Karl Popper - The Logic of Scientific Discovery

Logik der Forschung first published 1935

by Verlag von Julius Springer, Vienna, Austria

First English edition published 1959

by Hutchinson & Co.

First published by Routledge 1992

First published in Routledge Classics 2002 by Routledge

11 New Fetter Lane, London EC4P4EE 29 West 35th Street, New York, NY 10001

Routledge is an imprint of the Taylor el Francis Croup

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1959, 1968, 1972, 1980 Karl Popper 1 999. 2002 The Estate of Karl Popper

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.

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ISBN 0-203-99462-0 Master e-book ISBN

ISBN 0-415-27843-0 (hbk) ISBN 0-415-27844-9 (pbk)

TO MY WIFE who is responsible for the revival of this book

Contents

Translators' Note xii

Preface to the First Edition, 1934 xv

Preface to the FirstEnclish Edition, 1959 xviii

PART I Introduction to the Logic of Science

1 A Survey of Some Fundamental Problems 3

1 The Problem of Induction

2 Elimination of Psychologism

3 Deductive Testing of Theories

4 The Problem of Demarcation

5 Experience as a Method

6 Falsifiability as a Criterion of Demarcation

7 The Problem of the 'Empirical Basis'

8 Scientific Objectivity and Subjective Conviction

2 On the Problem of a Theory of Scientific Method 27

9 Why Methodological Decisions are Indispensable 70 The Naturalistic Approach to the Theory of Method 11 Methodological Rules as Conventions

Viii CONTENTS

PART II Some Structural Components of a Theory of Experience

3 Theories 37

12 Causality, Explanation, and the Deduction of Predictions

13 Strict and Numerical Universality

14 Universal Concepts and Individual Concepts 75 Strictly Universal and Existential Statements 7 6 Theoretical Systems

77 Some Possibilities of Interpreting a System of Axioms

t8 Levels of Universality. The Modus Tollens

4 Falsifiability 57 79 Some Conventionalist Objections

20 Methodological Rules

27 Logical Investigation of Falsifiability

22 Falsifiability and Falsification

23 Occurrences and Events

24 Falsifiability and Consistency

5 The Problem of the Empirical Basis 74

25 Perceptual Experiences as Empirical Basis: Psychologism

26 Concerning the So-Called 'Protocol Sentences'

27 The Objectivity of the Empirical Basis

28 Basic Statements

29 The Relativity of Basic Statements. Resolution of Fries's Trilemma

30 Theory and Experiment

6 Degrees of Testability 95 37 A Programme and an Illustration

32 How are Classes of Potential Falsifiers to be Compared?

33 Degrees of Falsifiability Compared by Means of the Subclass Relation

34 The Structure of the Subclass Relation. Logical Probability

35 Empirical Content, Entailment, and Degrees of Falsifiability

CON

37 Logical Ranges. Notes on the Theory of Measurement

38 Degrees of Testability Compared by Reference to Dimensions

39 The Dimension of a Set of Curves

40 Two Ways of Reducing the Number of Dimensions of a Set of Curves

Simplicity

47 Elimination of the Aesthetic and the Pragmatic Concepts of Simplicity

42 The Methodological Problem of Simplicity

43 Simplicity and Degree of Falsif ability

44 Geometrical Shape and Functional Form

45 The Simplicity of Euclidean Geometry

46 Conventionalism and the Concept of Simplicity

Probability

47 The Problem of Interpreting Probability Statements

48 Subjective and Objective Interpretations

49 The Fundamental Problem of the Theory of Chance

50 The Frequency Theory of von Mises 57 Plan for a New Theory of Probability

52 Relative Frequency within a Finite Class

53 Selection, Independence, Insensitiveness, Irrelevance

54 Finite Sequences. Ordinal Selection and Neighbourhood Selection

55 n-Freedom in Finite Sequences

56 Sequences of Segments. The First Form of the Binomial Formula

57 Infinite Sequences. Hypothetical Estimates of Frequency

58 An Examination of the Axiom of Randomness

59 Chance-Like Sequences. Objective Probability

60 Bernoulli's Problem

61 The Law of Great Numbers (Bernoulli's Theorem)

62 Bernoulli's Theorem and the Interpretation of Probability Statements

CONTENTS

64 Elimination of the Axiom of Convergence. Solution

of the 'Fundamental Problem of the Theory of Chance'

65 The Problem of Decidability

66 The Logical Form of Probability Statements

67 A Probabilistic System of Speculative Metaphysics

68 Probability in Physics

69 Law and Chance

70 The Deducibility of Macro Laws from Micro Laws ji Formally Singular Probability Statements

72 The Theory of Range

9 Some Observations on Quantum Theory 209

73 Heisenberg's Programme and the Uncertainty Relations

74 A Brief Outline of the Statistical Interpretation of Quantum Theory

75 A Statistical Re-Interpretation of the Uncertainty Formulae

76 An Attempt to Eliminate Metaphysical Elements by Inverting Heisenberg's Programme; with Applications

77 Decisive Experiments

j8 Indeterminist Metaphysics

10 Corroboration, or How a Theory Stands up to Tests 248

79 Concerning the So-Called Verification of Hypotheses

80 The Probability of a Hypothesis and the Probability of Events: Criticism of Probability Logic

81 Inductive Logic and Probability Logic

82 The Positive Theory of Corroboration: How a Hypothesis may 'Prove its Mettle'

S3 Corroborability, Testability, and Logical Probability

84 Remarks Concerning the Use of the Concepts 'True' and 'Corroborated'

85 The Path of Science

APPENDICES

i Definition of the Dimension of a Theory 283

ii The General Calculus of Frequency in Finite Classes 286

CONTENTS Xi

INDICES, compiled by Dr. J. Agassi

Name Index Subject Index

489 494

Translators' Note

The Logic of Scientific Discovery is a translation of Logik der Forschung, published in Vienna in the autumn of 1934 (with the imprint '1935'). The translation was prepared by the author, with the assistance of Dr. Julius Freed and Lan Freed.

The original text of 1934 has been left unchanged for the purpose of the translation. As usual, the translation is a little longer than the original. Words and phrases for which no equivalent exists had to be paraphrased. Sentences had to be broken up and rearrangedthe more so as the text to be translated was highly condensed: it had been drastically cut several times to comply with the publisher's requirements. Yet the author decided against augmenting the text, and also against restoring cut passages [except for a few words indicated by square brackets or footnotes].