Plato, Republic

[478a] that opinion is a different¹ thing from scientific knowledge.” “Yes, different.” “Each of them, then, since it has a different power, is related to a different object.” “Of necessity.” “Science, I presume, to that which is, to know the condition of that which is. But opinion, we say, opines.” “Yes.” “Does it opine the same thing that science knows, and will the knowable and the opinable be identical, or is that impossible?” “Impossible by our admissions,²” he said. “If different faculties are naturally related to different objects [478b] and both opinion and science are faculties, but each different from the other, as we say—these admissions do not leave place for the identity of the knowable and the opinable.” “Then, if that which is is knowable, something other than that which is would be the opinable.³” “Something else.” “Does it opine that which is not,⁴ or is it impossible even to opine that which is not? Reflect: Does not he who opines bring his opinion to bear upon something or shall we reverse ourselves and say that it is possible to opine, yet opine nothing?” “That is impossible.” “Then he who opines opines some one thing.” “Yes.” “But surely that which is not could not be designated as some one thing, but [478c] most rightly as nothing at all. To that which is not we of necessity assigned nescience, and to that which is, knowledge.” “Rightly,” he said. “Then neither that which is nor that which is not is the object of opinion.” “It seems not.” “Then opinion would be neither nescience nor knowledge.” “So it seems.” “Is it then a faculty outside of these, exceeding either knowledge in lucidity or ignorance in obscurity?” “It is neither.” “But do you deem opinion something darker than knowledge but brighter than ignorance?” “Much so,” he said. “And does it lie within the boundaries [478d] of the two?” “Yes.” “Then opinion would be between the two.” “Most assuredly.” “Were we not saying a little while ago⁵ that if anything should turn up⁶ such that it both is and is not, that sort of thing would lie between that which purely and absolutely is and that which wholly is not, and that the faculty correlated with it would be neither science or nescience, but that which should appear to hold a place correspondingly between nescience and science.” “Right.” “And now there has turned up between these two the thing that we call opinion.” “There has.” [478e]

“It would remain, then, as it seems, for us to discover that which partakes of both, of to be and not to be, and that could not be rightly designated either in its exclusive purity; so that, if it shall be discovered, we may justly pronounce it to be the opinable, thus assigning extremes to extremes and the intermediate to the intermediate. Is not that so?” “It is.” “This much premised, let him tell me,