This book offers a critical reconstruction of the fundamental ideas and methods of artificial intelligence research. Through close attention to the metaphors of AI and their consequences for the field's patterns of success and failure, it argues for a reorientation of the field away from thought in the head and toward activity in the world. By considering computational ideas in a philosophical framework, the author eases critical dialogue between technology and the humanities and social sciences. AI can benefit from new understandings of human na- ture, and in return, it offers a powerful mode of investigation into the practicalities and consequences of physical realization. Computation and human experience Learning in doing: Social, cognitive, and computational perspectives GENERAL EDITORS: ROY PEA JOHN SEELY BROWN Sociocultural Psychology: Theory and Practice of Doing and Knowing, edited by Laura M. W. Martin, Katherine Nelson, and Ethel Tobach Sociocultural Studies of Mind, edited by James V. Wertsch, Pablo del Rio, and Amelia Alvarez The Computer as Medium, edited by Peter Bogh Andersen, Berit Holmqvist, and Jens F. Jensen Distributed Cognitions: Psychological and Educational Considerations, edited by Gavriel Salomon Understanding Practice: Perspectives on Activity and Context, edited by Seth Chaiklin and Jean Lave Street Mathematics and School Mathematics, by Terezinha Nunes, David William Carraher, and Analucia Dias Schliemann Situated Learning: Legitimate Peripheral Participation, by Jean Lave and Etienne Wenger The Construction Zone: Working for Cognitive Change in School, by Denis Newman, Peg Griffin, and Michael Cole Plans and Situated Actions: The Problem of Human Machine Communication, by Lucy A. Suchman Mind and Social Activity, edited by Ethel Tobach, Rachel Joffe Falmagne, Mary B. Parlee, Laura Martin, and Aggie Schribner Kapelman Computation and human experience PHILIP E. AGRE University of California, San Diego CAMBRIDGE UNIVERSITY PRESS CAMBRIDGE UNIVERSITY PRESS Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, Sao Paulo Cambridge University Press The Edinburgh Building, Cambridge CB2 2RU, UK Published in the United States of America by Cambridge University Press, New York www. Cambridge. org Information on this title: www.cambridge.org/9780521384322 © Cambridge University Press 1997 This publication is in copyright. Subject to statutory exception and to the provisions of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press. First published 1997 A catalogue record for this publication is available from the British Library Library of Congress Cataloguing in Publication data Agre, Philip E. Computation and human experience / Philip E. Agre. p. cm. - (Learning in doing) ISBN 0-521-38432-X (hardback). -ISBN 0-521-38603-9 (pbk.) 1. Artificial Intelligence — Data processing. 2. Human behavior. I. Title. II. Series. Q336.A37 1997 006.3 '01 -dc20 96-14826 CIP ISBN-13 978-0-521-38432-2 hardback ISBN-10 0-521-38432-X hardback ISBN-13 978-0-521-38603-6 paperback ISBN-10 0-521-38603-9 paperback Transferred to digital printing 2006 Joshu asked Nansen: "What is the path?" Nansen said: "Everyday life is the path." Joshu asked: "Can it be studied?" Nansen said: "If you try to study, you will be far away from it." Joshu asked: "If I do not study, how can I know it is the path?" Nansen said: "The path does not belong to the perception world, neither does it belong to the nonperception world. Cognition is a delusion and noncognition is senseless. If you want to reach the true path beyond doubt, place yourself in the same freedom as sky. You name it neither good nor not-good." At these words Joshu was enlightened. Mumons comment: Nansen could melt Joshu's frozen doubts at once when Joshu asked his questions. I doubt though if Joshu reached the point that Nansen did. He needed thirty more years of study. In spring, hundreds of flowers; in autumn, a harvest moon; In summer, a refreshing breeze; in winter, snow will accompany you. If useless things do not hang in your mind, Any season is a good season for you. Ekai, The Gateless Gate, 1228 Contents Preface page xi 1 Introduction 1 Activity 1 Planning 5 Why build things? 10 How computation explains 16 Critical orientation 20 Outline 24 2 Metaphor in practice 27 Levels of analysis 27 Language in practice 28 Metaphors in technical work 33 Centers and margins 38 Margins in practice 44 3 Machinery and dynamics 49 Mentalism 49 Inter actionism 52 Machinery and dynamics 57 Interactionist methodology 61 4 Abstraction and implementation 66 Structures of computation 66 A case study: variables 71 vii viii Contents Architectural and generative reasoning 80 Generative reasoning and mentalism 85 5 The digital abstraction 89 Digital logic 89 The meaning of circuitry 92 The temporality of computation 96 Embodied computation 103 6 Dependency maintenance 105 Critical technical practice 105 About routines 107 Main ideas of dependency maintenance 113 7 Rule system 124 Using dependencies in a rule system 124 Rule language semantics 126 How it works 130 Incremental updating 136 Advanced rule writing 139 8 Planning and improvisation 142 The idea of planning 142 Troubles with planning 145 Planning and execution 150 Improvisation 156 9 Running arguments 160 From plans to arguments 160 Argument and centralization 166 How running arguments work 171 10 Experiments with running arguments 179 Motivation 179 Demonstration 181 Patterns of transfer 191