But even if cognition of cognition be possible, I shall not admit it as an explanation of what temperance is, until I have satisfied myself that it is beneficial. For I have a presentiment that temperance must be something beneficial and good.[19]
[19] Plato, Charm. 169 B. ὠφελιμόν τι κἀγαθὸν μαντεύομαι εἶναι.
Even if cognition of cognition were possible, cognition of non-cognition would be impossible. A man may know what he knows, but he cannot know what he is ignorant of. He knows the fact that he knows: but he does not know how much he knows, and how much he does not know.
Let us concede for the present discussion (continues Sokrates) that cognition of cognition is possible. Still how does this prove that there can be cognition of non-cognition? that a man can know both what he knows and what he does not know? For this is what we declared self-knowledge and temperance to be.[20] To have cognition of cognition is one thing: to have cognition of non-cognition is a different thing, not necessarily connected with it. If you have cognition of cognition, you will be enabled to distinguish that which is cognition from that which is not — but no more. Now the knowledge or ignorance of the matter of health is known by medical science: that of justice known by political science. The knowledge of knowledge simply — cognition of cognition — is different from both. The person who possesses this last only, without knowing either medicine or politics, will become aware that he knows something and possesses some sort of knowledge, and will be able to verify so much with regard to others. But what it is that he himself knows, or that others know, he will not thereby be enabled to find out: he will not distinguish whether that which is known belong to physiology or to politics; to do this, special acquirements are needed. You, a temperate man therefore, as such, do not know what you know and what you do not know; you know the bare fact, that you know and that you do not know. You will not be competent to cross-examine any one who professes to know medicine or any other particular subject, so as to ascertain whether the man really possesses what he pretends to possess. There will be no point in common between you and him. You, as a temperate man, possess cognition of cognition, but you do not know any special cognitum: the special man knows his own special cognitum but is a stranger to cognition generally. You cannot question him, nor criticise what he says or performs, in his own specialty — for of that you are ignorant:— no one can do it except some fellow expert. You can ascertain that he possesses some knowledge: but whether he possesses that particular knowledge to which he lays claim, or whether he falsely pretends to it, you cannot ascertain:— since, as a temperate man, you know only cognition and non-cognition generally. To ascertain this point, you must be not only a temperate man, but a man of special cognition besides.[21] You can question and test no one, except another temperate man like yourself.
[20] Plato, Charm. 169 D. νῦν μὲν τοῦτο ξυγχωρήσωμεν, δυνατὸν εἶναι, γενέσθαι ἐπιστήμην ἐπιστήμης — ἴθι δὴ οὖν, εἰ ὅ, τι μάλιστα δυνατὸν τοῦτο, τί μᾶλλον οἷόν τέ ἐστιν εἰδέναι ἅ τέ τις οἶδε καὶ ἃ μή; τοῦτο γὰρ δήπου ἔφαμεν εἶναι τὸ γιγνώσκειν αὑτὸν καὶ σωφρονεῖν.
[21] Plato, Charm. 170-171. 171 C: Παντὸς ἄρα μᾶλλον, εἰ ἡ σωφροσύνη ἐπιστήμης ἐπιστήμη μόνον ἐστὶ καὶ ἀνεπιστημοσύνης, οὖτε ἰατρὸν διακρῖναι οἵα τε ἔσται ἐπιστάμενον τὰ τῆς τέχνης, ἢ μὴ ἐπιστάμενον προσποιούμενον δὲ ἢ οἰόμενον, οὔτε ἄλλον οὐδένα τῶν ἐπισταμένων καὶ ὁτιοῦν, πλήν γε τὸν αὑτοῦ ὁμότεχνον, ὥσπερ οἱ ἄλλοι δημιουργοί.
Temperance, therefore, as thus defined, would be of little or no value.
But if this be all that temperance can do, of what use is it to us (continues Sokrates)? It is indeed a great benefit to know how much we know, and how much we do not know: it is also a great benefit to know respecting others, how much they know, and how much they do not know. If thus instructed, we should make fewer mistakes: we should do by ourselves only what we knew how to do, — we should commit to others that which they knew how to do, and which we did not know. But temperance (meaning thereby cognition of cognition and of non-cognition generally) does not confer such instruction, nor have we found any science which does.[22] How temperance benefits us, does not yet appear.
[22] Plato, Charm. 172 A. ὁρᾷς, ὅτι οὐδαμοῦ ἐπιστήμη οὐδεμία τοιαύτη οὖσα πέφανται.
But even granting the possibility of that which has just been denied, still Temperance would be of little value. Suppose that all separate work were well performed, by special practitioners, we should not attain our end — Happiness.