Great explanation. A very clear way to explain the difference between a fact and a theory to those who just don't get it. How to explain to them it's not "either or" it's "both". Evolution is a fact AND a theory.
Posted on: December 30, 2007 9:25 AM, by Ed Brayton
After 3 days of being inundated with ignorant creationists and others spouting incredibly popular but absolutely wrongheaded claims about the meaning of "fact" and "theory" in science, I think it's a good idea to post what I think is the clearest and best explanation ever written of what those words mean in science. It comes from the late Stephen Jay Gould, written for Discover magazine in 1981. It sums up the difference between the vernacular and scientific meanings of those words perfectly. Excerpt below the fold:
In the American vernacular, "theory" often means "imperfect fact"--part of a hierarchy of confidence running downhill from fact to theory to hypothesis to guess. Thus creationists can (and do) argue: evolution is "only" a theory, and intense debate now rages about many aspects of the theory. If evolution is less than a fact, and scientists can't even make up their minds about the theory, then what confidence can we have in it? Indeed, President Reagan echoed this argument before an evangelical group in Dallas when he said (in what I devoutly hope was campaign rhetoric): "Well, it is a theory. It is a scientific theory only, and it has in recent years been challenged in the world of science--that is, not believed in the scientific community to be as infallible as it once was."
Well, evolution is a theory. It is also a fact. And facts and theories are different things, not rungs in a hierarchy of increasing certainty. Facts are the world's data. Theories are structures of ideas that explain and interpret facts. Facts do not go away when scientists debate rival theories to explain them. Einstein's theory of gravitation replaced Newton's, but apples did not suspend themselves in mid-air, pending the outcome. And humans evolved from apelike ancestors whether they did so by Darwin's proposed mechanism or by some other, yet to be discovered.
Moreover, "fact" does not mean "absolute certainty." The final proofs of logic and mathematics flow deductively from stated premises and achieve certainty only because they are not about the empirical world. Evolutionists make no claim for perpetual truth, though creationists often do (and then attack us for a style of argument that they themselves favor). In science, "fact" can only mean "confirmed to such a degree that it would be perverse to withhold provisional assent." I suppose that apples might start to rise tomorrow, but the possibility does not merit equal time in physics classrooms.
From the comments section. Yep, I've found Gould pretty much unreadable, difficult to understand and writes in a style that first assumes you have PhD in the subject and then have to unravel what he says. But his explanation in this rare case was understandable.
When Gould used the phrase "imperfect fact" not only does he show his pretension in his effort to bludgeon us with his in theory excellent command of the language, but he also totally misses the meaning. "Theory" in vernacular does not mean imperfect fact. It means "totally bogus shit."