In his article, ‘Un, multiple, multiplicité(s)’ (2000), Badiou reiterates his earlier objections to Deleuze: (1) Deleuze's conception of ‘set’ is anachronistic because it is pre-Cantorian. It ignores the extraordinary immanent dialectic that mathematics has bestowed (dotē) this concept since the end of the nineteenth century; (2) Deleuze's concept of multiplicity remains inferior (because of its qualitative differentiation) to the concept of multiple emerging from the history of contemporary mathematics; and (3) the qualitative determination of multiplicities makes it impossible to subtract them from their equivocal re-absorption into the One (of classical ontology). In the same article, Badiou complains that those who attacked his interpretation of Deleuze (that is, Arnaud Villani and José Gil) (1998) missed their mark because they failed to take into account the ontological alternative he provides in L‘être et l'évènement (hereafter EE):

It is not my intention to revisit the question of whether Deleuze is, or is not, committed to a unitary conception of Being. Instead, I want to focus my attention on Badiou's own ontology. In particular, I want to examine the implications that Badiou's mathematical ontology has for his theory of the event.