Argues that the regularity theory of causation, which underlies traditional conceptions of validity, is inadequate for describing and explaining many causal inferences made in professional practice and everyday life. Advocates an expanded, pluralistic conception of validity that allows for the validity of inferences made in a variety of ways. (FMW)

Discusses the differentiation of the American professoriate on the following primary dimensions of professionalism: (1) patterns of work; (2) identification; (3) authority; (4) career; and (5) association. Argues that integration is accomplished through overlap of subcommunities, rather than through socialization or similar functions. (FMW)