Aristotle’s Conception of Practical Truth and the Consequences of that Conception

by Mortimer J. Adler, Ph.D.

My interest in the subject I have chosen for this essay goes beyond the importance of the subject itself. Its importance cannot be overestimated. Aristotle’s conception of practical truth should control our interpretation of the Ethics as a whole, understanding it as a moral philosophy that is not simply teleological and pragmatic (which is the interpretation that has prevailed in many quarters from Kant onward), but is basically a deontological ethics, whose first principle is the self-evident statement of a categorical obligation. Beyond that, my interest lies in the fact that Aristotle’s definition of practical truth, had it been known to and understood by contemporary analytic and linguistic philosophers, would have saved them from preoccupation with a pseudo-problem and from espousing the solution of it that they adopted with disastrous consequences for the status of ethics — regarding it as non-cognitive rather than as a body of knowledge, i.e., a set of principles and conclusions that can lay claim to being true.

That there is such widespread ignorance of Aristotle’s introduction of a two-fold conception of truth, sharply distinguishing between the truth of theoretical (or descriptive) statements on the one hand, and the truth of practical (or normative) statements on the other hand, can, perhaps, be explained, though hardly excused, by the fact that his treatment of this crucial matter is contained in a single paragraph in Book VI, Chapter 2 of the Ethics (1139a2l-31). The distinguishing characteristic of practical truth is formulated in five words at the end of that paragraph. To my knowledge, the matter considered in that one paragraph and the formulation contained in those five words is not mentioned anywhere else in the Aristotelian corpus. Hence a reader of Aristotle who is not attentive to the one brief appearance of this discussion and does not pause to ponder its full significance for the rest of the Ethics will be ignorant of the point and will inevitably misinterpret the rest of the book. What I have just said holds not only for the analytical and linguistic philosophers who have probably not read Aristotle carefully, if at all, but also for Kant, John Stuart Mill, and a host of Oxford commentators on the Ethics who have certainly read the book but who seemed to have missed or ignored the point under consideration.

The formulation Aristotle advances in the last five words of the paragraph cited calls for an extended explanation. Aristotle himself nowhere tells us what he means by “right desire” (a phrase which occurs in the body of the paragraph and in its last five words), nor does he develop the implications of what is meant by that phrase. However, we are given some help in doing that for ourselves by a few brief statements elsewhere in his works, specifically in the opening sentence of the Metaphysics, in the opening sentence of the Ethics, in distinctions that are developed only in Book III, Chapter 4, of the Ethics, and in two paragraphs of the chapter that follows (1114a32-1114b25), confirmed by what is implied by several statements made in Book X, Chapter 5 (esp. the two sentences at 1176al5-19). Aristotle does not call our attention to the bearing of the passages just cited on the conception of practical truth presented in Ethics, VI, 2. Yet their bearing is crucial. Without the light they throw on the meaning of “right desire,” it is impossible, in my judgment, to understand what makes some desires right and others wrong; and unless we can understand that, what sense can we make of the statement that, whereas the truth of theoretical or descriptive statements (containing some form of “is” or “is not”) consists in their agreement with reality (with what is or is not), the truth of practical or normative statements (containing some form of “ought” or “ought not”) consists in their agreement with right desire?

If the few passages mentioned are so important, it may be wondered why Aristotle treated the observations and distinctions they contain so briefly, almost glancingly. Why did he not call explicit attention to how the several points being made therein are related to one another in a single comprehensive doctrine that should control our understanding of the Ethics as a whole? Why is that doctrine nowhere explicitly stated? The only answer that occurs to me is that Aristotle must have assumed that the audience to which he was lecturing already understood the unstated doctrine, that it was part of the accepted wisdom in his day, shared by students in the Academy and the Lyceum, and that a mere mention of the points involved therefore sufficed.

Sound as it may have been in the 4th century B. C., that assumption does not hold for modern students from the 17th century on, including here the leading representatives of modern philosophy. No wonder, then, that the Ethics is so generally misunderstood — so generally commented on, either adversely or favorably, for doctrines it does not advance. No wonder that its central, controlling insights have gone completely unnoticed in this literature of commentary. No wonder that the exponents of the contemporary view that ethics must be non-cognitive would appear to be able to make out a strong case for that false position.

With these preliminary observations, I will proceed as follows: first, to indicate why ignorance of Aristotle’s conception of practical truth allows a strong case to be made for the view that ethics must be non-cognitive; second, to show how two distinctions that Aristotle assumed were generally understood by his audience permitted him to assume that his audience would also readily understand what he meant by “right desire”; and third, to summarize briefly the central doctrine that emerges from these considerations, a doctrine that should control our understanding of the Ethics as a whole.


