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Hardcover | Out of Print | 344 pp. | 6 x 9 in | July 2006 | ISBN: 9780262083492
Paperback | $25.00 Short | £19.95 | 344 pp. | 6 x 9 in | January 2009 | ISBN: 9780262512510
eBook | $18.00 Short | January 2009 | ISBN: 9780262252133
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Rationality and Logic


In Rationality and Logic, Robert Hanna argues that logic is intrinsically psychological and that human psychology is intrinsically logical. He claims that logic is cognitively constructed by rational animals (including humans) and that rational animals are essentially logical animals. In order to do so, he defends the broadly Kantian thesis that all (and only) rational animals possess an innate cognitive "logic faculty." Hanna's claims challenge the conventional philosophical wisdom that sees logic as a fully formal or "topic-neutral" science irreconcilably separate from the species- or individual-specific focus of empirical psychology.Logic and psychology went their separate ways after attacks by Frege and Husserl on logical psychologism--the explanatory reduction of logic to empirical psychology. Hanna argues, however, that--despite the fact that logical psychologism is false--there is an essential link between logic and psychology. Rational human animals constitute the basic class of cognizers or thinkers studied by cognitive psychology; given the connection between rationality and logic that Hanna claims, it follows that the nature of logic is significantly revealed to us by cognitive psychology. Hanna's proposed "logical cognitivism" has two important consequences: the recognition by logically oriented philosophers that psychologists are their colleagues in the metadiscipline of cognitive science; and radical changes in cognitive science itself. Cognitive science, Hanna argues, is not at bottom a natural science; it is both an objective or truth-oriented science and a normative human science, as is logic itself.

About the Author

Robert Hanna is Professor of Philosophy at the University of Colorado at Boulder. He is the author of Kant and the Foundations of Analytical Philosophy.


“A densely-argued and ambitious defense of a ‘broadly Kantian theory of human rationality and logic.’”—The Review of Metaphysics
“An admirable and promising attempt to confront the question of the nature of logic and its relation to rationality in a substantive and open-minded manner, without excessive reliance on intuition or gut feeling, without hand waving, without begging questions, and in a creative and intellectually stimulating way. This book is highly recommended to philosophers, logicians, and cognitive psychologists.”—Notre Dame Philosophical Reviews
“Logic and Rationality is an important contribution to a debate that has been ignored for too long. Students and researchers who have thought that Frege’s and Husserl’s dismissal of logical psychologism was decisive should not ignore Hanna’s compelling argument for logical cognitivism. Hanna’s very impressive work deserves to be studied intently by those with an interest in the often criticized but largely overlooked relationship between logic and psychology.”—Polish Journal of Philosophy


“Hanna suggests that we human beings are rational in the sense that we have an innate grasp of the concepts needed for appraising the cogency of our own thinking. Starting from this idea, he steers an ingenious way between psychologism and Platonism, and argues persuasively for a neo-Kantian view of the nature of logic and our engagement with it. This stimulating and wide-ranging book will be of interest to philosophers of logic and also to cognitive psychologists.”
Professor Jane Heal, University of Cambridge