The concept of weight of argument has been neglected for a long time even by interpreters sympathetic to the basic message of GT who believed that this concept was unimportant, outdated or even wrong. In this chapter we have suggested an interpretation of the concept of weight of argument that we believe to be consistent with the spirit of Keynes's approach and that permits us to confirm the substantial correctness and analytical potential of that approach in the light of the recent advances of DTU. This interpretation has confirmed the practical relevance of the concept, overcoming the doubts expressed by Keynes himself, as well as its crucial role as a foundation for the crucial theoretical and policy message of Keynes. It is thus possible and opportune to resume the research programme that Keynes suggested, with some timidity, to analyse the role of the weight of argument in economic decisions.
- 1. By introducing the usual criterion of normalization of probability measures K + I = 1 (a criterion that Keynes himself had utilized in TP, for example on page 348), this measure also subsumes the first definition.
- 2. A list of interpreters emphasizing discontinuity in Keynes's views on probability may be found in O'Donnell (1990, p. 56), while a list of interpreters claiming continuity may be found in Bateman (1990, p. 73).
- 3. This does not mean that these choices are necessarily irrational in the light of more comprehensive concepts of rationality (see Vercelli, 2005).