High Pressure and Black Clouds : Keynes and the Frequentist Theory of Probability

The thesis of this paper is that Keynes wrote A Treatise on Probability contrasting his view to the frequentist theory, systematised by John Venn, which denied to probability any sort of utility in decision theory. Keynes's problem was of finding an alternative theory to be utilised as a guide of life. To analyse this point the paper considers Keynes's criticism to the frequentist tradition in the two versions of dissertation, and in published edition of Treatise. The topic is then illustrated with the famous example of choosing to go out with one's umbrella or not if the pressure is high and the clouds are black