The Rebel is an essay on artistic, historical, and metaphysical rebellion, in which he lays out the difference between revolution and revolt.

Camus sees revolt as a peaceful, evolutionary process that requires leadership but not violence. He criticizes Hegel's work, accusing it of glorifying power and the state over social morality and ethics, and he accuses Marx of co-opting Hegelian philosophy to allow "any means to an end". Camus prefers Mediterranean humanism, a philosophy grounded in nature and moderation, to the violence and historicism he sees as part and parcel to what he calls the "Absolutist" philosophies. The attacks on Hegel, Marxism and nihilism in The Rebel had a profound effect on Camus' peers.

The book was described as intellectual treason by leftist critics, and a review by Francis Jeanson in Les Temps Modernes accused Camus of being a traitor to the left. After Camus attempted to defend himself in a letter to the publication, Jean-Paul Sartre, the editor of Les Temps Modernes at the time, published an open letter in response that tallied 19 pages. The letter included personal attacks, and marked the end of the two philosophers' friendship.