Filozofski vestnik | Volume XLI | Number 2 | 2020 | 341–360 | doi: 10.3986/fv.41.2.13 Jana Ndiaye Berankova* The Immanence of Truths and the Absolutely Infinite in Spinoza, Cantor, and Badiou The relationship between mathematics and ontology and the slogan “mathe- matics is ontology” has been a constant topic of investigation among think- ers who follow Alain Badiou’s philosophical project. In 2018, at the conference Thinking the Infinite at the National Gallery in Prague, Badiou was supposed to give a talk proving the logical necessity of mathematical ontology. Howev- er, instead of providing the final proof that some members of the public were asking for, he delivered a different talk reworked at the last minute. He elicited great perplexity in the room by retracting the slogan “mathematics is ontology” for being nothing but an advertising simplification of a necessarily complex problem.1 He observed that this clear and easily memorable slogan falls into the sphere of the doxa and cannot exhaust the nuanced relationship between the two fields. My intention in the present article will be to provide an interpre- tation of these puzzling remarks along with an exegesis of the mathematical concepts that appear in the recently published third volume of Being and Event: The Immanence of Truths. In this third volume, Badiou relies on the mathemat- ical theory of large cardinals, which addresses sets and classes so large that they can almost approximate the entire universe of numericity. He proposes a renewed theory of the absolute “substance” and of the attributes of the abso- lute. As abstract and complex as such thinking might seem, it builds upon prob- lems which appeared – although in their naïve and schematic form – already in the mathematico-philosophical considerations of Georg Cantor. By reading 341 Badiou’s and Cantor’s texts closely together, we might be able to comprehend the articulation of philosophy and mathematics and the role played by philo- sophical choices. 1 Alain Badiou, “Ontologie et mathématiques : Théorie des Ensembles, théorie des Catégo- ries, et théorie des Infinis, dans L’Être et l’événement, Logiques des mondes et L’imma- nence des vérités”. * Columbia University jana ndiaye berankova Mathematical ontology and its consequences Did Badiou truly disavow the relationship between ontology and mathematics, or more broadly, between philosophy and mathematics? My conviction is that the response to this question might not be scandalous at all: “the discourse of Prague” constitutes nothing but a clarification of the hierarchy between these two fields. Badiou posits that “the thinking of being is a thinking on different forms of the multiple.”2 He departs from the philosophical statement “being is the multiplicity-without-the-one.”3 This starting point is not a mathematical statement. It would thus be misleading to say that “ontology is mathematics” for the latter expression would imply that we can derive knowledge of being di- rectly from mathematics without passing through philosophical decisions and that mathematical inventions must have a direct and immediate effect on our understanding of Being. “Being is the multiplicity-without-the-one”4 is nothing but an initial philosophical decision; it is the philosopher’s choice: the phi- losopher chooses this position over another one by comparing their possible consequences. In other words, the decision situated at the beginning of any philosophical system is an initial “wager”, a “working hypothesis”, perhaps something like a philosophical “axiom”. Such an “axiom” can be legitimated only by the richness of its consequences. The dialogue between mathematics and philosophy can be portrayed as follows: “a philosopher outlines a certain idea, and then uses mathematics, wherein this idea can be verified, and in the end returns to philosophy.”5 It is the “very construction of the [philosophical] system [that] proves the statement. This means that this initial statement is a posteriori proven and vindicated thanks to the scope of its consequences. But we never have demonstrative certainty which would resemble mathematical formalism.”6 In the present volume, Badiou states similarly that “the alliance 342 organized between mathematics and philosophy becomes strong only when we observe its consequences.”7 In other words, mathematics is but philosophy’s methodological tool for verifying its initial philosophical hypotheses. The phi- 2 Interview with Alain Badiou on The Immanence of Truths, Paris, 13 February 2018. 3 See p. 22 in the present volume. 4 See p. 30 in the present volume. 5 Jana Beránková, “Communism is a New Idea, Interview with Alain Badiou by Jana Beránk- ová”, Contradictions 2 (2/2018), p. 118. 6 Ibid., 118. 