In his Aug. 24 letter on evolution, Daniel P. McKim displays some widely held misconceptions about the nature of science and of evolutionary biology in particular. In listing "questions that evolution must answer to be considered true science," he implies that science is a set of final answers, whereas it is first and most importantly a process for finding answers. He seems to think that a "true science" no longer has unanswered questions. Fortunately, no field of science has arrived at this state of stultification; rather, every new answer seems to lead to more questions. As a result, we keep finding limits to the domains within which our theories apply.

The idea that life evolved from nonlife does not "contradict" the law of biogenesis so much as it points out the natural limits of that law: Under conditions very different from those of today, the law could, and doubtless did, break down. In the same way, Newton's laws break down under certain exotic physical conditions, as described by Einsteinian relativity, yet physics remains a "true science."

As for "any species giv[ing] birth to a life form that is superior or more sophisticated than itself," it is fantasy to think that this happens in one obvious jump, such as a bird hatching from a reptile's egg. In reality, the "proven scientific law" of natural selection simply fine-tunes the adaptation of each species to its changing environment. Only in retrospect, after many generations, does it occasionally become apparent that this has gradually and serendipitously led to something that is "superior" on someone's scale of measurement (rather than merely just as good but different). Such major "technological breakthroughs" in life are rare and don't suddenly appear full-blown -- but they are statistically certain to occur.

Characteristic of creationist thinking is the insistence on putting evolutionary biology into a different category from all other fields of science and judging it by different, ad-hoc criteria. This is special pleading disguised as logical rigor.

DARYL P. DOMNING

Washington