Keynes was both a radical and a pragmatist. He was never so attached to a single theory that he was not prepared to abandon it if it seemed not to work. His critics accused him of intellectual incoherence and dilettantism; in fact, Keynes merely built into his thinking what we all know to be true: that uncertainty in life trumps all our abilities to predict the future. Unless you factor in uncertainty, your models will at some point inevitably collapse. Just such a collapse happened in 2008, when the markets did not smoothly “correct” so much as threaten to ruin the global financial system.

Keynesianism isn’t mathematics. It is mathematics mixed with ethics and politics, because that is how Keynes saw the world and, in a remarkable public life, it is how he embraced the world in his time and made his contribution. He was a statesman who was never elected, a financier who made and lost three fortunes, a politician who rebuilt the post World War 2 global economy, and a principled objector to the terms of the Versailles Peace Settlement which were so severe that, Keynes believed, they made World War II inevitable.

His principles survived his death for thirty years before the Chicago school and Reaganism displaced Keynesianism in the US, parts of Europe, though never in the world beyond. Yet the Neo-classical mathematical certainties imploded in 2008. In the debris of the crash, the lost savings, the bankrupted companies and families, the return of governments to bail out industries and banks, the only consistent and coherent guide is provide by John Maynard Keynes. This book describes the survival and return of Keynes’s ideas, and shows how, fifty years after his death, he remains the master.