The view that ethics is non-cognitive was advanced at about the same time by A. J. Ayer (Language, Truth, and Logic, 1946), R. M. Hare (The Language of Morals, 1952), and C. L. Stevenson (Ethics and Language, 1944). Earlier in the century, Bertrand Russell had encapsulated this view in a quip that ran somewhat as follows: “Ethics is the art of recommending to others what they should do in order to get along with one’s self.” Since the different views of what a non-cognitive ethics consists in are of no interest to us, I will confine my attention to the reasons that Ayer gave for thinking that ethics must be non-cognitive.

For Ayer, only sentences that make statements (i.e., sentences that are declarative in mood, not imperative, subjunctive, or interrogative) can be either true or false. Aristotle made the same point somewhat earlier (On Interpretation, Ch. 4). The propositions expressed by declarative sentences can possess one or another of the only two sorts of truth with which Ayer is acquainted (a) on the one hand, the kind of a priori, verbal or logical truth that is to be found in analytical propositions; (b) on the other hand, the kind of a posteriori, empirically verifiable truth that is to be found in propositions stating matters of fact. In the latter case, what is truly stated is a description of the way things are. So far as all a posteriori descriptive propositions go, Ayer does not appear to part company with Aristotle’s statement that the truth of such propositions consists in their asserting that that which is, is and that which is not, is not (Metaphysics, IV, 7, 1011b27-29). For Ayer, of course, analytical propositions are all of the sort that Locke called “trivial” and “uninstructive,” whereas for Aristotle, axioms, or selfevident first principles, are far from being trivial or uninstructive. This is a difference I shall return to presently.

Statements that contain such words as “good” and “bad,” “right” and “wrong,” “ought” and “ought not,” and that cannot be somehow reduced to descriptive statements of fact, are clearly incapable of having the truth or falsity that is appropriate to descriptive statements. With that observation, neither Aristotle nor anyone else can cavil. If statements do not assert that something is or is not, the truth of such statements cannot consist in their agreeing with what is or is not the case. According to Ayer, they must be regarded as expressions of emotion or as commands that are designed to provoke action of a certain sort.

Ayer then goes further. Sentences that contain the words indicated above and that cannot be interpreted as descriptive, he regards as not making any sort of statement.

If a sentence makes no statement at all, there is obviously no sense in asking whether what it says is true or false. And we have seen sentences which simply express moral judgments, or do not say anything. They are purely expressions of feeling and as such do not come under the category of truth and falsehood. They are unverifiable for the same reasons as a cry of pain or a word of command is unverifiable — because they do not express genuine propositions (op. cit., p. 103).

In saying this, Ayer goes further than he needs to go in order to support his thesis that ethics is non-cognitive. There is no ground for saying that the sentence “Human beings ought to seek knowledge” asserts nothing. The fact that the statement it makes is normative (an “ought” statement) rather than descriptive (an “is” statement) does not justify Ayer in dismissing the sentence as not making an assertion or statement.

However, the pivotal question still remains unanswered. Granted that a declarative sentence is not precluded from making a statement or expressing a proposition because it contains the word “ought” rather than the word “is,” how can normative propositions be true if the only kind of truth is the one kind that is exclusively appropriate to descriptive propositions, i.e., the kind of truth defined in Metaphysics, IV, 7? Nowhere in the discussion of truth in Metaphysics, IV, does Aristotle hint that there may be another kind of truth; nor in On Interpretation, 4, where he separates declarative from all other types of sentences, does he suggest that declarative sentences may be subdivided into two sub-types — “is” sentences and “ought” sentences.

Hence, if Ayer’s reading of Aristotle were confined to the Metaphysics and On Interpretation, he would be justified in citing Aristotle in support of the view that ethics — at least to the extent that it contains normative judgments or “ought” propositions — must be non-cognitive; for Aristotle does not appear to acknowledge “ought” sentences as declarative and, even if he did, his theory of truth would not apply to normative judgments or “ought” propositions. If there is only one kind of truth, and if that kind consists in asserting what in fact is or is not the case, then statements which assert that something ought or ought not to be the case can be neither true nor false.

If, however, Ayer and others who share his view of ethics as noncognitive, had read and tried to understand that one brief paragraph in Ethics, VI, 2, he and they might never have raised the question about how normative propositions can be true or false. Ayer and the others certainly proceed as if that question had never been raised before and as if no one had ever proposed an answer to it. But since the brief statement that practical truth consists in the agreement of a normative judgment with right desire does not explain itself, and since the explanation of it is not immediately apparent, mere acquaintance with that text on the part of Ayer and others would probably have made little difference to their thinking.


