The Temptation of ‘Radical Plurallism’ in the Old Academy: Plato and Speusippus
(2022) IV International Conference in Greek Philosophy (Sociedad Ibérica de Filosofia Griega) — Location: Universidad Complutense de Madrid, Madrid (25.April.2022)
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- I shall begin with a very short antipodean digression. The very iconoclast view that there is not only one actual world but many was proposed by the Australasian philosopher Richard Routley at the end of the last century. Broadly, he challenged the uniqueness of the actual world by means of the following assumption: the strong connection between epistemology and metaphysics means that any correct theory is a world-description and, consequently, corresponds to an actual world. Of course, details matter (what are the sufficient and necessary conditions of correctness? Is it the facts that ground the theory or the facts are constructed from the theory? etc.), but a crude presentation is enough for my purpose. According to this principle, if there are many correct theories for describing the reality, then there also are many actual worlds. If epistemological relativism is half-true, as is epistemological realism, the antecedent, and so the consequent, are true: there is a plurality of actual worlds. Routley called this view ‘radical pluralism’ or ‘plurallism’. This is a very weird thesis that could be born only in the land of platypus. Nevertheless, the fact is: such a position is discussed by ancient philosophers and, worse, endorsed by some. My paper aims at providing an account of the ancient versions of plurallism, and of its philosophical significance. In Ti. 55c7-d6, Plato asks: ‘how many worlds they are?’ and suggests three answers. The first two are ‘an infinity’ and ‘one’. They are classic and expected responses: either there is one world or many, and if they are many, an infinite set of worlds is more plausible than a finite one measured by an arbitrary number. But Plato offers another answer: ‘five’ (55d2-4). He adds straight away that the real issue is between the supporters of the uniqueness of the world and those of the quintuple worlds (55d2-3). Why? Because, obviously, there cannot be an infinity of worlds (only silly Democritus’ followers can support such a view by lack of rationality, cf. 55c8-d2). By contrast, the eventuality that they are five worlds is taken seriously, and deserves a deeper analyse (55d3-4). Plato puts this study to a later time (55d5-6), and supposes the unicity of the world in accordance with the rest of his discourse (55d4-5). He will never come back to the issue. The traditional reading is due to Plutarch who thinks that, by speaking of a quintuple universe, Plato alludes to the preceding part of Ti. in which Plato assigns a physical item to each of the five regular solids (54d3-55c6). This exegesis is very implausible. Indeed, while four regular solids correspond to the geometrical structure of the four physical elements (55d5-55c4), Plato ascribes the dodecahedron to the world itself (55c4-6). But if the world is dodecahedric and if worldly items are compounds of other regular solids, then these regular solids describe the geometrical pattern of the world. They do not constitute themselves a plurality of separate worlds, but contribute together to the existence of the same world. Another reading has been suggested. Rashed has claimed that these five worlds refer to the objects examined by the five Platonic sciences (R VI 506c-VII 541b, Lg. X 893c-894a, etc.), namely the forms of dialectics, the mathematical ratios of arithmetics, the surfaces of geometry, the solids of stereometry, and, last and least, the moved physical solids of astronomy. In brief, the five-world hypothesis alludes to Plato’s multi-layered vertical hierarchy, and, thus, the question whether there are one or five worlds is reducible to the issue whether there is or not participation between these levels of reality. If so, the worlds in question are actual worlds rather than cosmic worlds. The issue is not cosmological, but belongs to modal metaphysics. Plato does not challenge the Atomist infinity of worlds, but some other Academic or Pythagorean weirdos. Subsequently, the postponed study of 55d5-6 becomes either the whole Ti. or Sph. in which Plato confronts the ‘friends of forms’ who deny participation between sensible and intelligible realms (and, in doing so, they admit the existence of two actual and distinct worlds). From an epistemological point of view, however, the discussion of Ti. 55c7-d6 can be explored as an issue between monist realism and radical plurallism. Plato asks whether a world corresponds to each of the five correct theories, or whether the five correct theories describe the same world. He believes that this last horn is true, but others favour the first. They are two identifiable proponents of radical plurallism in Academy’ neighbourhood: first, the ‘friends of forms’ (often identified to the Socratic Circle of Euclides); second (following Tarrant’s suggestion), Speusippus that Aristotle frequently charges of metaphysical ‘episodism’ because of his cutting of the reality into many principlely autonomous layers (Met. Z.2 1028b21-24, Λ.10 1075b37-1076a4, N.3 1090b13-30). I shall expound the two versions, and emphasize their respective polemic anti-Platonic strength. In doing so, I will show why the question of plurallism matters, at least for Plato.
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Marion, F. (2022). The Temptation of ‘Radical Plurallism’ in the Old Academy: Plato and Speusippus. IV International Conference in Greek Philosophy (Sociedad Ibérica de Filosofia Griega), Universidad Complutense de Madrid, Madrid.