The claim that conceptual systems change is a platitude. That our conceptual systems are theory-laden is no less platitudinous. Given evolutionary theory, biologists are led to divide up the living world into genes, organisms, species, etc. in a particular way. No theory-neutral individuation of individuals or partitioning of these individuals into natural kinds is possible. Parallel observations should hold for philosophical theories about scientific theories. In this paper I summarize a theory of scientific change which I set out in considerable (...) detail in a book that I shall publish in the near future. Just as few scientists were willing to entertain the view that species evolve in the absence of a mechanism capable of explaining this change, so philosophers should be just as reticent about accepting a parallel view of conceptual systems in science evolving in the absence of a mechanism to explain this evolution. In this paper I set out such a mechanism. One reason that this task has seemed so formidable in the past is that we have all construed conceptual systems inappropriately. If we are to understand the evolution of conceptual systems in science, we must interpret them as forming lineages related by descent. In my theory, the notion of a family resemblance is taken literally, not metaphorically. In my book, I set out data to show that the mechanism which I propose is actually operative. In this paper, such data is assumed. (shrink)

Introductory Abstract Philosophers of science, in the course of making a sharp distinction between the tasks of the philosopher and those of the scientist, have pointed to the possibility of an empirical science of induction. A comparative psychology of knowledge processes is offered as one aspect of this potential enterprise. From fragments of such a psychology, methodological suggestions are drawn relevant to several chronic problems in the social sciences, including the publication of negative results from novel explorations, the operational diagnosis (...) of dispositions, the status of aggregates of persons as social entities, and the validation of psychological tests. (shrink)