What is right desire? The answer must be that right desire consists in desiring what one ought to desire. What ought one to desire? The answer cannot be — simply and without qualification — that we ought to desire what is good. Aristotle tells us in the opening paragraph of the Ethics that voluntary actions, springing from desires, always aim at the good. Hence if the good is always and only the desirable, and the desirable is always and only the good, there must be some difference between the good that we wrongly desire and the good that we rightly desire.

That difference is to be found in the distinction between the real and the apparent good, a distinction that was part of the accepted wisdom in the Academy. Socrates repeatedly calls attention (as in Plato’s Meno, 77a-d) to the fact that whatever we desire appears good to us because we desire it, but that fact does not make it really good for us. If the good were always and only that which appears good to us because we actually and consciously desire it, how could there be a difference between right and wrong desire? That which is really good for us must be something we ought to desire whether, in fact, we actually and consciously desire it. The desire must include both that which we ought to desire because it is really good for us and that which appears good to us because we actually and consciously desire it.

In the Ethics, III, 4-5, Aristotle relates the distinction between the real and the apparent good to the distinction between two kinds of desire: on the one hand, the desires that are inherent in our common human nature, rooted in potentialities or capacities that seek fulfillment; and, on the other hand, desires that we acquire in the course of, and as the result of, our individual experience. Our natural desires are always present in us and are operative tendentially or appetitively whether we are conscious of them or not. In contrast, we are always conscious of our individual, acquired desires when they are operative. Furthermore, only the latter belong to the sphere of the voluntary or volitional.

In Ethics, III, 4, Aristotle says that while the good is the object of desire for every man, “that which is in truth an object of desire is an object of desire to the good man, while any chance thing may be so to the bad man.” This follows the statement that “those who say that the good is the object of desire must admit in consequence that that which the man who does not choose aright desires is not an object of desire (for if it is to be so, it must also be good; but it was, as it happened, bad); while those who say the apparent good is the object of desire must admit that there is no natural object of desire, but only what appears good to each man. Now different things appear good to different people and, as it happens, even contrary things.” There is no way to avoid those consequences, Aristotle warns us, unless we distinguish between the real good (the good aimed at by our natural, inborn appetitive tendencies) and the apparent good (that which appears good to us simply because of some acquired desire that has become operative and of which we are conscious).

That which we actually and consciously desire may, of course, be the good that is aimed at by our inborn appetitive tendencies. In other words, that which is really good may also appear good to the man who actually and consciously desires it. The man who actually desires what is really good for him according to his natural appetites is one who desires aright, one who desires what he ought to desire. He is the good or virtuous man, for to be virtuous is to have the habit of right desire in the act of choice. As Aristotle says, in Ethics, X, 5, “that which appears good to the good man is really so.”

Let me substitute the English words “needs” and “wants” to designate natural desires, on the one hand, and acquired desires, on the other. The goods aimed at by our needs are the things that are really good for us. The goods we want always appear good to us when — and because — we want them, but they may be really bad for us. Since our needs do not belong to the sphere of the voluntary or volitional, we cannot say that we ought or ought not to need something; we cannot say that a need is right or wrong. That can be said only of our wants, which belong to the sphere of the voluntary or volitional. Our wants can be right or wrong: right if they aim at that which is really good for us, either good in itself or good because they facilitate our attaining that which is really good for us. Similarly, our wants can be wrong: wrong if they aim at that which is really bad for us, either bad in itself or bad because they somehow impede or frustrate our attaining that which is really good for us.

One concrete example will suffice to illustrate this. In the opening sentence of the Metaphysics, Aristotle says that “all men by nature desire to know.” Knowledge is a real good, a good that is aimed at by an appetitive tendency inherent in human nature by reason of its cognitive capacity. All men need knowledge. Those who consciously seek knowledge desire aright; they want what they ought to seek. The man who, through sloth, turns away from seeking knowledge because he wishes to avoid the pain and effort of doing so, and who habitually chooses to indulge inordinately in the pleasures of sense rather than engage in thoughtful inquiry is not a virtuous man, for he has a habit of wrong rather than of right desire.

We can now apply our understanding of right desire to practical truth, conceived as being the conformity of a normative judgment with right desire. The judgment that I ought to seek knowledge is a normative truth because it conforms to right desire, desire that aims at a real good, a good that fulfills the natural appetite arising from my cognitive capacity. That true normative judgment is the conclusion of a practical syllogism in which the major premise is the one self-evident principle that lies at the foundation of all moral reasoning: “Real goods ought to be desired.”

