the director of that project, I feel strongly that creationism has no place in science class.
My opinion is that creationism in all its forms, including 鈥渋ntelligent design,鈥� is not science; and that it is vitally important that we not teach nonscience as if it were science.
Creationism is not science because it introduces causes outside of nature in order to explain observations of nature.鈥�
The early-20th-century physicist Wolfgang Pauli, known equally for his exclusion principle and his biting wit, once famously said of a proposed theory in a research paper, 鈥淣ot only is it not right, it鈥檚 not even wrong.鈥� The identity of the research paper that incurred Pauli鈥檚 displeasure is lost to history, but his quip is an apt description of the assertion that the adaptations of organisms can be 鈥渆xplained鈥濃�攐r 鈥渆xplained away鈥濃�攂y positing that an unknown and unknowable entity designed them that way. Such a theory can, in fact, never be proved wrong. It can never even be revised because, in contrast to evolution, which has undergone continual revision since Darwin鈥檚 day, creationism makes no testable predictions other than the trivial one that living creatures should look as though they were designed.
Creationism is not science because it introduces causes outside of nature in order to explain observations of nature. Theories like that do not foster inquiry; rather, they close off discussion. Discoveries of seemingly 鈥渄esigned鈥� organisms are taken as 鈥減roof鈥� of the theory, and observations of suboptimal design are viewed as indications that the external designer, though 鈥渋ntelligent鈥� is not 鈥減erfect.鈥� When all the fuss is over, nothing is ever discovered鈥攐r can ever be discovered鈥攖hat sheds new light, connects previously disconnected data, offers new insights, or generates new knowledge.
That鈥檚 why creationism shouldn鈥檛 be taught as science, not because it鈥檚 wrong, but because it isn鈥檛 science. (Though I would certainly support, and would love to teach, a class that contrasted creationism and science in order to help students appreciate the difference.)
So why is it so important that we not teach nonscience as science?
It is important because science and nonscience are radically different, and the difference has critical implications. Scientific theories make testable predictions about the world, predictions that often extend well beyond anything the inventor of the theory had in mind.
Darwin had never heard of the DNA molecule, so he couldn鈥檛 possibly have anticipated its role in evolution. A century later, when the central function of DNA as the carrier of genetic information was discovered, Darwin鈥檚 theory of evolution predicted that the DNA of different species ought to differ in very specific ways. For example, two species that diverged from a common ancestor鈥攕ay dogs and wolves鈥攁 few million years ago (relatively recently in evolutionary terms) ought to have very similar DNA. However, more distantly related species鈥攇iraffes and skunks, or snakes and butterflies鈥攁re predicted to be less similar at the molecular level because they diverged from a common ancestral species hundreds of millions of years ago. In other words, the more recently any two species diverged from their ancestral species, the more similar their DNA ought to be.
This is a powerful prediction! It opens up a whole new line of evidence, entirely unknown to Darwin and his contemporaries, that enables one to construct a 鈥渇amily tree鈥� comprising all living things on earth.
The DNA evidence is accumulating rapidly, and evolution still stands tall. It turns out that subtle differences in the DNA of humans from different subpopulations may have profound implications for combating disease. Scientists are sorting out the details, but the basis of the technique is pure evolution. People who have lived for many generations in parts of the world where a certain disease is endemic have been subjected to intense selective pressure, affecting their genetic makeup. In other words, these individuals have evolved to acquire a resistance to the disease. By studying their DNA, we may be able to put that knowledge to work for the rest of us some day.
It鈥檚 an exciting approach to solving an important problem, and it would never have occurred to anyone if we had just left it at, 鈥淟iving creatures look designed, so there must be a designer.鈥� Or, 鈥淲e don鈥檛 know anything about this designer, and there鈥檚 no way to find out anything, so let鈥檚 just leave it at that.鈥�
The goal of science is to discover things, to create new knowledge, to understand new phenomena. Nonscience does none of these things. Confronted by something it can鈥檛 explain, nonscience introduces another element it doesn鈥檛 understand for the purpose of explaining what it originally could not. Not only does this lead to an infinite regress (who designed the designer?), it also eliminates, even worse, any opportunity to discover natural explanations for natural phenomena. And that makes a huge difference.
We live in an age when the extraordinary success of science has brought with it unprecedented problems that can be solved only with the help of science. For this reason alone, to allow nonscience to be taught as though it were science would be a mistake of literally global dimensions.
