Abstract: Charles Peirce's pragmatist philosophy contains important ideas for understanding the nature of epistemic rationality and rational self-control. After a discussion of his views about the different demands of theory and practice, the book explains his account of truth, before comparing it with the correspondence theory of truth and tracing its relations to his theory of indexical reference. This is followed by an investigation of his defence of a system of ‘scientific metaphysics’ and its role in rational inquiry. We then turn to a consideration of how his pragmatism and his account of rationality rest upon his acceptance of a modified version of the common-sense philosophy. This theme in his thought leads him to emphasize the role of sentiments and emotions in epistemic evaluation, and this lies behind his distinctive views about doubt and about why we should not take scepticism seriously. The final two chapters of the book explore Peirce's argument for the reality of God and begin to address the question of how he thought his pragmatist philosophy could be proved.

Keywords: common sense, doubt, God, Peirce, pragmatism, rationality, reference, scientific metaphysics, truth