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Not 'Just a Theory'

In science, the term 'theory' doesn't mean quite what it does in daily life, the New York Times' Carl Zimmer writes. The Times asked readers to write in about misperceptions that annoy them, and this got the most likes on its Facebook page.

"In everyday conversation, we tend to use the word 'theory' to mean a hunch, an idle speculation, or a crackpot notion," Zimmer notes. "That's not what 'theory' means to scientists."

Instead, a scientific theory "is a system of explanations that ties together a whole bunch of facts," Brown University's Kenneth Miller says. And Miller, Zimmer adds, has had to explain this misperception in court.

Miller co-wrote a high school biology textbook, and while Cobb County, Ga., adopted the textbook, the board of education required teachers to add a sticker to it that said that "[e]volution is a theory, not a fact, regarding the origin of living things." He testified for two hours in the ensuing lawsuit brought by parents to have the stickers removed.

He recalls that as he left the courtroom a woman said to him that "'[i]t's only a theory, and we're going to win this one.'" As Zimmer notes, the judge ruled against the board of education, and the board eventually agreed to remove the stickers.

The theory of evolution isn't the only theory that undergirds much of modern science, Zimmer adds. There's also the general theory of relativity, the theory that the sun is at the center of the solar system, and the germ theory of disease, he says.

"To the best of our ability, we've tested them, and they've held up," Miller says. "And that's why we've held on to these things."