Peter Singer identifies the central vision that unifies Marx's thought, enabling us to grasp Marx's views as a whole. He sees him as a philosopher primarily concerned with human freedom, rather than as an economist or a social scientist. He explains alienation, historical materialism, the economic theory of Capital, and Marx's ideas of communism, in plain English, and concludes with an assessment of Marx's legacy.

Many people regard Hegel's work as obscure and extremely difficult, yet his importance and influence are universally acknowledged. Professor Singer eliminates any excuse for remaining ignorant of the outlines of Hegel's philosophy by providing a broad discussion of his ideas and an account of his major works.