The set of English modal verbs is widely recognized to communicate two broad clusters of meanings: epistemic and root modal meanings. A number of researchers have claimed that root meanings are acquired earlier than epistemic ones; this claim has subsequently been employed in the linguistics literature as an argument for the position that English modal verbs are polysemous (Sweetser, 1990). In this paper I offer an alternative explanation for the later emergence of epistemic interpretations by linking them to the development of the child's theory of mind (Wellman, 1990); if correct, this hypothesis might have important implications for the shape of the semantics of modal verbs.

This paper was originally written while the author was at the University of California at Berkeley

It is widely assumed in the developmental literature that certain classes of modal expression appear later in language acquisition than others; specifically, epistemic interpretations lag behind non-epistemic (or root) interpretations. An explanation for these findings is proposed in terms of the child's developing theory of mind, i.e. the ability to attribute to oneself and others mental representations, and to reason inferentially about them. It is hypothesized that epistemic modality crucially implicates theory-of-mind abilities and is therefore expected to depend on prior developments in the child's ability to handle representations of mental representations. In support of this hypothesis, it is shown that autistic individuals (who arguably possess a deficient theory-of-mind mechanism) have difficulty with epistemics.

The set of English modal verbs is widely recognised to communicate two broad clusters of meanings: epistemic and root modal meanings. A number of researchers have claimed that root meanings are acquired earlier than epistemic ones; this claim has subsequently been employed in the linguistics literature as an argument for the position that English modal verbs are polysemous (Sweetser 1990). In this paper I offer an alternative explanation for the later emergence of epistemic interpretations by liniking them to the development of the child's theory of mind (Wellman 1990). If correct, this hypothesis might have important implications for the shape of the semantics of modal verbs.