Book contents
- Frontmatter
- Contents
- General Introduction
- Editorial Foreword by R. B. Braithwaite
- Editorial Note
- Preface to the First Edition
- I FUNDAMENTAL IDEAS
- II FUNDAMENTAL THEOREMS
- III INDUCTION AND ANALOGY
- 18 INTRODUCTION
- 19 THE NATURE OF ARGUMENT BY ANALOGY
- 20 THE VALUE OF MULTIPLICATION OF INSTANCES, OR PURE INDUCTION
- 21 THE NATURE OF INDUCTIVE ARGUMENT CONTINUED
- 22 THE JUSTIFICATION OF THESE METHODS
- 23 SOME HISTORICAL NOTES ON INDUCTION NOTES ON PART III
- IV SOME PHILOSOPHICAL APPLICATIONS OF PROBABILITY
- V THE FOUNDATIONS OF STATISTICAL INFERENCE
- Bibliography
- Index
19 - THE NATURE OF ARGUMENT BY ANALOGY
from III - INDUCTION AND ANALOGY
Published online by Cambridge University Press: 05 November 2012
- Frontmatter
- Contents
- General Introduction
- Editorial Foreword by R. B. Braithwaite
- Editorial Note
- Preface to the First Edition
- I FUNDAMENTAL IDEAS
- II FUNDAMENTAL THEOREMS
- III INDUCTION AND ANALOGY
- 18 INTRODUCTION
- 19 THE NATURE OF ARGUMENT BY ANALOGY
- 20 THE VALUE OF MULTIPLICATION OF INSTANCES, OR PURE INDUCTION
- 21 THE NATURE OF INDUCTIVE ARGUMENT CONTINUED
- 22 THE JUSTIFICATION OF THESE METHODS
- 23 SOME HISTORICAL NOTES ON INDUCTION NOTES ON PART III
- IV SOME PHILOSOPHICAL APPLICATIONS OF PROBABILITY
- V THE FOUNDATIONS OF STATISTICAL INFERENCE
- Bibliography
- Index
Summary
All kinds of reasoning from causes or effects are founded on two particulars, viz. the constant conjunction of any two objects in all past experience, and the resemblance of a present object to any of them. Without some degree of resemblance, as well as union, ’tis impossible there can be any reasoning.
Hume.1. Hume rightly maintains that some degree of resemblance must always exist between the various instances upon which a generalisation is based. For they must have this, at least, in common, that they are instances of the proposition which generalises them. Some element of analogy must, therefore, lie at the base of every inductive argument. In this chapter I shall try to explain with precision the meaning of analogy, and to analyse the reasons, for which, rightly or wrongly, we usually regard analogies as strong or weak, without considering at present whether it is possible to find a good reason for our instinctive principle that likeness breeds the expectation of likeness.
2. There are a few technical terms to be defined. We mean by a generalisation a statement that all of a certain definable class of propositions are true. It is convenient to specify this class in the following way. Iff(x) is true for all those values of x for which ϕ(x) is true, then we have a generalisation about ϕ and f which we may write g(ϕ,f). If, for example, we are dealing with the generalisation, ‘All swans are white’, this is equivalent to the statement, “x is white” is true for all those values of x for which “x is a swan” is true’.
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- Information
- The Collected Writings of John Maynard Keynes , pp. 247 - 258Publisher: Royal Economic SocietyPrint publication year: 1978