What kinds of things are there in the world? How should scientific concepts and classifications be formulated, so that they reliably support inference and manipulation of phenomena? In philosophy, principles of scientific classification have mainly been discussed in terms of theories of natural kinds. It is questionable, however, whether these theories can adequately describe the foundations of social-scientific classification: The social and behavioral sciences do not study unchanging structures of reality, and classifications are often associated with governmental purposes. Classifications are often normatively loaded (e.g. psychiatric categories), and hence they do not only describe their targets, but can often influence their identity and behavior.
Building on philosophy-of-science discussions on mechanisms, extrapolation, and boundary concepts, the project develops a novel, scientifically applicable theory of the nature and the inferential roles of social-science classifications.