[45] Plato, Menon, p. 85 E. οὗτος γὰρ (the untaught slave) ποιήσει περὶ πάσης γεωμετρίας ταὐτὰ ταῦτα, καὶ τῶν ἄλλων μαθημάτων ἁπάντων.
The mind of the slave questioned by Sokrates is discovered to be pregnant. Though he has received no teaching from any professed geometer, he is nevertheless found competent, when subjected to a skilful interrogatory, to arrive at last, through a series of mistakes, at correct answers, determining certain simple problems of geometry. He knows nothing about geometry: nevertheless there exist in his mind true opinions respecting that which he does not know. These opinions are “called up like a dream” by the interrogatories: which, if repeated and diversified, convert the opinions into knowledge, taken up by the respondent out of himself.[46] The opinions are inherited from an antecedent life and born with him, since they have never been taught to him during this life.
[46] Plato, Menon, p. 85. τῷ οὐκ εἰδότι ἄρα περὶ ὧν ἂν μὴ εἰδῇ ἔνεισιν ἀληθεῖς δόξαι.… καὶ νῦν μέν γε αὐτῷ ὥσπερ ὄναρ ἄρτι ἀνακεκίνηνται αἱ δόξαι αὗται· εἰ δὲ αὐτόν τις ἀνερήσεται πολλάκις τὰ αὐτὰ ταῦτα καὶ πολλαχῆ, οἶσθ’ ὅτι τελευτῶν οὐδενὸς ἧττον ἀκριβῶς ἐπιστήσεται περὶ αὐτων.… Οὐκοῦν οὐδενὸς διδάξαντος ἀλλ’ ἐρωτήσαντος ἐπιστήσεται, ἀναλαβὼν αὐτὸς ἐξ αὐτοῦ τὴν ἐπιστήμην;
Plato’s theory about pre-natal experience. He took no pains to ascertain and measure the extent of post-natal experience.
It is thus that Plato applies to philosophical theory the doctrine (borrowed from the Pythagoreans) of pre-natal experience and cognitions: which he considers, not as inherent appurtenances of the mind, but as acquisitions made by the mind during various antecedent lives. These ideas (Plato argues) cannot have been acquired during the present life, because the youth has received no special teaching in geometry. But Plato here takes no account of the multiplicity and diversity of experiences gone through, comparisons made, and acquirements lodged, in the mind of a youthful adult however unlettered. He recognises no acquisition of knowledge except through special teaching. So, too, in the Protagoras, we shall find him putting into the mouth of Sokrates the doctrine — That virtue is not taught and cannot be taught, because there were no special masters or times of teaching. But in that dialogue we shall also see Plato furnishing an elaborate reply to this doctrine in the speech of Protagoras; who indicates the multifarious and powerful influences which are perpetually operative, even without special professors, in creating and enforcing ethical sentiment. If Plato had taken pains to study the early life of the untaught slave, with its stock of facts, judgments, comparisons, and inferences suggested by analogy, &c., he might easily have found enough to explain the competence of the slave to answer the questions appearing in the dialogue. And even if enough could not have been found, to afford a direct and specific explanation — we must remember that only a very small proportion of the long series of mental phenomena realised in the infant, the child, the youth, ever comes to be remembered or recorded. To assume that the large unknown remainder would be insufficient, if known, to afford the explanation sought, is neither philosophical nor reasonable. This is assumed in every form of the doctrine of innate ideas: and assumed by Plato here without even trying any explanation to dispense with the hypothesis: simply because the youth interrogated had never received any special instruction in geometry.
Little or nothing is said in the Menon about the Platonic Ideas or Forms.
I have already observed, that though great stress is laid in this dialogue upon the doctrine of opinions and knowledge inherited from an antecedent life — upon the distinction between true opinion and knowledge — and upon the identity of the process of learning with reminiscence — yet nothing is said about universal Ideas or Forms, so much dwelt upon in other dialogues. In the Phædrus and Phædon, it is with these universal Ideas that the mind is affirmed to have had communion during its prior existence, as contrasted with the particulars of sense apprehended during the present life: while in the Menon, the difference pointed out between true opinions and knowledge is something much less marked and decisive. Both the one and the other are said to be, not acquired during this life, but inherited from antecedent life: to be innate, yet unperceived — revived by way of reminiscence and interrogation. True opinions are affirmed to render as much service as knowledge, in reference to practice. There is only this distinction between them — that true opinions are transient, and will not remain in the mind until they are bound in it by causal reasoning, or become knowledge.
What Plato meant by Causal Reasoning — his distinction between knowledge and right opinion.
What Plato meant by this “causal reasoning, or computation of cause,” is not clearly explained. But he affirms very unequivocally, first, that the distinction between true opinion and knowledge is one of the few things of which he feels assured[47] — next, with somewhat less confidence, that the distinction consists only in the greater security which knowledge affords for permanent in-dwelling in the mind. This appears substantially the same distinction as what is laid down in other words towards the close of the dialogue — That those, who have only true opinions and not knowledge, judge rightly without knowing how or why; by an aptitude not their own but supplied to them from without for the occasion, in the nature of inspiration or prophetic œstrus. Hence they are unable to teach others, or to transfer this occasional inspiration to any one else. They cannot give account of what they affect to know, nor answer scrutinizing questions to test it. This power of answering and administering cross-examination, is Plato’s characteristic test of real knowledge — as I have already observed in my eighth chapter.
[47] Plato, Menon, p. 98 B. ὅτι δέ ἐστί τι ἀλλοῖον ὀρθὴ δόξα καὶ ἐπιστήμη, οὐ πάνυ μοι δοκῶ τοῦτο εἰκάζειν· ἀλλ’ εἴπερ τι ἄλλο φαίην ἂν εἰδέναι, ὀλίγα δ’ ἂν φαίην, ἓν δ’ οὖν καὶ τοῦτο ἐκείνων θείην ἂν ὧν οἶδα.