Michael Dietrich

This dissertation is concerned with historical and philosophical issues pertaining to the classical/balance controversy and the neutralist/selectionist controversy in population genetics. Historically, the nature of the connection between these controversies is critically examined with special attention to the claim that the neutralist position is actually the classical position brought up to date. This account of the origins of the neutral theory provides the context for examining the decision to pursue the neutral theory. The pursuit-worthiness of the neutral theory and of scientific theories in general are analyzed as practical decisions, as opposed to strictly epistemic or pragmatic decisions. The role of epistemic factors in scientific judgements is examined further in light of the Duhem-Quine thesis. The holism associated with the Duhem-Quine thesis is reinterpreted in a Duhemian fashion which is sensitive to scientific practice. Similarly, the underdetermination associated with the Duhem-Quine thesis is further articulated and refined such that claims of underdetermination are specified. Specified underdetermination clearly delimits the extent of underdetermination on a case by case basis and so provides a means for adjudicating between philosophers' and sociologists' claims about the extent of underdetermination and the importance of epistemic factors in scientific judgements.

Using an analogy between moths and men, in 1916, Richard Goldschmidt proposed that homosexuality was a case of genetic intersexuality. As he strove to create a unified theory of sex determination that would encompass animals ranging from moths to men, Goldschmidt's doubts grew concerning the association of homosexuality with intersexuality until, in 1931, he dropped homosexuality from his theory of intersexuality. Despite Goldschmidt's explicit rejection of his theory of homosexuality, Theo Lang, a researcher in the Genealogical-Demographic Department of the Institute for Psychiatric Research in Munich, revived it, maintained Goldschmidt's association with it, and argued on its behalf in publications from 1936 to 1960. Lang's appropriation of Goldschmidt's theory did not depend on his resolution of the difficulties Goldschmidt had found with his own theory. Lang and Goldschmidt, I argue, had fundamentally different scientific and social commitments that allowed one to reject this theory of homosexuality and the other to accept it