Republic 5:477

"That is. How could that which is not be known?" "We are sufficiently assured of this, then, even if we should examine it from every point of view, that that which entirely^*παντελῶς: cf. μηδαμῇ and 478 D πάντως. Not foreseeing modern philology Plato did not think it necessary to repeat these qualifying adverbs in 478 B ἢ ἀδύνατον καὶ δοξάσαι τὸ μὴ ὄν, which is still sometimes quoted to prove that Plato was "yet" naively unaware of the distinction between is-not-at-all (does not exist) and is-not-this-or-that."is" is entirely knowable, and that which in no way "is" is in every way unknowable." "Most sufficiently." "Good. If a thing, then, is so conditioned as both to be and not to be, would it not lie between that which absolutely and unqualifiedly is and that which in no way is?" "Between." "Then if knowledge pertains to that which is and ignorance of necessity to that which is not, for that which lies between we must seek for something between nescience and science, if such a thing there be." "By all means." "Is there a thing which we call opinion?" "Surely." "Is it a different faculty from science or the same?" "A different." "Then opinion is set over one thing and science over another, each by virtue of its own distinctive power or faculty." "That is so." "May we say, then, that science is naturally related to that which is,^*Apart from the metaphysical question of the relativity of all knowledge, the word ἐπιστήμη in Greek usage connotes certainty, and so Plato and Aristotle always take it. But more specifically that which (always) is, for Plato, is the "idea" which is not subject to change and therefore always is what it is, while a particular material thing subject to change and relativity both is and is not any and every predicate that can be applied to it. And since knowledge in the highest sense is for Plato knowledge of abstract and general ideas, both in his and in our sense of the word idea, knowledge is said to be of that which is. It is uncritical to ignore Plato’s terminology and purpose and to talk condescendingly of his confusing subjective with objective certainty in what follows. to know that and how that which is is? But rather, before we proceed, I think we must draw the following distinctions." "What ones?"

"Shall we say that faculties,^*The history of the word δύναμις has been studied in recent monographs and its various meanings, from potentiality to active power, discriminated. Cf. J. Souilhé, Etude sur le terme δύναμις dans les Dialogues de Platon, Paris, 1919, pp. 96, 163 ff. But Plato makes his simple meaning here quite plain, and it would be irrelevant to bring in modern denunciations of the "old faculty psychology." powers, abilities are a class of entities by virtue of which we and all other things are able to do what we or they are able to do? I mean that sight and hearing, for example, are faculties, if so be that you understand the class or type that I am trying to describe." "I understand," he said. "Hear, then, my notion about them. In a faculty I cannot see any color or shape or similar mark such as those on which in many other cases I fix my eyes in discriminating in my thought one thing from another. But in the case of a faculty I look to one thing only—that to which it is related and what it effects,^*Cf. my note on Simplic. De An. 146. 21, Class. Phil . xvii. p. 143. and it is in this way that I come to call^*Cf. Ion 537 D οὕτω καλῶ τὴν μὲν ἄλλην, τὴν δὲ ἄλλην τέχνην. each one of them a faculty, and that which is related to^*ἐπί: Cf. Parmenides 147 D-E ἕκαστον τῶν ὀνομάτων οὐκ ἐπί τινι καλεῖς; the same thing and accomplishes the same thing I call the same faculty, and that to another I call other. How about you, what is your practice?" "The same," he said. "To return, then, my friend," said I, "to science or true knowledge, do you say that it is a faculty and a power, or in what class do you put it?" "Into this," he said, "the most potent of all^*Cf. Protagoras 352 B, Aristotle Eth. 1145 b 24. faculties." "And opinion—shall we assign it to some other class than faculty." "By no means," he said, "for that by which we are able to opine is nothing else than the faculty of opinion.^*For the various meanings of δόξα Cf. Unity of Plato’s Thought, p. 47 the word δόξα may be used in this neutral, psychological sense; it may be taken unfavorably to denote mere opinion as opposed to knowledge, or favorably when true opinions and beliefs are set in antithesis to the appetites and instincts." "But not long ago you agreed that science and opinion are not identical." "How could any rational man affirm the identity of the infallible with the fallible?"