The aversion of Protagoras for dialectic discussion — after causing an interruption of the ethical argument, and an interlude of comment on the poet Simonides — is at length with difficulty overcome, and the argument is then resumed. The question still continues, What is virtue? What are the five different parts of virtue? Yet it is so far altered that Protagoras now admits that the four parts of virtue which Sokrates professed to have shown to be nearly identical, really are tolerably alike: but he nevertheless contends that courage is very different from all of them, repeating his declaration that many men are courageous, but unjust and stupid at the same time. This position Sokrates undertakes to refute. In doing so, he lays out one of the largest, most distinct, and most positive theories of virtue, which can be found in the Platonic writings.
Ethical view given by Sokrates worked out at length clearly. Good and evil consist in right or wrong calculation of pleasures and pains of the agent.
Virtue, according to this theory, consists in a right measurement and choice of pleasures and pains: in deciding correctly, wherever we have an alternative, on which side lies the largest pleasure or the least pain — and choosing the side which presents this balance. To live pleasurably, is pronounced to be good: to live without pleasure or in pain, is evil. Moreover, nothing but pleasure, or comparative mitigation of pain, is good: nothing but pain is evil.[143] Good, is identical with the greatest pleasure or least pain: evil, with greatest pain: meaning thereby each pleasure and each pain when looked at along with its consequences and concomitants. The grand determining cause and condition of virtue is knowledge: the knowledge, science, or art, of correctly measuring the comparative value of different pleasures and pains. Such knowledge (the theory affirms), wherever it is possessed, will be sure to command the whole man, to dictate all his conduct, and to prevail over every temptation of special appetite or aversion. To say that a man who knows on which side the greatest pleasure or the least pain lies, will act against his knowledge — is a mistake. If he acts in this way, it is plain that he does not possess the knowledge, and that he sins through ignorance.
[143] The substantial identity of Good with Pleasure, of Evil with Pain, was the doctrine of the historical Sokrates as declared in Xenophon’s Memorabilia. See, among other passages, i. 6, 8. Τοῦ δὲ μὴ δουλεύειν γαστρὶ μηδὲ ὕπνῳ καὶ λαγνείᾳ, οἴει τι ἄλλο αἰτιώτερον εἶναι, ἢ τὸ ἕτερα ἔχειν τούτων ἡδίω, ἃ οὐ μόνον ἐν χρείᾳ ὄντα εὐφραίνει, ἀλλὰ καὶ ἐλπίδας παρέχοντα ὠφελήσειν ἀεί; Καὶ μὴν τοῦτό γε οἶσθα, ὅτι οἱ μὲν οἰόμενοι μηδὲν εὖ πράττειν οὐκ εὐφραίνονται, οἱ δὲ ἡγούμενοι καλῶς προχωρεῖν ἑαυτοῖς, ἢ γεωργίαν ἢ ναυκληρίαν ἢ ἄλλ’ ὅ, τι ἂν τυγχάνωσιν ἐργαζόμενοι, ὡς εὖ πράττοντες εὐφραίνονται. Οἴει οὖν ἀπὸ πάντων τούτων τοσαύτην ἡδονὴν εἶναι, ὅσην ἀπὸ τοῦ ἑαυτόν τε ἡγεῖσθαι βελτίω γίγνεσθαι καὶ φίλους ἀμείνους κτᾶσθαι; Ἐγὼ τοίνυν διατελῶ ταῦτα νομίζων.
Locke says, ‘Essay on Human Understanding,’ Book ii. ch. 28, “Good or Evil is nothing but pleasure or pain to us — or that which procures pleasure or pain to us. Moral good or evil then is only the conformity or disagreement of our voluntary actions to some law, whereby good or evil is drawn on us by the will and power of the law-maker; which good or evil, pleasure or pain, attending our observance or breach of the law, is that we call reward or punishment.”
The formal distinction here taken by Locke between pleasure and that which procures pleasure — both the one and the other being called Good — (the like in regard to pain and evil) is not distinctly stated by Sokrates in the Protagoras, though he says nothing inconsistent with it: but it is distinctly stated in the Republic, ii. p. 357, where Good is distributed under three heads. 1. That which we desire immediately and for itself — such as Enjoyment, Innocuous pleasure. 2. That which we desire both for itself and for its consequences — health, intelligence, good sight or hearing, &c. 3. That which we do not desire (perhaps even shun) for itself, but which we accept by reason of its consequences in averting greater pains or procuring greater pleasures.
This discrimination of the varieties of Good, given in the Republic, is quite consistent with what is stated by Sokrates in the Protagoras, though it is more full and precise. But it is not consistent with what Sokrates says in the Gorgias, where he asserts a radical dissimilarity of nature between ἡδὺ and ἀγαθόν.
Protagoras is at first opposed to this theory.
Protagoras agrees with Sokrates in the encomiums bestowed on the paramount importance and ascendancy of knowledge: but does not at first agree with him in identifying good with pleasure, and evil with pain. Upon this point, too, he is represented as agreeing in opinion with the Many. He does not admit that to live pleasurably is good, unless where a man takes his pleasure in honourable things. He thinks it safer, and more consistent with his own whole life, to maintain — That pleasurable things, or painful things, may be either good, or evil, or indifferent, according to the particular case.