Monday, February 16, 2009

Nobody "believes" in evolution.

In honor of Darwin's 200th birthday, a Gallup poll found that fewer than 40% of Americans believe in the theory of evolution. While we should be concerned about the low levels of understanding of Darwin's theory in this country, this poll may exaggerate the extent of that lack of understanding. The poll asks the wrong question, a question that reveals the pollster's own lack of understanding of the scientific process.

Science is antithetical to belief. Science does not ask for belief, but instead allows for hypotheses that are tested by experiment. To the extent experiments prove the validity of those hypotheses, they become accepted as theories. Those scientific theories remain valid, unless and until they are disproved and superseded by a better theory. Scientific theories are not valid because a lot of people believe in them, or even because a lot of scientists accept them. They are valid only because they continue to have explanatory power in the face of repeated challenges.

To ask people if they "believe" in a particular theory, is to tell responders that a scientific explanation stands on no different footing from any other kind of explanation, whether based on religion or culture or a pseudo-science like astrology. So responders are free to believe it or believe in something else as they choose. The question actually gives credence to those fundamentalists who argue that Darwinism is some kind of secular religion that has its own creed and adherents and that should be given no higher status in school than the "theory" of creationism. Think how absurd the question would sound if a pollster asked people if they "believe" in gravity, or if they "believe" that the earth revolves around the sun. People ought not to be permitted to reject a scientific theory simply because they choose not to believe in it. You can reject a scientific theory if you have done an experiment that challenges the validity of the theory. Or you can say that the scientific explanation is not the whole explanation, or that it does or does not conflict with other beliefs you hold. Or you can just admit that you don't understand it. All those answers are acceptable. But it is pointless to say that you don't "believe" in a particular scientific theory. It is equally pointless to say that you do believe in it.

Maybe I'm quibbling by objecting to the language used in this poll, but I think it is important to insist on better terminology. The kind of confusion revealed by Gallup's questions lies at the heart of uninformed debate about not only evolution, but other scientific issues such as climate change. Journalists repeatedly make the mistake of thinking that these questions can be resolved by debate, or that they are matters of opinion. They are not. Questions such as whether or not human activity is causing the temperature to rise, or whether species evolve by natural selection cannot be resolved by debate, and are not matters of opinion. They can only be decided by the scientific process.

It would have been better for Gallup to ask whether people understand the theory of natural selection, or even whether they accept the theory. It might also be useful to ask more specific questions, such as whether people understand that when antibiotics kill germs, only the strongest germs survive. Or whether genes can mutate. Or whether finches with a particular shape of beak are more likely to survive a drought. Asking questions like that would probably give slightly more reassuring answers about the average person's understanding of natural selection, or at least expose their ignorance. Those kinds of questions would be more respectful of Darwin's legacy, and of science.

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