Ethical theory of Aristippus is identical with that of the Platonic Sokrates in the Protagoras.
That theory is, in point of fact, identical with the theory expounded by the Platonic Sokrates in Plato’s Protagoras. The general features of both are the same. Sokrates there lays it down explicitly, that pleasure per se is always good, and pain per se always evil: that there is no other good (per se) except pleasure and diminution of pain — no other evil (per se) except pain and diminution of pleasure: that there is no other object in life except to live through it as much as possible with pleasures and without pains;[215] but that many pleasures become evil, because they cannot be had without depriving us of greater pleasures or imposing upon us greater pains while many pains become good, because they prevent greater pains or ensure greater pleasures: that the safety of life thus lies in a correct comparison of the more or less in pleasures and pains, and in a selection founded thereupon. In other words, the safety of life depends upon calculating knowledge or prudence, the art or science of measuring.
[215] Plato, Protag. p. 355 A. ἢ ἀρκεῖ ὑμῖν τὸ ἡδέως καταβιῶναι τὸν βίον ἄνευ λυπῶν; εἰ δὲ ἀρκεῖ, καὶ μὴ ἔχετε μηδὲν ἄλλο φάναι εἶναι ἀγαθὸν ἢ κακόν, ὃ μὴ εἰς ταῦτα τελευτᾷ, τὸ μετὰ τοῦτο ἀκούετε.
The exposition of this theory, by the Platonic Sokrates, occupies the latter portion of the Protagoras, from p. 351 to near the conclusion. See below, [ch. xxiii.] of the present work.
The language held by Aristippus to Sokrates, in the Xenophontic dialogue (Memor. ii. 1. 9), is exactly similar to that of the Platonic Sokrates, as above cited — ἐμαυτὸν τάττω εἰς τοὺς βουλομένους ᾗ ῥᾷστά τε καὶ ἥδιστα βιοτεύειν.
Difference in the manner of stating the theory by the two.
The theory here laid down by the Platonic Sokrates is the same as that of Aristippus. The purpose of life is stated almost in the same words by both: by the Platonic Sokrates, and by Aristippus in the Xenophontic dialogue — “to live through with enjoyment and without suffering.” The Platonic Sokrates denies, quite as emphatically as Aristippus, any good or evil, honourable or base, except as representing the result of an intelligent comparison of pleasures and pains. Judicious calculation is postulated by both: pleasures and pains being assumed by both as the only ends of pursuit and avoidance, to which calculation is to be applied. The main difference is, that the prudence, art, or science, required for making this calculation rightly, are put forward by the Platonic Sokrates as the prominent item in his provision for passing through life: whereas, in the scheme of Aristippus, as far as we know it, such accomplished intelligence, though equally recognised and implied, is not equally thrust into the foreground. So it appears at least in the abstract which we possess of his theory; if we had his own exposition of it, perhaps we might find the case otherwise. In that abstract, indeed, we find the writer replying to those who affirmed prudence or knowledge, to be good per se — and maintaining that it is only good by reason of its consequences:[216] that is, that it is not good as End, in the same sense in which pleasure or mitigation, of pain are good. This point of the theory, however, coincides again with the doctrine of the Platonic Sokrates in the Protagoras: where the art of calculation is extolled simply as an indispensable condition to the most precious results of human happiness.
[216] Diog. L. ii. p. 91.
What I say here applies especially to the Protagoras: for I am well aware that in other dialogues the Platonic Sokrates is made to hold different language.[217] But in the Protagoras he defends a theory the same as that of Aristippus, and defends it by an elaborate argument which silences the objections of the Sophist Protagoras; who at first will not admit the unqualified identity of the pleasurable, judiciously estimated and selected, with the good. The general and comprehensive manner in which Plato conceives and expounds the theory, is probably one evidence of his superior philosophical aptitude as compared with Aristippus and his other contemporaries. He enunciates, side by side, and with equal distinctness, the two conditions requisite for his theory of life. 1. The calculating or measuring art. 2. A description of the items to which alone such measurement must be applied — pleasures and pains. — These two together make the full theory. In other dialogues Plato insists equally upon the necessity of knowledge or calculating prudence: but then he is not equally distinct in specifying the items to which such prudence or calculation is to be applied. On the other hand, it is quite possible that Aristippus, in laying out the same theory, may have dwelt with peculiar emphasis upon the other element in the theory: i.e. that while expressly insisting upon pleasures and pains, as the only data to be compared, he may have tacitly assumed the comparing or calculating intelligence, as if it were understood by itself, and did not require to be formally proclaimed.
[217] See chapters [xxiii.], [xxiv.], [xxxii]. of the present work, in which I enter more fully into the differences between the Protagoras, Gorgias, and Philêbus, in respect to this point.