ABSTRACT
As pointed out by the editors of this volume, in a letter to me elaborating on their kind invitation to contribute to this volume, 'the theory of risk was one of Sir John's main preoccupations'. One of his first theoretical studies was his 1931 Economica article 'Uncertainty and profit', and the last chapter of his last book, completed just before he passed away, was 'Risk and uncertainty', an appendix to his 1989 A Market Theory of Money. In between, he returned to the subject on many occasions, especially in 'The theory of portfolio selection' (in his 1967 Critical Essays in Monetary Theory) and 'The disaster point in risk theory' (in his 1977 Economic Perspectives).
