Abstract: This is an overview of the writings of John Maynard Keynes. It shows that a logically coherent structure of ideas, based on a single vision, permeated all aspects of Keynes's thought. This vision integrated Keynes's theories of probability and uncertainty with his moral and political philosophy.Keynes's probability theory rejected both pseudo-quantification and undue scepticism. His macroeconomics assumed that the world was complex and changing, and that many elements in a decision could not be meaningfully quantified. In many respects, his political philosophy, which was meant to be a third way to Marxism and laissez-faire, reflected his economics. It treated the economy neither as a perfect machine nor as a system doomed to failure, but as a fallible human institution subject to judgement, and improvable by human reason.All of Keynes's writings are considered, including his unpublished early works. This history of economic thought discusses the meaning and development of Keynes's system, considers how it changed over time, and shows that he was misled by an exaggerated notion of the power of ideas.

Keywords: economics, John Maynard Keynes, philosophy, practical reason, probability, third way, uncertainty