What is the structure of evolutionary theory? The question seems to presuppose a unique right answer. But the relevant notion of structure is highly relative to broad philosophic theories about scientific theories. At present no one such theory dominates. One once did. It went by the name ‘Logical Positivism’. During its heyday a unique right answer to our question might have been expected. There is no reason to expect one now.

Not only should one not suppose that there is a uniquely correct structural description of evolutionary theory, neither should one suppose that giving a structural description of evolutionary theory is essentially uncovering what is implicit in biological work. That approach is appropriate only when conceptual fossilization has occurred. In the case of evolutionary theory molding is more appropriate than uncovering.