Empirical lessons for philosophical theories of mental content
This thesis concerns the content of mental representations. It draws lessons for philosophical theories of content from some empirical findings about brains and behaviour drawn from experimental psychology (cognitive, developmental, comparative), cognitive neuroscience and cognitive science (computational modelling). Chapter 1 motivates a naturalist and realist approach to mental representation. Chapter 2 sets out and defends a theory of content for static feedforward connectionist networks, and explains how the theory can be extended to other supervised networks. The theory takes forward Churchland’s state space semantics by making a new and clearer proposal about the syntax of connectionist networks − one which nicely accounts for representational development. Chapter 3 argues that the same theoretical approach can be extended to unsupervised connectionist networks, and to some of the representational systems found in real brains. The approach can also show why connectionist systems sometimes show typicality effects, explaining them without relying upon prototype structure. That is discussed in chapter 4, which also argues that prototype structure, where it does exist, does not determine content. The thesis goes on to defend some unorthodox features of the foregoing theory: that a role is assigned to external samples in specifying syntax, that both inputs to and outputs from the system have a role in determining content, and that the content of a representation is partly determined by the circumstances in which it developed. Each, it is argued, may also be a fruitful way of thinking about mental content more generally. Reliance on developmental factors prompts a swampman-type objection. This is rebutted by reference to three possible reasons why content is attributed at all. Two of these motivations support the idea that content is partly determined by historical factors, and the third is consistent with it. The result: some empirical lessons for philosophical theories of mental content.