A Treatise on Probability and “My Early Beliefs”
T. Hirai
Abstract
The purpose of this paper is to examine Keynes as a philosopher in view of
the relation among A Treatise on Probability (1921), Ramsey’s criticism (1926), Keynes’s considerable degree of acceptance of Ramsey’s criticism (1931), My Early Beliefs (1938), and Keynes’s criticism of Tinbergen (1939).
The conclusion runs as follows;
(1)In his youth, Keynes firmly believed in human rationality, the philosophical work of which is his Treatise on Probability. But he became more and more skeptical of human rationality and conscious of the emotional aspect of human nature, in the midst of the chaos of the post-WWI Europe, which is typically shown in his criticism of the market society and his advocacy of the New Liberalism in The End of Laissez-Faire (1926). As years went by, Keynes’s skepticism or human rationality became deeper and deeper and came to stress the importance of custom and tradition, which he came to revaluate the market society in face of the cruel realities of the Soviet society.
(2)Keynes abandoned the most essential part of his Treatise on Probability, which lies in regarding probability as degrees of rational belief between propositions, and the justification of induction based on it, in front of Ramsey’s criticism. This is evidently recognizable in his obituary of Ramsey and My Early Beliefs. However, he did not abandon his theory of probability completely, which is shown in his critical review of Tinbergen (1939). In Part V (The Foundations of Statistical Inference) of A Treatise on Probability Keynes had criticized the mathematical use of statistical frequencies (Methods of Laplace) and defended the inductive use of them (Methods of Lexis). Keynes’s criticism of Tinbergen’s method is mainly based on this stance. We have Keynes who accepted Ramsey’s criticism on the one hand, and retained the Methods of Lexis on the other. There seems to run a logical fissure between Part III (Induction and Analogy) and Part V.
1. Introduction
2. The Stance of A Treatise on Probability
2.1 Definition of Probability
2.2 Question of Whether Probability Is Objective or Subjective
2.3 Sphere of Object
2.4 Argument for Justification of Induction
3. After the Treatise ― Influences from Ramsey’s Criticism
3.1 Ramsey’s Criticism
3.2 Keynes’s Response
4. On “My Early Beliefs”
5. Keynes as “a Philosopher” and as “an Economist”
5.1 The General Theory
5.2 Keynes’s View of the Nature of Economics
5.3 Two Problems
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