“Does Badiou maintain unchanged the repeated assertion in BEING AND EVENT (1988) that mathematics is ontology (M=O)? The answer is of course NO! as an examination of a very interesting overview by Badiou of the role of mathematics in his thought: https://medias.ircam.fr/xa3a059
12 mins and after:
a sort of misunderstanding has arisen. In reality I am a looter of mathematics, that is for a certain number of choices that are in fact philosophical about a certain number of questions going far back into the past I realise, or I think I can affirm that mathematics comes to my aid. That is why I came to say…that mathematics is ontology. In reality mathematics is not ontology, because if it were ontology it would say it was ontology, it would say, it’s the case, we deal with Being, etc. So that is a philosophical proposition, it is a proposition proper to me. It signifies in fact something a little different, it is a slogan struck so that it will stick in our minds, to shift the question of ontology. To be frank, it is above all a slogan designed to say something unbearable for Heidegger. That’s it. That’s what it is. It is meant to radically shift the question of Being away from its existential, phenomenological, etc. formulation, which is the formulation that I received and adopted as a child. So it is a struggle against myself, to tell myself: ‘mathematics is ontology, remember it’s not the thing-in-itself, it’s not the opposition of the for-itself and the in-itself, it’s not what gives you nausea’. No, it’s the total opposite of all that. the total opposite, it’s plainly and simply the pure multiple. That’s it. After making this choice, I accompany it, I inject it, I escort it, in effect, into set theory, which is a part of my fairly developed mathematical culture at that time, May 1960 to May 1970, as has previously been mentioned, something I shared with Lacan and a lot of other people otherwise philosophically quite distant from me. I make use of mathematics to give a force of conviction, rational force, to the ontological hypothesis that I propose, that is: anything, whatever constitutes its being, is always a pure form of multiplicity. That’s the primordial proposition. And the mathematics of set theory serves to give clarity and coherence to the question: what is pure multiplicity?”