7 See p. 22 in the present volume. the immanence of truths and the absolutely infinite in spinoza, cantor, and badiou losopher needs mathematics in order to build a method, and it is in this sense that a great part of ontology remains “mathematical”, and yet we cannot affirm that philosophical statements are deduced directly from mathematics. To the philosopher, mathematics is but a modality to develop his or her thought; the origin and the finality of thinking remains philosophical. In fact, ontology is grounded in philosophy, not in science. In Prague, Badiou merely clarified the hierarchy between these two fields by alluding to the ineluctable arbitrariness of philosophical decisions; in no manner did he reject the relationship between ontology and mathematics. Instead of “mathematics is ontology,” it might be more exact to say that “ontology uses mathematics as a methodological instru- ment for creating a possibility of our understanding of being.” Mathematics is a mere condition of philosophy along with politics, art, and love. The relationship between philosophy and mathematics is not that of “suture”: philosophy is not sutured to anything; it highlights the existence of truth procedures in its condi- tions (science qua mathematics being one of them). Note that in the above cited passages, the relationship between mathematics and philosophy is portrayed on the basis of inductive, not deductive, reason- ing. Here, the induction generates the possibility of building up a philosoph- ical system from mathematical grounds. As long as mathematics assists phi- losophers by successfully elucidating otherwise unsolvable problems, its use in ontology is legitimate. Such reasoning sounds surprisingly Gödelian, for it can call to mind the concluding paragraph of Kurt Gödel’s 1947 article “What is Cantor’s Continuum Problem?”: “There might exist axioms so abundant in their verifiable consequences, shedding so much light upon a whole field, and yielding such powerful methods for solving problems (and even solving them constructively, as far as that is possible) that, no matter whether or not they are intrinsically necessary, they would have to be accepted at least in the same 343 sense as any well-established physical theory.”8 Badiou – who valued Gödel’s article for the emphasis it placed on the role that mathematical intuition and axiomatic decisions play in solving mathematical problems9 – remarked that “Every thought – and therefore, mathematics – sets off decisions (intuitions) 8 Kurt Gödel, “What is Cantor’s Continuum Problem?”, in Collected Works, Vol. II, Publica- tions 1938–1974, Oxford University Press, Oxford 1990, p. 261. 9 See Badiou’s comments on Gödel’s article in Briefings on Existence: A Short Treatise on Transitory Ontology, State University of New York Press, Albany 2006, p. 92. jana ndiaye berankova from the standpoint of the undecidable (of nondeductible inference).”10 Ontolo- gy’s use of mathematics is nothing but an initial decision that can be justified a posteriori by the solutions it provides to otherwise unsolvable problems. Critics of Badiou’s mathematical ontology (some of whom are included in this volume) tend to see as deduction what in reality is inductive reasoning. The criticism usually follows this trajectory: If set theory is ontology (i.e. a rational discourse on being qua being defined as an inconsistent multiplicity without the one), could some other mathematical theory (e.g. category theory, mereol- ogy)11 be ontology too? Why should we privilege set theory, an obscure field of knowledge that seems to be but a burden to many working mathematicians? These questions are legitimate but also tautological. For had we departed from a different philosophical axiom, e.g. that “being is a pure multiplicity without the one,” a different mathematical or scientific theory might be much more suitable to our thinking. It is very likely possible to build ontology on a different basis than a set-theoretical basis. Any true criticism cannot dispense with the long and laborious task of system building. The usefulness of a given mathemati- cal theory for philosophical thought can only be seen after we have sketched and exhausted its consequences in the domain of philosophy. Thinking moves from ontology to mathematics and not vice versa. A correct reasoning cannot be “there is theory y in mathematics, therefore being must be x,” but rather: “being is x, therefore we should use mathematical theory y to develop our reflection.” And even this second reasoning can be vindicated only a posteriori depending on the fruitfulness of its consequences. Philosophy cannot have the certitude of a mathematical formalism; it is consistent but necessarily incomplete. It begins with an axiom and not with a totalising origin that would close its field of the possible. Philosophical axioms, the statements in which the long trajectory of 344 thought originates, can be verified only a posteriori, after accomplishing a cer- tain philosophical journey. Only by elaborating a different and similarly com- plex philosophical system grounded in a competing statement that “ontology is y” will it be possible to measure the richness of its consequences with those of Badiou’s set-theoretical ontology. Philosophical “working hypotheses” do not 10 Alain Badiou, Briefings on Existence: A Short Treatise on Transitory Ontology, State Univer- sity of New York Press, Albany 2006, p.