Third Edition THEORY OF KNOWLEDGE Roderick M. Chisholm Brown University This edition may be sold only in those countries to which' it is consigned by Prentice-Hall International. It is not to be re-exported and it is not for sale in the U.S.A., Mexico, or Canada. © 1989, 1977, 1966 by Prentice-Hall, Inc. A Division of Simon & Schuster Englewood Cliffs, New Jersey 07632 All rights reserved. No part of this book may be reproduced, in any form or by any means, without permission in writing from the publisher. Printed in the United States of America 10 9 8 7 6 5 4 3 2 1 ISBN D-13-^mifi5-S Prentice-Hall International (UK) Limited, London Prentice-Hall of Australia Pty. Limited, Sydney Prentice-Hall Canada Inc., Toronto Prentice-Hall Hispanoamericana, S.A., Mexico Prentice-Hall of India Private Limited, New Delhi Prentice-Hall of Japan, Inc., Tokyo Simon & Schuster Asia Pte. Ltd., Singapore Editora Prentice-Hall do Brasil, Ltda., Rio de Janeiro Prentice Hall, Englewood Cliffs, New Jersey Contents Preface vii CHAFFER 1 The Skeptic's Challenge 1 CHAFFER 2 Epistemic Justification 8 CHAFFER 3 Certainty and the Self-Presenting 18 CHAFFER 4 The A Priori 26 CHAFFER 5 The Evidence of the Senses 39 CHAPTER 6 The Transfer of Justification 49 CHAPTER 7 The Structure of Empirical Knowledge 61 CHAPTER 8 Internalism and Externalism 75 CHAPTER 9 Foundationalism and the Coherence Theory 85 CHAPTER 10 What Is Knowledge? 90 Index Foundations of Philosophy Many of the problems of philosophy are of such broad relevance to human concerns, and so complex in their ramifications, that they are, in one form or another, perennially present. Though in the course of time they yield in part to philosophical inquiry, they may need to be rethought by each age in the light of its broader scientific knowledge and deepened ethical and religious experience. Better solutions are found by more refined and rigor­ ous methods. Thus, one who approaches the study of philosophy in the hope of understanding the best of what it affords will look for both funda­ mental issues and contemporary achievements. Written by a group of distinguished philosophers, the Foundations of Philosophy Series aims to exhibit some of the main problems in the various fields of philosophy as they stand at the present stage of philosophical history. While certain fields are likely to be represented in most introductory courses in philosophy, college classes differ widely in emphasis, in method of instruction, and in rate of progress. Every instructor needs freedom to change his course as his own philosophical interests, the size and makeup of his class, and the needs of his students vary from year to year. The volumes in the Foundations of Philosophy Series—each complete in itself, but complementing the others—offer a new flexibility to the instructor, who can create his own textbook by combining several volumes as he wishes, and choose different combinations at different times. Those vol­ umes that are not used in an introductory course will be found valuable, along with other texts or collections of readings, for the more specialized upper-level courses. Elizabeth Beardsley I Monroe Beardsley I Tom L. Beauchamp Preface Since the publication in 1977 of the second edition of this book, there has been a resurgence of interest in the nature of knowledge. As a result, it is now possible to formulate the problems and proposed solutions with much greater precision than was possible ten years ago. Contemporary interest in the nature of knowledge pertains not only to that branch of philosophy called "theory of knowledge" or "epistemology," but also to the fields of information theory, artificial intelligence, and cog­ nitive science. The latter disciplines are not alternatives to the traditional theory of knowledge because they are branches of empirical science and not of philosophy. For the most part, the facts with which they are con­ cerned are not relevant to the traditional philosophical questions. Unfor­ tunately, however, this relevance has been exaggerated by many writers who do not seem to have grasped the traditional problems. I hope that the present book may help to correct this situation. Much of the recent literature on the theory of knowledge has involved a criticism of "foundationalism" and "internalism," both terms being applica­ ble to the general position set forth in the first two editions of this book. I believe that the most valuable function that can be performed by a third edition is to present, not a survey of all the conflicting views on the subject, but a defense of the traditional theory of knowledge from a "foundational" and "internal" point of view. I wish to express my indebtedness to the many people with whom I have discussed these questions. These include: (1) the members of two seminars given at Brown in 1985 and 