A cruel, silly but not entirely inaccurate way of defining A Theory of Justice, the central work in the philosophy of John Rawls (1921-2002), is to call it the greatest book nobody has ever read. Since it was first published in 1971 the book has had an enormous influence throughout the West and in most of the East that aspires to democracy, but it is hard even to quote from, let alone summarise. Most students of modern history know that Rawls invented the Difference Principle but few of them would find it easy to explain. With his emphasis on fair distribution through state initiatives, Rawls’s initial appeal is mainly to the left, but left-wing thinkers usually do a bad job of summing him up because they find his acceptance of capitalism reactionary and his tolerance of social discrepancies unpalatable.