Structuring Thought: Concepts, Computational Syntax, and Cognitive Explanation

The topic of this dissertation is what thought must be like in order for the laws and generalizations of psychology to be true. I address a number of contemporary problems in the philosophy of mind concerning the nature and structure of concepts and the ontological status of mental content. Drawing on empirical work in psychology, I develop a number of new conceptual tools for theorizing about concepts, including a counterpart model of concepts\u27 role in linguistic communication, and a deflationary theory of concepts\u27 formal features. I also suggest some new answers to old problems, arguing, for example, that content realism is not hostage to a naturalized semantics. This dissertation can, as a whole, be read as a sympathetic re-evaluation of the language of thought hypothesis (LOT). LOT claims that thoughts are sentences in a mental language of computation, and are composed of meaningful, atomic symbols—concepts—which are individuated entirely by their formal features. Each chapter either defends various components of LOT from recent criticism, or fills in gaps in the theory. I begin the dissertation by introducing the language of thought project, and motivating and explaining each of its central components. In chapter 2, I discuss a recent competitor to atomism—neo-empiricism—and argue that it fails to meet several key desiderata on theories of concepts, and defend atomism from similar charges. In chapter 3, I argue against a view common to both philosophy and psychology: that concepts must be shareable. If true, atomism is in jeopardy. I find shareability to be unmotivated, and suggest an alternative counterpart model of concepts that does a better job of explaining the things shareability was supposed to explain. Chapter 4 takes up the question of what formal features are and how mental symbols are individuated. I develop a reductive account, arguing that formal features are certain sorts of physical properties and symbol types are sets of these properties. I turn to the topic of content in chapter 5, and defend a very strong version of content realism against recent criticism