REASONING AND THINKING Reasoning and Thinking Ken Manktelow University of Wolverhampton, UK Copyright © 1999 by Psychology Press Ltd. a member of the Taylor & Francis group. All rights reserved. No part of this book may be reproduced in any form by photostat, microform, retrieval system, or any other means without the prior written permission of the publisher. http://www.psypress.co.uk/ Psychology Press Ltd 27 Church Road Hove East Sussex, BN3 2FA UK This edition published in the Taylor & Francis e-Library, 2005. “To purchase your own copy of this or any of Taylor & Francis or Routledge’s collection of thousands of eBooks please go to http://www.ebookstore.tandf.co.uk/.” British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library Library of Congress Cataloging-in-Publication Data are available ISBN 0-203-01556-8 Master e-book ISBN ISBN 0-86377-708-2 (hbk) ISBN 0-86377-709-0 (pbk) ISSN 1368-4558 Front cover illustration: Indecision, oil painting by Andrea Landini (1847–c.1911). Reproduced by permission of Plymouth City Museums and Art Gallery. In memory of John Bennett, who first taught me psychology Contents Series Preface vii Acknowledgements viii 1. Reasoning and thinking: A four-way introduction 1 2. Deduction: Experiments with syllogisms 11 3. Deduction: Experiments with “if” and other 33 connectives 4. Deduction: Biases and content effects 54 5. Theories of deduction 80 6. Hypothesis testing 101 7. Induction 118 8. Judging probability 138 9. Decision making 159 10. Reasoning, thinking, and rationality 181 References 194 Author index 209 Subject index 218 Series Preface Cognitive Psychology: A Modular Course, edited by Gerry Altmann and Susan E.Gathercole, aims to provide undergraduates with stimulating, readable, affordable brief texts by leading experts. Together with three other modular series, these texts will cover all the major topics studied at undergraduate level in psychology. The companion series are: Clinical Psychology, edited by Chris Brewin; Developmental Psychology, edited by Peter Bryant and George Butterworth; and Social Psychology, edited by Miles Hewstone. The series will appeal to those who want to go deeper into the subject than the traditional textbook will allow, and base their examination answers, research, projects, assignments, or practical decisions on a clearer and more rounded appreciation of the research evidence. Other titles in this series: Essentials of Human Memory Alan D.Baddeley Laboratory Psychology Julia Nunn (Ed.) Imagery John T.E.Richardson Acknowledgements Anyone who does research builds up a huge store of debts and thanks. It is difficult to do justice to my own list, so rather than try to include everyone, and risk missing somebody out, I shall just pick out the three people who have been my main inspiration in the work I have done over more years than I will admit to in public: Jonathan Evans, David Over, and Peter Wason. I have been pretty lucky with research students too, especially Neil Fairley, Steve Kilpatrick, Tom Ormerod, and Ed Sutherland. Thanks also to all the other psychologists from round the world with whom I have exchanged ideas, papers, and drinks bills. I would also like to express my gratitude to the people I work with at Wolves, particularly Ann Henshaw and Kevin Hogan, for their constant support through both good and less good times. The manuscript of this book was read and commented on by Roger Dominowski, Neil Fairley, David Hardman, Linda Miller, Mike Oaksford, David Over, and Fred Vallée- Tourangeau, and I am grateful for the trouble they took over this. You should be too: they are responsible for the improvements on the raw material. Rachel Windwood and, latterly, Linda Jarrett, at the publishers, were also very helpful in dealing with my queries and excuses. Finally, my special thanks go to Linda Miller. K.I.MANKTELOW 1 Reasoning and thinking: A four-way introduction The psychological study of thinking has both a very long and a very short history. Its long aspect comes from its antecedents in philosophy, where ideas can be traced back to classical antiquity: Aristotle, in particular, casts a shadow stretching over more than 2000 years. On the other hand, the psychology of human thinking, as a branch of cognitive psychology, can hardly be older than cognitive psychology itself, and the birthday of the latter is often located in the late 1950s (see e.g. Baars, 1996). In fact, we can look to even more recent times for the beginnings of a true cognitive psychology of thinking, to Wason and Johnson-Laird’s Psychology of Reasoning: Structure and Content, published in 1972. Thought and reason are, of course, foremost among the list of properties that we often invoke when we try to mark out what makes us different from other animals. Making inferences is also a fundamental requirement of intelligence, so you might expect the subject to be right in the mainstream of psychological research. In fact, this has not been the case until very recent times. The reason for this probably lies in the ways in which the field relates to, and feeds from, not only other areas of psychology but other disciplines too. The clearest instance of this relation is in the way the study of reasoning has often seemed to assess people against idealised criteria derived from formal systems such as logic, probability theory, and decision theory. The place of normative standards in the psychological account of thinking and reasoning is one of the core issues we shall be concerned with in this book. Of course, it would be a strange kind of psychology that did not concern itself with thought, and there is now a huge and proliferating literature on reasoning and thinking, informed by the theoretical and empirical methods of both cognitive psychology and cognitive science. So huge, in fact, that I shall have to start by drawing some lines, before outlining what will be covered in this text. Some boundaries First let me reassure those readers who dread having to get to grips with technical systems. Although in studying reasoning you cannot totally avoid contact with logic, and in studying decision making you must at some point look at decision theory and probability, systems such as these will be set out only in as much detail as is necessary for the psychology, and with a minimum of maths. Second, as this field has taken its place in the mainstream of cognitive enquiry, so the borderlines between it and other fields have become blurred. As a consequence, we shall