Case Study: Catholic Perspective on Evolution #5

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Scientific certitude

Popular accounts of science--in textbooks, magazines, and television features--are often misleading about the certitude of scientific knowledge. Writers who explain science to the general public must simplify a host of complex matters to make them understandable and interesting. But this task frequently leads to oversimplification. Non-scientists are led to believe that science is essentially a stable body of factual knowledge. In reality, however, it is a dynamic process, constantly engaged in self-correction and even radical revision. Interpretation, guesswork, and imagination play a larger role in scientific study than most people are aware.

Consequently, knowledge derived from this inquiry has several distinct but overlapping levels of certitude. Some scientific matters are known to be factually true; that is, they are beyond doubt. Others are reasonable conjectures, generally accepted as true by specialists in the field. Still others are untested hypotheses awaiting verification through further work.

Let us take one case in point: *Australopithecus* was an ape-like creature who lived more than a million years ago in Africa. It is fact that his brain size averaged about 500 cc. and that his leg-bone had some humanlike features. It is, however, a conjecture that he walked upright much of the time; this is a reasonable guess but not so certain as the aforementioned facts. But it is only an hypothesis that his body gave rise to that of man. These distinct degrees of probable certitude are often blurred in many popular science articles.

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