Nicomachean Ethics

​Understanding and good understanding, by virtue of which we call people understanding and having good understanding, are neither entirely the same as scientific knowledge or opinion (for then everyone would be understanding) nor any one of the specific sciences, such as medicine concerning healthy things, or geometry concerning magnitudes. For understanding is neither about things that always are and are unchangeable, nor about any of the things that come to be, but rather about those things concerning which one might be perplexed and deliberate. Therefore, though it is about the same things as practical wisdom, understanding and practical wisdom are not the same. For practical wisdom is prescriptive—for its end is what one ought to do or not to do—whereas understanding is only critical. For understanding and good understanding, and understanding people and people of good understanding, are the same. And understanding is neither the possessing of practical wisdom nor the acquiring of it; but just as learning is called understanding when one makes use of scientific knowledge, so in making use of opinion for the purpose of judging about those things with which practical wisdom is concerned, when someone else speaks, and judging well—for ‘well’ is the same as ‘finely’. And from this has come the name ‘understanding’, by virtue of which people have good understanding, from the use of the term in learning; for we often call learning ‘understanding’.

​What is called judgment, by virtue of which we say people are sympathetic and have judgment, is the correct judging of the equitable man. This is indicated by the fact that we say the equitable man is especially sympathetic, and that to have sympathy about certain things is equitable. And sympathy is correct critical judgment of what is equitable; and correct is that which is of the truth. And all these states reasonably tend toward the same point; for we speak of judgment, understanding, practical wisdom, and intellect, attributing to the same people that they already have judgment and intellect, and are practically wise and understanding. For all these faculties are of the extremes and of particulars; and in being critical about the things with which the practically wise man is concerned, one is understanding and of good judgment or sympathetic. For equitable things are common to all good things in relation to another. And all actionable things are of particulars and extremes; for indeed the practically wise man must know them, and both understanding and judgment are about actionable things, and these are extremes. And intellect is of the extremes in both directions; for both the first terms and the last are of intellect and not of a rational account; and while the intellect in demonstrations is of the unchangeable and first terms, the intellect in practical matters is of the extreme, the contingent, and the minor premise. For these particulars are the starting points of that for the sake of which; for from particulars come universals. Of these, therefore, one must have perception, and this perception is intellect. Hence these are also thought to be natural, and though no one is wise by nature, people are thought to have judgment, understanding, and intellect by nature. This is indicated by our thinking that they accompany ages, and that this particular age has intellect and judgment, as if nature were the cause. Therefore we ought to attend to the undemonstrated assertions and opinions of experienced and older people or of the practically wise, no less than to demonstrations; for because they have an eye from experience, they see correctly. What, then, practical wisdom and wisdom are, and about what each happens to be, and that each is the virtue of a different part of the soul, has been said.