In this book Saul Kripke brings his powerful philosophical intelligence to bear on Wittgenstein's analysis of the notion of following a rule.

The paper asks under what conditions deductive reasoning transmits justification from its premises to its conclusion. It argues that both standard externalist and standard internalist accounts of this phenomenon fail. The nature of this failure is taken to indicate the way forward: basic forms of deductive reasoning must justify by being instances of 'blind but blameless' reasoning. Finally, the paper explores the suggestion that an inferentialist account of the logical constants can help explain how such reasoning is possible.

This volume presents a series of influential essays by Paul Boghossian on the theory of content and on its relation to the phenomenon of a priori knowledge. The essays are organized under four headings: the nature of content; content and self-knowledge; knowledge, content, and the a priori; and colour concepts.