Vincent F. Hendricks: Professor, Director | Center for Information and Bubble Studies | University of Copenhagen

Knowledge and Belief

Knowledge and Belief

An Introduction to the Logic of the Two Notions

Jaakko Hintikka
Prepared by
Vincent F. Hendricks
John Symons
King’s College Publications, 2005

Abstract | Blurbs | Cover


In 1962 Jaakko Hintikka published Knowledge and Belief – An Introduction to the Logic of the Two Notions with Cornell University Press. There has hardly been a paper or a book on epistemic and doxastic logic since not referring to this seminal treatise. Although everybody in logic, mainstream and formal epistemology, game-theory, economics, computer science and social software refer to the book it is very likely that a great many have never literally had their hands on it as it went out of print in the late 1960’s (second printing in 1964, third printing in 1967 and fourth printing in 1969). It is our pleasure to provide the interdisciplinary community of logicians, epistemologists, game-theorists, computer scientists and other interested parties, with this new edition of Knowledge and Belief.

This edition has not been revised, only extended. There are two with each other related reasons for the extended version. Firstly, albeit it is generally acknowledged that Jaakko Hintikka is one of the founding fathers of epistemic and doxastic logic, his fundamental epistemological ambition with developing these logics has generally been neglected by formal and mainstream epistemologists alike. Thus, the current edition has been extended with a separate introductory chapter showing how Hintikka from the outset has been engaged in a dialectic movement between epistemology and logic. Secondly, his movement has been going on for more than 40 years so this edition includes some of Hintikka’s latest papers on the subject.


This is book is the point of departure not only of contemporary epistemic logic but also of some of the best philosophical reflection about it and about the epistemological problems that motivate it. The book has aged gracefully and it remains today not only a model of how to do philosophical logic but also a self-contained presentation of epistemic logic equally useful for experts and for students. Briefly the book is a masterpiece, which not only inaugurates a logical discipline but that also nicely prefigures some of its main foundational themes.  Its re-edition istherefore timely and I am sure it will be well received, not only by philosophers and logicians, but also by the many communities where epistemic logic has left its mark in recent years (from computer science to mathematical economics)
Horacio Arló-Costa, Carnegie Mellon University

Knowledge and Belief is a classic on which a generation – my generation – of epistemologists cut their teeth. This reissue is welcome. It will provide something for the next generation to chew on.
Fred DretskeDuke University

It is wonderful to see this classic being reissued after so many years out of print.  It was extremely influential in its day; its influence continues to this day, through the impact of epistemic logic in fields as diverse distributed computing, artificial intelligence, and game theory.  This reissue should make it possible for a new generation of researchers to appreciate Hintikka’s pathbreaking work.
Joseph Halpern, Cornell University

It is not an exaggeration to say that the publication of Jaakko Hintikka’s Knowledge and Belief in 1962 launched a new branch of philosophical logic, epistemic logic. In this seminal work Hintikka developed a theory of epistemic-doxastic modalities and applied it to the characterization of the concepts of knowledge, belief, certainty, and related notions. It has generated an extensive literature and engendered both foundational discussions and formal developments in epistemology, for example, the logic of perception and perceptual knowledge, the epistemology of reference, and a theory of questions and inquiry. This new edition of Knowledge and Belief includes chapters which discuss the recent developments in the field, including Hintikka’s “second generation epistemic logic”. This book is invaluable to all students of epistemology.
Risto Hilpinen, University of Miami

Jaakko Hintikka’s Knowledge and Belief : An Introduction to the Logic of the Two notions was described in Hector Neri Castaneda’s  review as “probably the single most important contribution to philosophical technology since C.I.Lewis’s invention of the system of strict implication”. The subsequent developments of research inspired by Hintikka’s book in logic and in many other disciplines corroborate Castaneda’s statement.
Paul Gochet, University of Liège

Knowledge and Belief was a landmark in the history of epistemology, having brought, for the first time, the sharp gaze of logic to questions that have occupied humanity for thousands of years.  The book contributed to making modal logic a major tool in philosophical logic.  It was also amazingly prescient, having preceded by more than a decade the explosion of interest in epistemic logic outside of philosophy, in computer science, economics, and linguistics. The republication of such a classic is to be celebrated.
Moshe Vardi, Rice University