First published 1963 by Routledge & Kegan Paul

First published in Routledge Classics 2002
by Routledge
2 Park Square, Milton Park, Abingdon, OX14 4RN
711 Third Ave, New York, NY10017

Routledge is an imprint of the Taylor & Francis Group

© 1963, 1965, 1969, 1972, 1989 Karl Popper

© 1994, 2002 The Estate of Karl Popper

Typeset in Joanna by RefineCatch Limited, Bungay, Suffolk

All rights reserved. No part of this book may be reprinted or reproduced or utilised in any form or by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying and recording, or in any information storage or retrieval system, without permission in writing from the publishers.

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
A catalog record for this book has been requested

ISBN 10: 0-415-28593-3 (hbk)
ISBN 10: 0-415-28594-1 (pbk)

ISBN 13: 978-0-415-28593-3 (hbk)
ISBN 13: 978-0-415-28594-0 (pbk)