Sober (1992) has recently evaluated Brandon's (1982, 1990; see also 1985, 1988) use of Salmon's (1971) concept of screening-off in the philosophy of biology. He critiques three particular issues, each of which will be considered in this discussion.

Treating species as individuals and not classes has been crucial to the integration of evolutionary theory with modern systematics. Despite the theoretically important role the concept of individuality plays in modern phylogenetic systematics and in evolutionary theory more generally, many have been content to rely on common-sense intuitions about what counts as an individual. One of the most often cited intuitions is that individuals should be defined intrinsically. Unfortunately, common-sense intuitions like this one have proven to be inadequate for identifying (...) and characterizing historical individuals (like species). An examination of real-world biological examples shows that our common-sense intuitions are equally inadequate when applied to at least some biological organisms--the paradigm individuals. (shrink)

While most researchers who use evolutionary theory to investigatehuman nature especially human sexuality describe themselves as ``interactionists'', there is no clear consensus on the meaning of thisterm in this context. By interactionism most people in the fieldmean something like, both nature and nurture ``count'' in thedevelopment of human psychology and behavior. Nevertheless, themultidisciplinary nature of evolutionary psychology results in a widevariety of interpretations of this general claim. Today, mostdebates within evolutionary psychology about the innateness of agiven behavioral characteristic or over (...) its development turn as muchon which conception of ``innateness'' and ``interactionism'' theresearcher holds as on any empirical data they might derive. (shrink)

Over the past several years, various operational definitions of gender have been used in studies of gender conformity in homosexual males. The goal of these studies is to demonstrate that childhood gender nonconformity (CGN) is either the proximate cause of adult homosexuality or an intermediate step in a biologically mediated process. The hypothesis of a causal connection between the development of gender and sexual orientation is embedded within the context of a biological (evolutionary) understanding of human behavior. Thus, testing the (...) hypothesis of a causal connection between CGN and sexuality requires a concept of gender that is compatible with the basic principles of biological causation and our current understanding of evolutionary processes. I will argue that the concepts of gender used in the attempt to demonstrate a causal connection between CGN and sexual orientation are inappropriate because they provide no uniform, consistent method for identifying and measuring the biologically significant components of gender. I will also argue that the concept of gender that does emerge from these studies suggests an hypothesis about the connection between sexuality and gender that is not consistent with the cross-gendered theory of the etiology of homosexuality. (shrink)

Species serve as both the basic units of macroevolutionary studies and as the basic units of taxonomic classification. In this paper I argue that the taxa identified as species by the Phylogenetic Species Concept (Mishler and Brandon 1987) are the units of biological organization most causally relevant to the evolutionary process but that such units exist at multiple levels within the hierarchy of any phylogenetic lineage. The PSC gives us no way of identifying one of these levels as the privileged (...) level on which taxonomic classifications can be based. (shrink)