The Concept of the Weight of Argument

Abstract

The novel concept of ‘the weight of argument’ forms a significant element in Keynes’s philosophy and has a particular bearing upon his economics. Although it was somewhat hesitantly advanced in the TP, he lent further importance to it in his economic writings after 1930, even if it remained in the background or was concealed by proxies such as ‘confidence’. Its general significance lies in its relevance to his theory of rationality under uncertainty, its particular significance in the light it casts on uncertainty and liquidity in the GT.

It seems plain that there is some sense in which a probability founded upon more evidence is superior to one founded upon less.

J.M. Keynes 1907

… the ‘weight’ and the ‘probability’ of an argument are independent properties.

J.M. Keynes 1921

By ‘very uncertain’ I do not mean the same thing as ‘very improbable’ Cf. my Treatise on Probability, chap. 6, on ‘The Weight of Arguments’.

J.M. Keynes 1936

I am rather inclined to associate … liquidity premium with what in my Treatise on Probability I called ‘weight’.

J.M. Keynes 1938¹