Communism and fascism clearly shared a desire to revolutionize state and society, but there were important differences between them. Following Marx, Soviet Communists strove to create an international brotherhood of workers. In the Communist utopia to come, economic exploitation would disappear and society would be based on radical social equality (see Chapter 21). Under Stalin’s rule, the state aggressively intervened in all walks of life to pursue this social leveling, attacking the upper and middle classes and nationalizing private property (see "The Five-Year Plans").

The Fascist vision of a new society was quite different. Leaders who embraced fascism, such as Mussolini and Hitler, claimed that they were striving to build a new community on a national — not an international — level. Extreme nationalists, and often racists, Fascists glorified war and the military. For them, the nation was the highest embodiment of the people, and the powerful leader was the materialization of the people’s collective will.

Like Communists, Fascists promised to improve the lives of ordinary workers. Fascist governments intervened in the economy, but unlike Communist regimes they did not try to level class differences and nationalize private property. Instead, they presented a vision of a social community bound together by nationalism.

Communists and Fascists differed in another crucial respect: the question of race. Where Communists sought to build a new world around the destruction of class differences, Fascists typically sought to build a new national community grounded in racial homogeneity. Fascists embraced the doctrine of eugenics, a pseudoscience that maintained that the selective breeding of human beings could improve the general characteristics of a national population.

The clash between Communists and Fascists was in large part responsible for the horrific destruction and loss of life in the middle of the twentieth century. Explaining the nature of totalitarian dictatorships thus remains a crucial project for historians, even as they look more closely at the ideological differences between communism and fascism.

One important set of questions explores the way dictatorial regimes generated popular consensus. Neither Hitler nor Stalin ever achieved the total control each sought. Nor did they rule alone; modern dictators need the help of large state bureaucracies and the cooperation of large numbers of ordinary people. Which was more important for generating popular support: terror and coercion or material rewards? Under what circumstances did people resist or perpetrate totalitarian tyranny? These questions lead us toward what Holocaust survivor Primo Levi called the “gray zone” of moral compromise, which defined everyday life in totalitarian societies. (See “Individuals in Society: Primo Levi.”)