1. Introduction

The introduction anticipates the main arguments advanced in the book, which are: (a) The relevance of A Treatise on probability to understand Keynes’s methodological way of reasoning and his idea of rationality as reasonableness; A Treatise on Probability is relevant to Keynes’s economics. There is a continuity in Keynes’s way of reasoning, from A Treatise on Probability to Indian Currency and Finance, the General Theory and on to Keynes’s Plan for Bretton Woods; (b) Keynes advances a philosophy of measure in his approach to probability and transfers this philosophy from probability to economics; (c) Keynes investigates some complex or manifold magnitudes and the impossibility to measure them by a single unit of measure. These complex magnitudes are probability, goodness, beauty, utility, the general price level, aggregate capital and output as a whole. So, the theme of incommensurability (intrinsic non-measurability) of magnitudes is central in his thought (Chapter 3); (d) To understand Keynes’s way of reasoning, it is fundamental to analyse his way of criticising the classical economic theory and to compare it with his own way of reasoning both in A Treatise on Money and in the General Theory. He always searches for logical fallacies in economic reasoning; he is like a detective in search for tacit premises, tracking down logical fallacies in economic reasoning (Chapter 4); (e) Greek tragedy and irreducible conflicts and dilemmas are central in Keynes’s thought and are at the root of his idea of uncertainty. Keynes’s way of reasoning and his idea of tragic irreducible conflicts and dilemmas are a constant, not only in his macroeconomics but also in his approach to international relations, from his early book on Indian Currency and Finance (1913) to his Plan for Bretton Woods and the Clearing Union and his 1945 Memorandum (Chapter 5 and Chapter 8); (f) His anti-utilitarian ethics is rooted in the Greek ethics of virtue (a life worth to be lived) and in the Aristotelian happiness as eudaimonia. Tragic beauty and the sublime are also relevant to his view on aesthetics. Happiness is, for Keynes, the ultimate end of life in contrast to the capitalist love of money. The introduction also briefly lists some of the widespread misinterpretations of Keynes’s way of reasoning against which I argue in the book. I argue against the so-called discontinuity thesis, defended by Bateman, O’Donnell and Winslow; against the interpretation of Keynes’s concept of ‘radical uncertainty’ based on non-ergodic statistical processes of the material-empirical universe, advanced by Davidson and his followers; against the interpretation of Keynes as a follower of the critical realism ontology à la Bashar, advanced by Lawson; against the widespread behaviourist view on the stabilising role of conventions in Keynes’s view on expectations; against the interpretation, according to which, Keynes finally embraces Hume’s philosophy after having fully criticised it in his A Treatise on Probability (Andrews, Dow). I also argue that Keynes is not a Keynesian (a bastard Keynesian), a neo-Keynesian nor a post-Keynesian.