Equivalence and the adaptationist program

Abstract

Equivalence guarantees comparison. Thus, one may make a legitimate comparison of all species which, if responding, are adapted to a certain condition with all species which, if not adapted, do not respond to this condition. Several ways in which this theme is elabored are presented. An insight into the way in which equivalence works is illustrated as follows. When an eastern woodchuck has a low elevation habitat, has a long growing season, has sexual maturation in the second year, has annual reproduction, and has an aggressive intolerant social system, this bundle of traits is adaptive of, maximizes the fitness of, woodchuck x. And the equivalent to ‘If x has the woodchuck bundle of traits, then this bundle is adaptive of x ′ is ‘If this bundle is not adaptive of x, then x does not have the woodchuck bundle of traits’. So, there are two steps wherein x stays the same: x has the woodchuck bundle; x does not have the woodchuck bundle. But there is a third step wherein an Olympic marmot as a different ‘ x’ has an opposite bundle of traits and thus does affirm the second equivalent ‘if the woodchuck bundle is not adaptive of x, then x does not have this bundle’. The process of adaptation, as when bird, adapted for flight, came from reptile, not adapted for flight, is really a three step process: x is adapted for flight, the same x is conceived as not adapted for flight, a different x (reptile) really is not adapted for flight. But this evolutionary metamorphosis of ‘adapted’ from ‘not adapted’ rests squarely on the mechanics of an equivalence, just like the one just mentioned for the woodchuck-marmot case. The adaptationist program says this: “each aspect of an organism's morphology, physiology and behavior has been molded by natural selection as a solution to a problem posed by the environment”. But the “wholesale reconstruction of a reptile to make a bird is considered a process of major adaptation by which birds solved the problem of flight”. The first quoted sentence says that each organism (or group of organisms) solved a problem and thus endorses only affirmation of ‘adapted’. The equivalence analysis behind the second quote endorses both affirmation and denial of ‘adapted’ in the process of adaptation. Thus, there is contradiction in the presentation of the adaptationist program by Lewontin.