Electronic Thesis and Dissertation Repository

Thesis Format

Monograph

Degree

Doctor of Philosophy

Program

Philosophy

Supervisor

Robert J. Stainton

Abstract

Most words in natural languages are polysemous, that is they have related but different meanings in different contexts. These polysemous meanings (senses) are marked by their structuredness, flexibility, productivity, and regularity. Previous theories have focused on some of these features but not all of them together. Thus, I propose a new theory of polysemy, which has two components. First, word meaning is actively modulated by broad contexts in a continuous fashion. Second, clustering arises from contextual modulations of a word and is then entrenched in our long term memory to facilitate future production and processing. Hence, polysemous senses are entrenched clusters in contextual modulation of word meaning and a word is polysemous if and only if it has entrenched clustering in its contextual modulation. I argue that this theory explains all the features of polysemous senses. In order to demonstrate more thoroughly how clusters emerge from meaning modulation during processing and provide evidence for this new theory, I implement the theory by training a recurrent neural network (RNN) that learns distributional information through exposure to a large corpus of English. Clusters of contextually modulated meanings emerge from how the model processes individual words in sentences. This trained model is validated against a human-annotated corpus of polysemy, focusing on the gradedness and flexibility of polysemous sense individuation, a human-annotated corpus of regular polysemy, focusing on the regularity of polysemy, and behavioral findings of offline sense relatedness ratings and online sentence processing. Last, the implication to philosophy of this new theory of polysemy is discussed. I focus on the debate between semantic minimalism and semantic contextualism. I argue that the phenomenon of polysemy poses a severe challenge to semantic minimalism. No solution is foreseeable if the minimalist thesis is kept, and the existence of contextual modulation is denied within the literal truth condition of an utterance.

Summary for Lay Audience

Some words have more than one related meanings. For example, “lock” can mean a mechanism to fasten something or a confined section of waterway, and these two meanings are related to the concept of restriction. This phenomenon is called polysemy. Polysemy has some interesting features. For example, some meanings of polysemous words are more regular, such as the two meanings of “lock” mentioned above, but some meanings are less prototypical but still connect with the core regular meaning, such as the technique — “lock” of limbs in wrestling. Furthermore, new meanings can be created as time goes, such as a digital “lock” in the form of a computer program. I propose a theory of polysemy to explain what polysemy is and why it has these features. I draw my theory from two characteristics of language. First, contexts of language use often change and contribute new information to the meaning of a word in use. Second, some contextual uses of language are similar and frequent so they are strengthened in our memory to ease future use. Polysemy, in my theory, is the collection of strengthened contextual meanings, or more formally, entrenched clusters of contextual meaning modulations. In this dissertation, I compare my theory with other theories of polysemy, demonstrate how my theory of polysemy could explain the features of polysemy better. I also implement my theory in a computational model and verify it with annotated corpus and behavioral findings to collect evidence for my theory. Last, I discuss the implication of my new theory of polysemy to philosophy of language.

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