Externalism and a posteriori semantics

Abstract

It is widely held that the meaning of certain types of terms, such as natural kind terms, is individuated externalistically, in terms of the individual’s external environment. Recently a more radical thesis has emerged, a thesis we dub ‘a posteriori semantics.’ The suggestion is that not only does a term’s meaning depend on the external environment, but so does its semantics. One motivation for this is the aim to account for cases where a putative natural kind term fails to pick out a natural kind: The term may have a standard externalist semantics (if it picks out a natural kind) or a more descriptivist one (if it does not). Knowing which semantics applies will therefore require detailed empirical knowledge. This move has also been employed in cases where a singular term, such as a name, fails to have a reference. We argue that a posteriori semantics is inherently implausible, since the type of semantics common terms should be given ought not to be conditional on details of chemistry or physics. A number of difficulties for the position—‘metaphysical,’ epistemological, and methodological—are articulated. Finally, we suggest that a posteriori semantics misconstrues the way in which semantics is empirical.