Philosophy of Science and the Theory of Natural Selection

Toulmin, Hull, Campbell, and Popper have defended an "Evolutionary-Analogy" view of scientific evaluative practice. In this view, competing concepts, theories and methods of inquiry engage in a competitive struggle from which the "best adapted" emerge victorious. Whether applications of this analogy contribute to our understanding of science depends on the importance accorded the disanalogies between natural selection theory and scientific inquiry. Michael Ruse has suggested instead an "Evolutionary-Origins" view of scientific evaluative practices in which scientific inquiry is directed by application of epigenetic rules that have become encoded in homo sapiens in the course of evolutionary adaptation. Among these rules are "formulative theories that are internally consistent," "seek severe tests of theories," (Popper) and "achieve a consilience of inductions" (Whewell). As a descriptive theory of science, the "Evolutionary-Origins" view is prima facie inconsistent with evidence that human beings often make decisions that violate the "genetically-hard-wired rules." As a normative-prescriptive philosophy of science, the "Evolutionary-Origins" view is limited by the fact that in biological evolution, adaptation to present pressures may be achieved at the expense of a loss of adaptability (the capacity to respond creatively to future changes in environmental conditions).

In the 1980s, the hitherto-dominant normative-prescriptive conception of philosophy of science became the subject of a debate which continues to the present time. Some philosophers of science suggested that the proper aim of the discipline is the description of scientific evaluative practice.

There is a modest version and a robust version of descriptive philosophy of science. The aim of the modest version is the historical reconstruction of actual evaluative practice. Given that scientists preferred one theory (explanation, research strategy...) to a second, the modest descriptivist seeks to uncover the evaluative standards whose application led to this preference. For instance, the modest descriptivist may seek to uncover the standards implicit within such evaluative decisions as Aristotle's rejection of pangenesis, Newton's rejection of Cartesian Vortex Theory, or Einstein's insistence that the Copenhagen Interpretation of quantum mechanics is incomplete. Pursuit of a modest descriptive philosophy of science may require a certain amount of detective work, particularly for episodes in which the pronouncements of scientists and their actual practice do not coincide.

The conclusions reached by modest descriptive philosophy of science are subject to appraisal by reference to standards applicable to historical reconstruction in general. There is no distinctively philosophical task of appraisal. The modest descriptivist is a historian with a particular interest in evaluative practice.