STOIC ONTOLOGY AND PLATO’S SOPHIST JOHN SELLARS Much has been written, both in antiquity and in recent scholarship, about the relationship between Stoicism and Platonism. 1 In antiquity Antiochus claimed that Stoicism advanced little on the Platonic doctrines of the Old Academy: Zeno’s philosophy is simply a modified version of that of his Platonic teacher Polemo. 2 While some modern commentators have tried to highlight the differences between the two philosophies others have, like Antiochus, emphasized the debt that Stoicism owes to Platonism. These sorts of arguments have been made with regard to ethical doctrines and physical doctrines, but here my concern is with ontology. What is the nature of the relationship between Stoic ontology and Platonism? ‘Platonism’ is of course a notoriously slippery word and can mean many things to many people. Following what I assume to be the most common usage of the word, I shall take Platonism to refer to the ontological position that we find in the ‘middle period’ dialogues such as the Republic. Thus in what follows Platonism refers to an ontological position in which unchanging, universal Ideas or Forms grasped by the intellect have an ontological priority over the material world of flux grasped by the senses. 3 It has been suggested that Stoic ontology should be conceived as a reaction against Platonism thus understood. It has also been suggested that Stoic ontology be conceived as a ‘reversal’ of Platonism, 4 inverting the order of priority between bodies and incorporeals, or particulars and universals, depending how one views it. The most significant attempt to analyse the relationship between Stoic ontology and the work of Plato, however, must be 1 Abbreviations: LS = A. A. Long and D. N. Sedley, The Hellenistic philosophers, 2 vols (Cambridge 1987); SSR = Socratis et socraticorum reliquiae, ed. G. Giannantoni, 4 vols (Naples 1990); SVF = Stoicorum veterum fragmenta, ed H. von Arnim, 4 vols (Leipzig 1903-24). An earlier version of this paper was read at the ICS seminar organized by Anne Sheppard and Bob Sharples. I thank them both for the invitation to speak and the subsequent invitation to contribute to this volume. I should also like to thank the seminar audience for their helpful comments, including Peter Adamson, Verity Harte, Richard Sorabji, and Jula Wildberger, as well as our two hosts. 2 See Cicero, Acad. 1.43. For a helpful discussion of Polemo’s influence on Zeno see J. Dillon, The heirs of Plato (Oxford 2003), 156-77. 3 Whether Plato himself ever held this position is of course another matter. 4 This is a claim made by G. Deleuze, Logique du sens (Paris 1969), where he says that the Stoics were the first to reverse Platonism. However he doesn’t specify how he thinks they achieved this and his account of Stoic ontology is eccentric to say the least (on which see J. Sellars, ‘Aiôn and Chronos: Deleuze and the Stoic theory of time’, Collapse 3 (2007) 177-205 (178 n. 4)). Elsewhere, in Différence et répétition (Paris 1968), he claims that Plato himself was the first to reverse Platonism. 183