1986, the latter attended also by students from the University of Massachusetts in Amherst; (2) the members and partici­ pants of the Summer Seminar on Theory of Knowledge, sponsored by the Council for Philosophical Studies and given at the University of Colorado Preface in Boulder in the summer of 1986; and (3) to the participants in the Colloquium on Epistemic Justification given at Brown University in November 1986. I am especially indebted to Ernest Sosa, David Bennett, John Greco, and the publisher's reader who read and criticized early versions of this material. I wish also to thank the editors and publishers of the following works for permission to reprint here certain portions of my writings: D. Reidel Pub­ lishing Company, Dordrecht, Holland, for excerpts from "An Analysis of Thirteen Epistemic Categories," from David F. Austin, ed., Philosophical Analysis: A Defence by Example," and for excerpts from "Epistemic Justifica­ tion Internally Considered," from Synthese, Vol. 38 (1988); Philosophical Perspectives, Vol. II (1988), for excerpts from "The Evidence of the Senses." CHAPTER 1 The Skeptic's Challenge THE TRADITIONAL QUESTIONS Theory of knowledge, when considered as a part of philosophy, is the concern with such questions as, "What can I know? How can I distinguish those things I am justified in believing from those things I am not justified in believing? And how can I decide whether I am more justified in believ­ ing one thing than in believing another?" These questions are properly called Socratic since they are questions about ourselves. Whatever the explanation for our interest in them may be (and providing causal explana­ tions is no part of philosophy), the fact is that the epistemological questions do arise and that those for whom they arise take them very seriously. I propose that we try to take them seriously, too. Our purpose in raising such questions is to correct and improve our own epistemic situation. Is it also that of attaining knowledge} It would be safer to say this: we want to do our best to improve our set of beliefs—to replace those that are unjustified by others that are justified and to replace those that have a lesser degree of justification with others that have a greater degree of justification. THE PHILOSOPHICAL SKEPTIC There are philosophers who doubt whether there is anything that we can know. They also doubt, therefore, whether it is possible for us to find out whether there is anything that we can know. Such philosophers—we may i 2 The Skeptic's Challenge call them "philosophical skeptics"—may thus seem to present a challenge to traditional epistemology. Should we be deterred by this challenge? The question is not whether we can refute philosophical skeptics. Nor is it even whether we can make them see that they are misguided. We are asking only whether they can provide us with reasons for thinking that we are misguided. What can they tell us? There are several possibilities. (I) They may say, "There are good reasons, after all, for supposing that we cannot know the kinds of things that most people think they can know." In support of-this contention, one could provide an impressive amount'of information about human fallibility. Suppose, then, we are given such information. Does the possession of such information mean that it is not reasonable for us to assume that we can answer our epistemological questions? If we do have information about human fallibility, that is to say, if we know something about it, then, obviously, we should take such information into account when we ask about what it is that we can know. But we should also take into account the fact that, despite the indications of fallibility, what­ ever these indications may be, we are aware of them and therefore do have information about ourselves and other people. (II) The skeptics may tell us various things about human fallibility but without professing to be justified in thinking that these things are really true. What should we say to them in this case? We may say, tautologically, that we have ground for doubting only if we have ground for doubting. But how could something we sue-not justified in believing provide us with a ground for skepticism? (III) There are the contentions of what we may call the "perhaps-you- are-wrong" skeptics. They will point out to us that Descartes' supposition of a malicious demon is logically possible. And it is true that no contradiction is involved in assuming that all my present experiences are caused by such an evil spirit. Therefore, skeptics conclude, it is not reasonsable for me to have the beliefs that I do about the things around me. A contemporary version of this reasoning has been suggested by Hilary Putnam: Imagine that a human being (you can imagine this to be yourself) has been sub­ jected to an operation by an evil scientist.