After some decades of transition, in the first half of the first century bc, (almost) everything changed. This happened in the Stoa, where non-Athenian scholarchs felt the need for new perspectives, and for a clearer integration of Plato’s doctrine.1 This happened in the Garden, which found new life in Italy with Philodemus’ ‘adaptation’.2 This happened in the Peripatos, where both the recovery of Aristotle’s esoteric writings (in whatever form this may have occurred) and the introduction of a new approach to Aristotle’s philosophy ushered in a new era.3 More generally, the so-called decentralisation of philosophy strongly affected all schools, and determined the need for new ways of thinking and new approaches to authoritative texts.

From Plato’s generation onwards it became the practice among leading philosophers to set up a school within one’s own lifetime, and upon one’s own death either to bequeath its headship to one’s own chosen successor, or to entrust to the school’s members the task of electing the next head. It was only with that succession, when the school’s intellectual legacy needed to be defined and secured, that the founder’s authoritative status was likely to come to the fore. The process is nowhere better illustrated than in the Early Academy.

In a recent article, George Boys-Stones (2018b) offered an interesting definition of the Imperial Platonist conception of authority. According to him, contrary to the members of the other Hellenistic schools, the Middle Platonists do not aim to acquire a sum of propositional knowledge to be preserved within the school. Plato’s authority was for them not that of a founder of a school, but that of a man who had seen the intelligible Forms and discovered a truth to which all subsequent Platonists aspired. According to Boys-Stones, this conception of authority goes hand in hand with a certain epistemological perspective, the traces of which we can find in the fragments of Numenius, most notably in how he thinks of the relation between the second and the third God (fr. 11 des Places). The perspective of this paper is slightly different.

It is a well-known feature of the later Neoplatonist writings from the fifth century ad onwards that the authors frequently refer to their own philosophical teachers. The standard formula, which is almost invariably used on these occasions, is ho hēmeteros kathēgemōn (ὁ ἡμέτερος καθηγεμών, ‘our teacher’); it is attested about thirty times in Proclus, ten times in Simplicius and, with a lower frequency, in Damascius and others. The custom is not wholly unprecedented. Philosophers and medical writers from earlier in the Imperial age, such as Plutarch and Galen, sometimes use similar commemorative formulas, and there may even have been precedents in Hellenistic Epicureanism.

If one had to provide a formal account of what ‘being a Platonist’ means, it would be tempting to refer to the broad idea that a Platonist is, in general, a follower of Plato, which implies a commitment to Plato’s authority. After all, this would be a reasonable description for all heirs of Plato, from the Academics – the scholarchs of the Academy were in any case the successors of Plato, and claimed for themselves the privilege of this relationship – to late-antique Platonists, who regarded themselves as exegetes and interpreters of Plato’s thought. Things are not that easy, however, for once one examines such a general account in detail a series of serious questions emerge. A first – and clearer – puzzle is related to the discontinuity of the tradition: while on the one hand one can say that there is a continuous stream of heirs of Plato from the Early Academy to late Neoplatonism, on the other it is quite obvious that, even admitting a strong continuity between Middle Platonism and Neoplatonism, the philosophical history of the ‘Platonist tradition’ from the Early Academy to the early Imperial Age hardly constitutes a unified whole. As a consequence, just stating that all followers of Plato were committed to his authority would amount to an empty and uninformative statement: the more one generalises the notion in order to make it comprehensive, the less it is specific and able to really include the distinguishing features of each stage of the tradition.

The distinction between Middle Platonism and Neoplatonism is controversial, but it remains helpful in that it makes it clear that there are important differences in the philosophical background of Platonist philosophers before and after Plotinus.1 One of these differences resides in their knowledge of Aristotle’s treatises. It can plausibly be argued that Platonist philosophers, from at least Eudorus of Alexandria onward (first century bc), regarded Aristotle as an authority, though not unqualifiedly so, and though his status was clearly inferior to that of Plato.2 Eudorus of Alexandria was certainly involved in the early debates on Aristotle’s Categories, and we know from Alexander of Aphrodisias (in Metaph. 58.25–59.8) that Eudorus proposed an emendation to Aristotle’s report on Plato’s theory of principles at Metaph.

In the preceding chapter I traced the basis on which Xenocrates, Plato’s second successor as head of the Academy, created the original textual canon for building a Platonic system. It emerged that his authoritative Platonic texts were two myths – the creation myth of the Timaeus, and the Phaedrus’ mythical travelogue about the destiny of eternal souls. The latter passage, I argued, was so canonical as to determine, on occasion, how even the former should be interpreted.

