Abstract
Drawing on diverse historical cases, this paper describes and examines various aspects of a modality of scientific appraisal which has remained largely unexplored, theory pursuit. Specifically, it addresses the following issues: the epistemic and pragmatic commitments involved in theory pursuit, including how these differ from those characteristic of theory acceptance; how the research interests of scientists enter into their pursuit decisions; some of the strategies for the refinement and extension of a theory's empirical abilities which typify theory pursuit; and the need to distinguish between individual and community rationality in contexts of pursuit.