Abstract
If the object of Althusser’s main theoretical work was Marx’s historical materialism, the form this work took was philosophy. Philosophy was his most important object. His reflections focused on the question of the existence of a Marxist philosophy, on philosophy as practice, the practice of philosophy and its role in ideological and political class struggles. This article sets out to understand how what is somewhat improperly called Althusser’s ‘last’ philosophy, the materialism of the encounter or aleatory materialism, is the philosophy that renounces the dominant form of philosophy to take the form of what I would call a counter-philosophy.