Abstract

The central objective of this dissertation is to undermine and develop an alternative to the standard, micro-essentialist, account of natural kinds, according to which natural kinds are invariably defined by intrinsic, microstructural essences. My argument to this effect partly consists in showing that chemical compounds and biological species, which micro-essentialists typically consider to be paradigmatic examples of natural kinds, do not satisfy their own criteria for naturalness, since membership in them does not hinge on exhibiting exclusive sets of intrinsic, microstructural properties. In light of this and other considerations, I urge that we instead conceive natural kinds more broadly as causally relevant kinds, that is, as kinds that figure as the subjects of causal laws. By contrast to what the micro-essentialist conception of natural kinds suggests, I show that causally relevant kinds may in some cases have relational or macroscopic properties as essences. I provide evidence for this view by undermining some of the assumptions that lend support to its denial, namely the assumption that things always enter into the causal relations they enter into by virtue of their intrinsic, microstructural, properties, and the assumption that generalizations must have unlimited scope and be exceptionless to count as laws of nature. I argue that things sometimes possess causal powers by virtue of their relational and macroscopic properties, and that some of the generalizations of the special sciences constitute laws even if they are exception-ridden and have only limited scope. I thus give credence to the idea that at least some of the relationally and macroscopically defined kinds that fall within the domain of the special sciences figure in causal laws and accordingly deserve to be deemed natural