When we read the objection here advanced by Plato (in the above passage of the Republic) as conclusive against the appeal to φρόνησις absolutely (without specifying φρόνησις of what), we are surprised to see that it is not even mentioned in the Philêbus.
Mistake of talking about Bonum confidently, as if it were known, while it is subject of constant dispute. Plato himself wavers about it; gives different explanations, and sometimes professes ignorance, sometimes talks about it confidently.
In this passage of the Republic Plato points out that Intelligence cannot be understood, except as determined by or referring to some Object or End: and that those who tendered Intelligence per se for an explanation of The Good (as Sokrates does in the Philêbus), assumed as known the very point in dispute which they professed to explain. This is an important remark in regard to ethical discussions: and it were to be wished that Plato had himself avoided the mistake which he here blames in others. The Platonic Sokrates frequently tells us that he does not know what Good is. In the sixth Book of the Republic, having come to a point where his argument required him to furnish a positive explanation of it, he expressly declines the obligation and makes his escape amidst the clouds of metaphor.[103] In the Protagoras, he pronounces Good to be identical with pleasure and avoidance of pain, in the largest sense and under the supervision of calculating Intelligence.[104] In the second Book of the Republic, we find what is substantially the same explanation as that of the Protagoras, given (though in a more enlarged and analytical manner) by Glaukon and assented to by Sokrates; to the effect that Good is tripartite,[105] viz.: 1. That which we desire for itself, without any reference to consequences — e. g., enjoyment and the innocuous pleasures. 2. That which we desire on a double account, both for itself and by reason of its consequences — e. g., good health, eyesight, intelligence, &c. 3. That which we do not desire, perhaps even shun, for itself: but which we desire, or at least accept, by reason of its consequences — such as gymnastics, medical treatment, discipline, &c. Again, in the Gorgias and elsewhere, Plato seems to confine the definition of Good to the two last of these three heads, rejecting the first: for he distinguishes pointedly the Good from the Pleasurable. Yet while thus wavering in his conception of the term, Plato often admits it into the discussions as if it were not merely familiar, but clear and well-understood by every one.
[103] Plato, Republic, vi. p. 506 E.
Compare also Republic, vii. p. 533 C. ᾦ γὰρ ἀρχὴ μὲν ὃ μὴ οἶδε, τελευτὴ δὲ καὶ τὰ μεταξὺ ἐξ οὖ μὴ οἶδε συμπέπλεκται, τίς μηχανὴ τὴν τοιαῦτην ὁμολογίαν ποτὲ ἐπιστήμην γίγνεσθαι;
[104] Plato, Protagoras, pp. 356-7.
[105] Plato, Republic, ii. p. 357 B.
Plato lays down tests by which Bonum may be determined: but the answer in the Philêbus does not satisfy those tests.
In the present dialogue, Plato lays down certain characteristic marks whereby The Supreme Good may be known. These marks are subjective — relative to the feelings and appreciation of sentient beings — to all mankind, and even to animals and plants. Good is explicitly defined by the property of conferring happiness. The Good is declared to be “that habit and disposition of mind which has power to confer on all men a happy life”:[106] it is perfect and all sufficient: every creature that knows Good, desires and hunts after it, demanding nothing farther when it is attained, and caring for nothing else except what is attained along with it:[107] it is the object of choice for all plants and animals, and if any one prefers any thing else, he only does so through ignorance or from some untoward necessity:[108] it is most delightful and agreeable to all.[109] This is what Plato tells us as to the characteristic attributes of Good. And the test which Sokrates applies, to determine whether Pleasure does or does not correspond with these attributes, is an appeal to individual choice or judgment. “Would you choose? Would any one be satisfied?” Though this appeal ought by the conditions of the problem to be made to mankind generally, and is actually made to Protarchus as one specimen of them — yet Sokrates says at the end of the dialogue that all except philosophers choose wrong, being too ignorant or misguided to choose aright. Now it is certain that what these philosophers choose, will not satisfy the aspirations of all other persons besides. It may be Good, in reference to the philosophers themselves: but it will fail to answer those larger conditions which Plato has just laid down.
[106] Plato, Philêbus, p. 11 E.