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Thinkers

Alain Badiou

Modern European · Europe · born 1937

French thinker who holds that mathematics tells us what being is, and that rare events open new truths.

What it is

Alain Badiou (born 1937) is a French philosopher, born in Rabat, Morocco. He studied at the École Normale Supérieure in Paris, taught at the University of Paris VIII, and later held the chair of philosophy at the École Normale Supérieure.

His work draws on mathematics, above all set theory. He argues that philosophy should take truth seriously, and that new truths enter the world through events that break with the way things stood.

The main ideas

  • Mathematics tells what being is. In his view, the part of philosophy that asks what exists, called ontology, is best done with the tools of set theory.
  • Events. Now and then an event breaks with the way things stood, and truth becomes visible for a moment. Staying faithful to it is what carries it on.
  • Truth and fidelity. A person becomes a subject by meeting an event and staying faithful to what it shows. Truth, on this view, is not just a matter of opinion or of how language is used.
  • Against relativism. He rejects the doubt about truth that he saw as typical of postwar French thought, and defends universal truths.

What it looks like in practice

Imagine someone who, after a chance meeting or a sudden discovery, rearranges a whole life around what it showed, and keeps to it when it would be easier to forget. Badiou would call that kind of staying true a fidelity. For him, truth asks something of a person, not only of a theory. This is an illustration of the idea, not a passage from his writing.

Books and moments

  • Being and Event (1988, in French L'Être et l'Événement) is his central work, using set theory to rethink being.
  • Ethics (1993) is an essay on the understanding of evil.
  • Saint Paul: The Foundation of Universalism (1997) is a book on Saint Paul and the foundation of universalism.
  • Deleuze (1997) is a book on another French philosopher, and Logics of Worlds (2006) follows Being and Event.

Questions and criticism

  • Can mathematics settle what is? It is open whether set theory can do the work of an ontology.
  • Which events count? It is fair to ask how one tells a true event from something that merely feels like one.
  • Truth against language. Thinkers who stress the role of language in shaping what we call true will question his break with that view.

Close neighbours

The pages on Plato and Jacques Lacan are the closest, since he is described as influenced by both, and Gilles Deleuze is the subject of one of his books.

Written by epchē in our own words, and checked against independent sources on 29 October 2026. The sources are listed below.

Who they connect to

Influenced by

  • Jacques Lacan · He took up and argued with Lacan's view of the subject.
  • Jean-Paul Sartre · He grew up under Sartre's influence and kept his stress on commitment. (scholars disagree about this link)
  • Plato · He has written a version of Plato's Republic and calls himself a Platonist of the multiple.

Other Modern European thinkers

Sources we used

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