In the introduction to the Parmenides Cephalus tells us that he came to Athens (from Clazomenae in Asia Minor) with his friends ‘much interested in philosophy’ (mala philosophoi, 126b8), for they learnt that Antiphon (Plato’s half-brother) often heard (pollakis akousas) from Zeno’s friend Pythodorus the arguments (tous logous) that Socrates, Zeno, and Parmenides once exchanged, so that he remembers them. Adeimantus (Plato’s brother) confirms it as true (alêthê), ‘for he rehearsed the arguments diligently when he was a youngster' (meirakion gar ȏn autous eu mala diemeletêsen, 126b8-c7). This indicates the historicity of that ancient discussion. Socrates was nineteen, Parmenides about 65, and Zeno about 40 when the discussion took place (see R. E. Allen, Plato’s Parmenides, Yale University Press 1997, p. 72).
We are nevertheless not to expect that the discussion is going to be as Antiphon remembered it; he himself ‘was at first reluctant’ (to men prȏton ȏknei) to recall the arguments, ‘for he said it was an arduous task’ (polu gar ephê ergon einai, 127a6), and yet the discussion is narrated by Cephalus who heard Antiphon’s recollections only once. If we pay attention to the way in which the discussion is structured and how Antiphon himself is characterized, we may get an idea of what we are to see as historical in Cephalos’ narrative.
In the opening part of the dialogue we learn that Zeno, a disciple of Parmenides, was reading his treatise to an interested audience. Socrates opened the discussion by conjecturing that Zeno wrote the piece to defend Parmenides’ thesis that ‘All is one’ (hen einai to pan, 128a8-b1), and that he did so by pointing to absurd contradictions in which things would be involved, if they were many. Socrates did not find it surprising that things apprehended by our senses are affected by many contradictions, but said he would be surprized, if Zeno distinguished and set apart the Forms of things alone by themselves (diairêtai chȏris auta kath’ hauta ta eidê, 129d7-8), such as similarity and dissimilarity (hoion homoiotêta kai anomiotêta), many and the one (plêthos kai to hen), rest and motion (stasin kai kinêsin), and show (apophainêi) that these in themselves (en heautois tauta) can both mix together and separate one from another (dunamena sunkerannusthai kai diakrinesthai), getting entangled in exactly the same perplexity (tên autên tautên aporian, 129e6) ‘as the things which we can see and of which you were speaking’ (hȏsper en tois horȏmenois diêlthete – Zeno in his treatise, Parmenides in his poem). (129d6-130a2)
Pythodorus and the other members in the audience thought that Parmenides and Zeno would be annoyed at every word of Socrates (oiesthai eph’ hekastou achthesthai ton te Parmenidên kai Zênȏna, 130a2-5); Socrates’ suggestion that there is a plurality of things free of contradictions threatened Parmenides’ ‘All is one’ thesis. To their surprise, the two listened to Socrates with admiration. Parmenides told him: ‘I admire your eagerness to get engaged in argument (hȏs axios ei agasthai tês hormês tês epi tous logous). And tell me, did you yourself thus distinguish (autos su houtô diêresai), as you say (hôs legeis), apart some ideas in themselves (chôris men eidê atta), and apart the things that partake in them (chôris de ta toutôn au metechonta)? And do you think that likeness itself is something (kai ti soi dokei einai autê homoiotês) apart from the likeness which we have (chȏris hês hêmeis homiotêtos echomen), and one and many (kai hen dê kai polla), and all those things you just heard Zeno mention (kai panta hosa nun Zênȏnos êkoues)?’ Socrates replied: ‘I do think so (Emoige).’ (130a8-b6)
Without pressing the question whether Socrates himself distinguished the Forms as separate from things participating in them Parmenides subjected the theory of Forms to questioning, refuting both the arguments on the basis of which Socrates conceived the Forms and the arguments he invented in the course of the discussion. But then they arrived at a turning point. Parmenides told Socrates: ‘Rest assured that you’ve hardly yet even begun to grasp how great are the difficulties (hosê estin hê aporia) if you always posit one Form by demarcating each class of things (ei hen eidos hekaston tȏn ontȏn aei ti aphorizomenos thêseis) … If someone argued that the Forms (ta eidê) cannot even be known (mêde prosêkei auta gignȏskesthai), if they are as we say they ought to be, no one could show (ouk an echoi tis endeixasthai) to the disputant (tȏi tauta legonti) that he was wrong (hoti pseudetai) unless he happened to be a man of wide experience (ei mê pollȏn men tuchoi empeiros ȏn) and natural ability (kai mê aphuês), willing to follow a man who would show him the Forms in the course of a long preoccupation, beginning from a far (etheloi de panu polla kai porrȏthen pragmateuomenou tou endeiknumenou hepesthai); otherwise there would be no way of convincing a man who would be forcing the Forms to be unknowable.’ (133a11-c1)
Who is supposed to be ‘the man who would show the disputant the Forms in the course of a long preoccupation, beginning from a far’, and what is that preoccupation supposed to be? Plato’s brothers Adeimantus and Glaucon point us in the right direction, for they play an important role in Plato’s Republic. It is at their insistence that Socrates was compelled to transcend his philosophic ignorance in the Republic (357a-368c) by focussing on the embodiment of the Form of Justice, the ideal state. In the Republic Plato describes the road to the Forms in detail, comprehensively and powerfully.
When we realize that Plato dramatically staged the Parmenides so as to direct the reader’s mind towards the Republic, we can properly appreciate the significance of the brief characterization of Antiphon: ‘when Antiphon was young, he diligently and thoroughly rehearsed the arguments, though now, like his grandfather of the same name, he spends most of his time on horses’. As a youngster, Antiphon delighted in arguments against the Forms: ‘Youngsters, when they first get the taste for arguments (hotan to prȏton logȏn geuȏntai), they misuse them for play (hȏs paidiai autois katachrȏntai), always employing them to effect contradiction (aei eis antilogian chrȏmenoi)’, Socrates tells Glaucon in Republic 539b2-5. Arguments against the Forms could not generate in Antiphon a lasting commitment to philosophy, but he must have delighted in diligently rehearsing them and thus annoying Plato, his older half-brother, who by then, in my view, had embraced the Forms. (I’ve argued in The Lost Plato – on my website – that Plato conceived the Forms in his early twenties.) By characterizing Antiphon as he does, Plato indicates that we should view Parmenides’ arguing against the Forms as historical.