Metaphor is a pervasive and significant feature of language. We use metaphor to talk about the world in familiar and innovative ways, and in contexts ranging from everyday conversation to literature and scientific theorizing. However, metaphor poses serious challenges for standard philosophical theories of meaning, because it straddles so many important boundaries: between language and thought, between semantics and pragmatics, between rational communication and mere causal association. ;In this dissertation, I develop a pragmatic theory of metaphorical utterances which reconciles two (...) apparently incompatible intuitions. The first is that metaphors are vehicles for undertaking speech acts with a propositional content distinct from their conventional sentence meaning. The second is that metaphors are tools for inducing the essentially non-propositional effect of 'seeing things in a new light' or under a new aspect. These intuitions seem to be incompatible because it is assumed that only one can capture the essential function of metaphor. I propose instead that non-propositional 'seeing-as' or aspectual thought serves as the means by which speakers intend to accomplish their end of communicating content. This does not imply that speakers are not interested in and even committed to the effects of aspectual thought as well, only that it is not their sole, ultimate intention. ;In order to substantiate this proposal about how metaphor works, I develop an account of the psychological structures on which aspectual thought operates and the changes it engenders; I then show how the content of the speaker's intended speech act is determined by the aspect the sentence generates. By bringing propositional content and non-propositional aspectual thought together in this way, my account can treat the full range of metaphors, from 'ordinary' to 'poetic', within a unified theory. Armed with this account, we have the explanatory resources necessary to acknowledge both that ordinary conversational metaphors are efficient and sometimes essential vehicles for communicating determinate propositional contents, and also that rich, poetic metaphors are invitations to an open-ended contemplation of the subject under discussion. These apparently very different effects turn out to be manifestations of the same basic process of comprehension. (shrink)