The self-evidence of this proposition is exactly like the self-evidence of “the whole is greater than any of its parts.” Just as we cannot understand wholes without understanding them to be greater than any of their parts, so we cannot understand real goods without understanding them to be that which ought to be desired. Just as it is impossible to think of a whole that is less than any of its parts, so it is impossible to think of a real good that ought not to be desired, or of something that is really bad for us as something that ought to be desired.

The self-evident principle has the truth of an analytical proposition. Its truth cannot consist in conforming to right desire, for it is a truth about right desire itself. If to that self-evidently true normative principle, I add, as a minor premise, the true descriptive proposition that man has a natural desire for knowledge (which means that knowledge is a real good), I have constructed a practical syllogism that leads to the conclusion “I ought to seek knowledge.” This normative conclusion is not only true because it validly follows from premises that are true (one analytically true, the other factually true), but also because the judgment itself can now be seen to conform to right desire.

I said earlier that the modern conception of analytical truth is defective by virtue of limiting it to propositions that are trivial or uninstructive tautologies. While they are analytical in the sense that their truth is known from an understanding of their constituent terms, the proposition about wholes being greater than parts and the proposition about real goods being what ought to be desired are not trivial or uninstructive. These propositions are not verbal tautologies. The predicate is not contained in the meaning of the subject. The understanding of wholes involves the understanding of parts, and conversely; the understanding of real goods involves the understanding of what ought to be desired, and conversely.

One further point: Aristotle’s conception of practical or normative truth not only provides us with the ground for rejecting noncognitive ethics in all of its current varieties; it also enables us to dispose of the so-called “naturalistic fallacy” that, beginning with Hume, has occupied the attention of so many modern thinkers. Given the self-evident first principle that real goods ought to be desired, which is analytically true, and one or another true descriptive or factual proposition about man’s natural desires or needs, a normative conclusion validly follows and that conclusion is normatively true. Lacking a self-evident first principle as the ultimate foundation of all normative or practical reasoning, it would be impossible to reason validly to a normative conclusion. As Hume pointed out, from two factual or “is” premises, no normative or “ought” conclusion can be drawn.


As the consideration of practical or normative truth in Ethics, VI, 2, sent us back to Book III, Chs. 4-5 for the illuminating and related distinctions between real and apparent goods and between natural and acquired desires, so those distinctions send us back to Book I, Chs. 7-8 to re-examine the classification of goods there presented as well as the conception of happiness there set forth. There could scarcely be a more striking indication of the desirability of reading Aristotle backwards as well as forwards.

Though a large number of particular goods are mentioned in Book I — health, wealth, pleasures of sense, honor, and wisdom — and though these are classified as external goods, goods of the body, and goods of the soul and further differentiated as mere means or ends that are also means, Aristotle does not tell us whether all are real goods, whether only some are, or whether none is. I cannot find in Book I any reference, however slight, to the appetitive tendencies that are inherent in human nature, much less an inventory of man’s natural appetites that would enable us to ascertain the real goods at which they aim. However, from the fact that Aristotle thinks that a moderate supply of external goods (such consumable wealth as food and drink, clothing, and shelter) are necessary for a good life and from the fact that he also appears to think that such bodily goods as health, vigor, and a moderate amount of pleasure also contribute to living well, we are certainly entitled to infer that he regards the goods so far mentioned as real rather than apparent — goods men ought to try to possess if they aim at a life that befits their nature. His discussion of the functions peculiarly appropriate to man’s rational nature in Ch. 7 (1097b23-1098a15) also entitles us to infer that goods of the mind, such as knowledge and wisdom, are really good as fulfilling man’s cognitive faculty. To add to this list of real goods friendship and the advantages of living in a well-constituted state with the status of citizenship, we would have to appeal to Politics, Bk. I, Ch. 2, where we learn that man is by nature a political as well as a social animal and that the city comes into existence for the sake not of life, but of the good life. The indispensability of friendship for the good life is, of course, confirmed in Ethics, VIII.

For our present purposes, we need not pause to ask whether we now have exhaustively enumerated the real goods at which the appetitive tendencies inherent in human nature aim; nor need we be concerned here with which of these is a means to the attainment of others, which though a means to happiness is also desirable for its own sake, and which ought to be aimed at with or without some limitation on the quantity of it that ought to be sought. Proceeding on the assumption that an exhaustive enumeration of man’s natural appetites can be made, together with an exhaustive inventory of the real goods that man ought to seek, we must now ask about the relation of this set of real goods, correctly ordered, to happiness or the good life.

