The Corner

More Don’t Know Much About Biology

One thing that is becoming clear to me, reading all these e-mails, is that

lots of people don’t understand what science is. Many people, for example,

tell me that: “Evolution can’t explain the origin of life.” Well, I think

that is true, but so what? Evolution can’t explain the spectrum of a

quasar, either, or superconductivity, or Alzheimer’s disease, or continental

drift. A scientific theory is not required to explain everything, only some

finite set of observed facts. Evolution is a hypothesis to explain the

variety of living things. So far as I can see, it does that very well. It

is perfectly consistent with the hypothesis that life got started by a

miracle, or with several other different hypotheses. Other people want to

tell me that believing in evolution is just as much a matter of faith as

believing in Creationism. Well, to the degree that all non-mathematical

knowledge is merely probable, not certain, that is true too–”trivially

true,” as mathematicians say. I believe I am actually sitting at my desk

typing a post to The Corner. It is possible I am dreaming this, or

hallucinating it, and to that degree my belief involves an act of faith. It

does NOT follow that every theory is as good as every other. Some fit the

evidence better than others, or offer more reliable predictions. THERE ARE

DEGREES OF PROBABILITY. It’s not so much that Creationist arguments are

wrong, as that they miss the whole point of scientific inquiry. “Evolution

can’t explain everything.”–No, it can’t; scientific theories don’t have to.

“Evolution isn’t certain.”–No, it’s not; scientific knowledge never is.

“Evolution requires an act of faith.”–Yes, it does; so does walking across

the room. “You can’t conduct laboratory experiments to verify

evolution.”–No, you can’t; nor to verify theories about the formation of

stars, or the state of affairs at the center of the earth, or the

composition of Jupiter’s atmosphere. All sorts of science goes on outside

laboratories. Etc. etc. Sometimes, though, the Creationists are just

wrong. “Evolution has no predictive value,” several readers say. Not so.

If, in rocks 80 million years old, I discover a fossil of creature A, and in

rocks 40 million years old I discover a fossil of creature B, and if B looks

to be a developed or advanced form of A, then I may reasonably predict that

in rocks 60 million years old I shall find a creature intermediate in form

between A and B. And in fact this happens all the time. It’s a good

theory. Of course, new observations might come up that require us to modify

the theory, or even scrap it completely–that is the nature of science.

Scientists–good scientists–are not dogmatic. They respect physical

evidence, and are always ready to change their minds accordingly. A hundred

years ago, no geologist believed in continental drift; now they all believe

in it. The evidence was overwhelming. Biologists don’t reject Creationism

because they are blinkered dogmatists. They reject it because it explains

nothing they can’t already explain with simpler hypotheses.

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