How far can a single leader alter the course of history? Thomas Carlyle, who promoted the Great Man Theory, says that talented leaders are the primary – if not the sole – cause of change. This view has been challenged by social scientists who understand that leaders are not only constrained by their societies, but merely products of them. Whatever this interplay between a personality and his society, it raises the question of whether dictators are as unconstrained as they seem, and if so, how do they attain that power?

Today’s guest is Ian Kershaw, author of Personality and Power. We look at an array of case-studies of twentieth-century European leaders – some dictators, some democrats – and explore what was it about these leaders, and the times in which they lived, that allowed them such untrammelled and murderous power, and what factors brought that era in Europe to an end?