Book excerpt: Epistemic logic is the branch of philosophical thought that seeks to formalize the discourse about knowledge. Its object is to articulate and clarify the general principles of reasoning about claims to and attributions of knowledge. This comprehensive survey of the topic offers the first systematic account of the subject as it has developed in the journal literature over recent decades. Rescher gives an overview of the discipline by setting out the general principles for reasoning about such matters as propositional knowledge and interrogative knowledge. Aimed at graduate students and specialists, Epistemic Logic elucidates both Rescher's pragmatic view of knowledge and the field in general.