As we shall see in the course of this chapter, a similar approach to Plato’s use of characters in his dialogues can be found in Proclus, Olympiodorus and elsewhere.4 Twenty-first century readers of Plato, conscious of the need to appreciate Plato’s dialogues as works of literature as well as philosophy, may well be struck by remarks like these,5 and may wonder how the Neoplatonists of late antiquity reconciled their awareness of Plato’s skill in characterization with treating Plato as a philosophical authority. That will be my topic in this chapter. I begin with a brief discussion of some modern interpreters who emphasize Plato’s use of dialogue form, from which we shall see that even in our postmodern age such an emphasis can still be combined with a belief that Plato is a dogmatic philosopher. I will then turn to fuller examination of the interpretation of Plato’s characters by Proclus and Olympiodorus, including how this relates to their acceptance of Plato’s authority.

Aristotle plays a highly authoritative role in Neoplatonic philosophy, second only to the almost undisputed authority of Plato. However, as any reader of Plato’s and Aristotle’s works knows, the views of the two philosophers often diverge and generate conflicts. These conflicts provide the Neoplatonic commentators with a serious interpretative challenge: although, as Platonists, their main goal is to defend Plato and the Platonist position, they are also hesitant to openly criticise Aristotle, who is regarded as a true adherent of Plato’s philosophy. The commentators most prominently face such a challenge in the case of the self-moving soul, a core Platonic doctrine severely criticised by Aristotle, implicitly in Physics 8.5 and explicitly in De anima 1.3.

Within the Pythagorean tradition the supreme source of authority is, needless to say, Pythagoras himself. The Pythagoreans are the only Pre-socratics named after the founder of their brotherhood. However, if one takes into account the amount of extant Pythagorean literature, which is for the most part apocryphal – as is well known, the amount of apocryphal Pythagorean literature by far exceeds the few fragments which can be considered authentic and safely attributed to ancient Pythagoreans – the predominant name is that of Archytas, who was undoubtedly a prominent figure, although not one as authoritative as Pythagoras. Moreover, a great number of pseudo-Pythagorean writings go under the name of largely unimportant, or otherwise unknown, authors. Nonetheless, this apocryphal literature considerably contributed to lending the necessary authority to a very influential tradition that extended over the centuries. In this contribution I will endeavour, among other things, to explain (a) how Archytas came to be regarded as a major source of authority; (b) why the authors of Pythagorean forgeries made recourse to names which apparently were anything but authoritative; (c) more broadly, what kind of criteria may have guided the authors in building the pseudo-Pythagorean corpus; (d) what relationship exists between these writings and the Platonist tradition.

In Adversus Colotem (1121F), Plutarch suggests that Colotes – in his polemical work against some of the eminent philosophers up to Epicurus – accused Arcesilaus of attributing his own sceptical views not only to Socrates and Plato but also to Parmenides and Heraclitus. Since Colotes’ list dated back to Arcesilaus’ time, it seems likely that Colotes derived the list from Arcesilaus himself. However, Heraclitus does not figure at all among Arcesilaus’ illustrious predecessors in Cicero’s Academica. This absence is puzzling not only because Heraclitus had a ‘pervasive impact’ upon Plato’s philosophy, and because Arcesilaus strongly appealed to Plato, but also because Heraclitus was a key figure for the Stoics exactly at the time of Arcesilaus and Arcesilaus’ quarrel with the Stoics over their philosophical predecessors. I will set out to detect if and to what extent Arcesilaus made use of Heraclitus in his own philosophy.

In his seminal article on philosophical authority published in 1997, David Sedley showed that, in antiquity, the founder of a philosophical school was taken as figure of ‘authority’ by subsequent members of the school, who would carefully avoid expressing disagreement with him. What is more, the reason for their deference was not purely formal, or political: the authority with which school-members invested the founder of their school was epistemic as well, in the sense that it involved some level of concern to know and be guided by their founder’s views. But this is far from the end of the story. As Jan Opsomer and Angela Ulacco have been careful to describe subsequently, ‘epistemic authority’ ranges widely in sense and strength: from uncritical assent to the truth of whatever can be gleaned from the authority-figure within a given domain, to the belief that their views might help to point one in the right direction.1 Where one stands on this question might make all the difference to the character of one’s philosophical project.