DigitalSoldier
Honorary Master
Those who favor teaching alternatives to evolution in public school science classes often argue that evolution is "only a theory". The argument probably stems from a misunderstanding of the meaning of "theory" and "fact" in science, as opposed to the meaning in everyday life.
In everyday life, a "theory" often means a vague fuzzy concept with a suggestion of uncertainty and guesswork. "Theory" can imply an impractical idea that does not always work out. However, in science a theory is a consistent framework that explains observed facts and predicts other facts. A scientific theory must be consistent with all relevant facts. If a theory makes a prediction that is contrary to observation, then the theory must be revised or abandoned. An acceptable scientific theory is falsifiable; that is, we must be able to imagine an event that would disprove the theory if it was observed under certain circumstances. If the falsifying event cannot be observed, but events predicted by the theory are observed, then the theory is given higher credence.
In ordinary usage, a "fact" is considered to be absolutely true and undeniable. There is often an implication of eternal truth. An assertion of "fact" is considered to be either true or false with no intermediate gradation. However, science does not give an assurance of complete, undeniable truth. Assertions of fact in science have varying degrees of credibility. For example, the assertion that the "earth is flat" is very near the bottom of the credibility scale. The evidence against this proposition is so overwhelming that it would be silly or perverse to assign it a high credibility. The assertion that "apples fall downward" is very near the top of the credibility scale; it would be silly or perverse to deny the credibility of this proposition.
Scientists infer the credibility of facts or propositions in several ways. Direct observation is used whenever possible. However, direct observation of past evolution is not possible because there were no scientists living millions of years ago. Another method of determining credibility is "constructive" or "circumstantial" inference. If a large constellation of data points to the construct and few or no data negate the construct, the credibility is high.
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