Abstract

This paper investigates the interaction between semantic theories for cp-laws (roughly, laws that hold “all things equal”) and metaphysical theories of kinds in the special sciences. Its central conclusion is that cp-laws concerning kinds behave differently from cp-laws concerning non-kinds: “ravens are black” which concerns the kind corvus corax, behaves differently from from “albino ravens are white” which concerns the non-kind grouping of albino ravens. I argue that this difference is in the first instance logical: the two sorts of cp-laws give rise to different inferential patterns. I draw two further conclusions. The difference in logical behavior poses a severe problem for extant semantic theories of cp-laws, and: we cannot elucidate the distinction between kinds and non-kinds by suggesting that only kinds can appear in laws