Date of Award


Degree Name

Doctor of Philosophy (PhD)

Schools and Centres

Philosophy and Theology

First Supervisor

Professor Ian E. Thompson


This thesis explores the relation in Peirce’s philosophy between his theory of categories and his pragmatism. My most central claim is that the possibility and validity of metaphysics as a philosophical science depend on the appropriateness of its method. I argue that an appropriate method for metaphysics is possible, and that in Peirce’s pragmatism as founded on his theory of categories we find such a method. In developing this thesis I seek to demonstrate four key propositions: 1. Peirce’s ‘pragmatism’ is fundamentally a form of metaphysical and epistemological realism and in this respect differs from logical positivism and other types of pragmatism that are overtly anti-metaphysical and skeptical about the possibility of our knowledge of real generals. 2. Peirce’s ‘theory of categories’ is the key to understanding his philosophy and demonstrates the extent to which he embraces a form of dialectical realism that bears striking resemblance to certain forms of scholastic metaphysics. 3. Peirce’s ‘semiotic’ or theory of signs can only be properly understood if we take full account of his theory of categories and the form of metaphysical and epistemological realism it implies. 4. Peirce’s account of semiotic is based on an irreducible trichotomy that he holds to exist between the categories, and which is reflected in the triadic relationship between Sign, Sign User and Thing Signified. The apparent inconsistencies and indecisiveness in Peirce’s account of his ‘pragmatism’ can be explained if we recognise that he takes the four propositions outlined above for granted. Because he takes these propositions for granted as virtually self-evident, he fails to make fully explicit the internal logical connections between them and the different parts of his system. Despite appearances to the contrary, I maintain Peirce is a coherent and systematic thinker. Based on the evidence drawn from reviewing the literature, and arguing the case in defence of these propositions, I propose to set out my argument in the following chapters, and the summary of the contents of each should make explicit the structure and content of my overall argument and conclusions.

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