[37] Plato, Menon, p. 80 A. νάρκη θαλασσία. Compare what I have said above about the Ion, [ch. XVII., p. 128].
[38] Plato, Menon, p. 80 D.
Great question discussed among the Grecian philosophers — criterion of truth — Wherein consists the process of verification?
Here we find explicitly raised, for the first time, that difficulty which embarrassed the different philosophical schools in Greece for the subsequent three centuries — What is the criterion of truth? Wherein consists the process called verification and proof, of that which is first presented as an hypothesis? This was one of the great problems debated between the Academics, the Stoics, and the Sceptics, until the extinction of the schools of philosophy.[39]
[39] Sokrates here calls this problem an ἐριστικὸς λόγος. Stallbaum (in his Prolegom. to the Menon, p. 14) describes it as a “quæstiunculam, haud dubie e sophistarum disciplinâ arreptam”. If the Sophists were the first to raise this question, I think that by doing so they rendered service to the interests of philosophy. The question is among the first which ought to be thoroughly debated and sifted, if we are to have a body of “reasoned truth“ called philosophy.
I dissent from the opinion of Stallbaum (p. 20), though it is adopted both by Socher (Ueber Platon, p. 185) and by Steinhart (Einleitung zum Menon, p. 123), that the Menon was composed by Plato during the lifetime of Sokrates. Schleiermacher (Einleitung zum Gorgias, p. 22; Einleitung zum Menon, pp. 329-330), Ueberweg (Aechth. Plat. Schr. p. 226), and K. F. Hermann, on the other hand, regard the Menon as composed after the death of Sokrates, and on this point I agree with them, though whether it was composed not long after that event (as K. F. Hermann thinks) or thirteen years after it (as Schleiermacher thinks), I see no sufficient grounds for deciding. I incline to the belief that its composition is considerably later than Hermann supposes; the mention of the Theban Ismenias is one among the reasons rendering such later origin probable. Plato probably borrowed from the Xenophontic Anabasis the name, country, and social position of Menon, who may have received teaching from Gorgias, as we know that Proxenus did, Xen. Anab. ii. 6, 16. The reader can compare the Einleitung of Schleiermacher (in which he professes to prove that the Menon is a corollary to the Theætêtus and Gorgias, and an immediate antecedent to the Euthydêmus, — that it solves the riddle of the Protagoras — and that it presupposes and refers back to the Phædrus) with the Einleitung of Steinhart (p. 120 seq.), who contests all these propositions, saying that the Menon is decidedly later than the Euthydêmus, and decidedly earlier than the Theætêtus, Gorgias, and Phædrus; with the opinions of Stallbaum and Hermann, who recognise an order different from that either of Steinhart or Schleiermacher; and with that of Ast, who rejects the Menon altogether as unworthy of Plato. Every one of these dissentient critics has something to say for his opinion, while none of them (in my judgment) can make out anything like a conclusive case. The mistake consists in assuming that there must have been a peremptory order and intentional interdependence among the Platonic Dialogues, and next in trying to show by internal evidence what that order was.
None of the philosophers were satisfied with the answer here made by Plato — that verification consists in appeal to pre-natal experience.
Not one of these schools was satisfied with the very peculiar answer which the Platonic Sokrates here gives to the question. When truth is presented to us (he intimates), we recognise it as an old friend after a long absence. We know it by reason of its conformity to our antecedent, pre-natal, experience (in the Phædon, such pre-natal experience is restricted to commerce with the substantial, intelligible, Ideas, which are not mentioned in the Menon): the soul or mind is immortal, has gone through an indefinite succession of temporary lives prior to the present, and will go through an indefinite succession of temporary lives posterior to the present — “longæ, canitis si cognita, vitæ Mors media est“. The mind has thus become omniscient, having seen, heard, and learnt every thing, both on earth and in Hades: but such knowledge exists as a confused and unavailable mass, having been buried and forgotten on the commencement of its actual life.
Since all nature is in universal kindred, communion, or interdependence, that which we hear or see here, recalls to the memory, by association, portions of our prior forgotten omniscience.[40] It is in this recall or reminiscence that search, learning, acquisition of knowledge, consists. Teaching and learning are words without meaning: the only process really instructive is that of dialectic debate, which, if indefatigably prosecuted, will dig out the omniscience buried within.[41] So vast is the theory generated in Plato’s mind, by his worship of dialectic, respecting that process of search to which more than half of his dialogues are devoted.
[40] The doctrine of communion or interdependence pervading all Nature, with one continuous cosmical soul penetrating everywhere, will be found set forth in the kosmology of the Timæus, pp. 37-42-43. It was held, with various modifications, both by the Pythagoreans and the Stoics. Compare Cicero, Divinat. ii. 14-15; Virgil, Æneid vi. 715 seqq.; Georgic. iv. 220; Sextus Empir. adv. Mathem. ix. 127; Ekphantus Pythagoreus ap. Stobæum, Tit. 48, vol. ii. p. 320, Gaisford.