Ethics, I, 7 is indisputably clear on two points. One is that the good life as a whole is not a means to any further good, but rather the one and only ultimate or final end toward the attainment of which all other goods serve as means. The other point is that happiness has this status as a final end because the possession of it (only, of course, cumulatively in the course of a complete life) leaves nothing further to be desired. A happy or good life, Aristotle tells us, is one that is “lacking in nothing”; but though it is supremely good (i.e., “most desirable”), it must not be “counted as one good among others,” for “if it were so counted it would clearly be made more desirable by the addition of even the least of goods; for that which is added becomes an excess of goods, and of goods the greater is always more desirable” (1097b16-21).

Happiness, so conceived, cannot be the summum bonum if that is interpreted to mean “the highest particular good in a series of such goods” — the one among all partial real goods that is most desirable. Other goods might still be lacking. Instead, we must use the phrase totum bonum to express Aristotle’s conception of happiness — the whole of real goods, attained successfully and cumulatively in the course of a complete life. Each of the particular and partial real goods so far mentioned is a constitutive means to happiness, for they are the parts which, as acquired, serve to constitute the whole.

The one good that has not been mentioned so far is virtue (specifically, moral virtue). That it is indispensable to the attainment of happiness is also indisputably clear in Ethics, I, 7. But it is not a real good of the same sort as all the real goods so far mentioned. Even if it fulfills an inherent appetitive tendency as the other real goods do, it is not merely a constitutive means to happiness. It stands apart from all the rest by being the one operative means, functioning as that without which one cannot attain all the other real goods that one ought to seek as constitutive parts of a whole good life. We know, however, that it is only a necessary, not a sufficient, condition for their attainment, because Aristotle, in Book I, Chs. 8-10, makes indisputably clear that both good fortune and good habits of choice (moral virtue) are required for attainment of a good life. Moral virtue by itself makes a man, but not a life, good. A man must not only be virtuous but also be blessed by good fortune in order to achieve a good life for himself.

In Ethics, I, 4-5, Aristotle tells us that, though all men concur in their use of the word “happiness” to signify that which is desirable for its own sake and not as a means to anything else, they hold many different conceptions of what happiness or the good life consists in. That some of these are wrong conceptions, and that there is only one right conception of what happiness consists in, can only be explained in the light of the distinction between real and apparent goods, together with the self-evident first principle that all real goods ought to be desired.

If anyone thinks that happiness consists in a life of pleasure, or in a life devoted to the accumulation of wealth, or even one devoted to achieving honor, his mistake consists in ignoring the other real goods that he ought to seek in order to be happy. That being so, there is only one correct conception of happiness as the attainment of all the real goods that a man ought to seek in order to fulfill the appetitive tendencies inherent in human nature.

To say that happiness consists in achieving whatever goods a man happens to desire, according to the wants arising from his individual temperament and experience, or to say that one man is happier than another in proportion as he is more successful in satisfying his individual wants, whatever they may happen to be and without regard to the difference between right and wrong desires, would make Aristotle’s ethics purely utilitarian and pragmatic — teleological in the sense that it involves the consideration of the means to be chosen for the attainment of the end the individual happens to set himself. Only if there is one right end that all men ought to aim at, right because it consists in all the real goods that a man ought to seek as means to that end, does Aristotle’s ethics become deontological as well as teleological.

One marvelously succinct statement made by Augustine could have been made by Aristotle, for it combines the basic insights derived from Ethics, VI, 2 and Ethics, III, 4-5, with those derived from Ethics, I, 7. “Happy is the man,” Augustine said, “who has all that he desires, provided he desires nothing amiss.” Aristotle might have said the same thing as follows: “Happy is the man who has all that he desires, provided that he desires what he ought to desire and nothing that interferes with his attainment of the end that he ought to aim at.” Still another way of saying the same thing is by expanding the normative first principle as follows: “One ought to seek, in the course of a complete life, all the things that are really good according to the appetitive tendencies of one’s human nature, and nothing that interferes with the attainment of these goods in the right order and proportion.” Moral virtue as the firm habit of choosing aright is obviously indispensable to desiring nothing amiss. This brings us to Aristotle’s own succinct summary statement of his theory of happiness — that it consists in a complete life lived in accordance with complete virtue and attended by a moderate supply of external goods and whatever other goods may depend in part on good fortune (Ethics, I, 10, 1100b22-23, and especially 1101a14-21).

Originally published in Paideia, Special Aristotle Issue, MCMLXXVIII, George C. Simmons, ed., State University College at Buffalo and State University College at Brockport, 1978, pp. 158-166.

Your comments