On Moral Philosophy

Mortimer J. Adlerby Mortimer J. Adler, Ph.D.


Philosophy, seeking to establish itself as knowledge rather than mere speculation and unfounded opinion, is afflicted with a series of errors that have occurred in modern times. These must be corrected in order for philosophy to succeed in its effort to provide us with ethical and political knowledge.

In my opinion, Aristotle’s Nicomachean Ethics, properly construed, is the only sound, pragmatic, and undogmatic work in moral philosophy that has come down to us in the last twenty-five centuries (it is the ethics of common sense and is both teleological and deontological). Its basic truths are as true today as they were in the fourth century B.C. when that book was delivered as a series of lectures in Aristotle’s Lyceum.

Of course, it contains some errors. All books do. Of course, not everything it says or every distinction it makes is of equal importance. But when it is carefully read with an eye to its main theses, we are as enlightened by it today as were those who listened to Aristotle’s lectures when they were first delivered.

The reason this can be so is that the ethical problems that human beings confront in their lives have not changed one bit over the centuries. Moral virtue and the blessings of good fortune are today, as they have always been in the past, the keys to living well, unaffected by all the technological changes in the environment, as well as those in our social, political, and economic institutions. The moral problems to be solved by the individual are the same in every century, though they appear to us in different guises.

Here, instead of trying to expound Aristotle’s Ethics in summary fashion, I am going to state the indispensable conditions that must be met in the effort to develop a sound moral philosophy that corrects all the errors made in modern times.

First and foremost is the definition of prescriptive truth, which sharply distinguishes it from the definition of descriptive truth. Descriptive truth consists in the agreement or conformity of the mind with reality. When we think that that which is, is, and that which is not, is not, we think truly. To be true, what we think must conform to the way things are. In sharp contrast, prescriptive truth consists in the conformity of our appetites with right desire. The practical or prescriptive judgments we make are true if they conform to right desire; or, in other words, if they prescribe what we ought to desire.

It is clear that prescriptive truth cannot be the same as descriptive truth; and if the only truth that human beings can know is descriptive truth–the truth of propositions concerning what is and is not–then there can be no truth in ethics. Propositions containing the word “ought” cannot conform to reality. As a result, we have the twentieth-century mistake of dismissing all ethical or value judgments as noncognitive. These must be regarded only as wishes or demands we make on others. They are personal opinions and subjective prejudices, not objective knowledge. In short, the very phrase “noncognitive ethics” declares that ethics is not a body of knowledge.

Second, in order to avoid the naturalistic fallacy, we must formulate at least one self-evident prescriptive truth, so that, with it as a premise, we can reason to the truth of other prescriptives. Hume correctly said that if we had perfect or complete descriptive knowledge of reality, we could not, by reasoning, derive a single valid ought. Modern efforts to get around this barrier have not succeeded, first because modern writers have not had a definition of prescriptive truth, and second because they have not discovered a self-evident prescriptive truth.

Immanuel Kant’s categorical imperative, which he regarded as self-evident, is as empty as the Golden Rule. I will present the formulation of a self-evident prescription that replaces Kant’s categorical imperative, but I cannot do this until I have explained the third condition to be satisfied. Kant’s categorical imperative is purely formalistic. The categorical imperative to be stated presently is substantive since it is based on human nature and its right desires.

Third, the distinction between real and apparent goods must be understood, as well as the fact that only real goods are the objects of right desire.

In the realm of appetite or desire, some desires are natural and some are acquired. Those that are natural are the same for all human beings as individual members of the human species. They are as much a part of our natural endowment as our sensitive faculties and our skeletal structure. Other desires we acquire in the course of experience, under the influence of our upbringing or nurturing, or of environmental factors that differ from individual to individual. Individuals differ in their acquired desires, as they do not in their natural desires.

We have two English words for these two kinds of desire, words that help us to understand the significance of their difference: “needs” and “wants.” What is really good for us is not really good because we desire it, but the very opposite. We desire it because it is really good. By contrast, that which only appears good to us (and may or may not be really good for us) appears good to us simply because we want it at the moment. Its appearing good is the result of our wanting it, and as our wants change, as they do from day to day, so do the things that appear good to us.

Now, in light of the definition of prescriptive truth as conformity with right desire, we can see that prescriptions are true only when they enjoin us to want what we need, since every need is for something that is really good for us.

If right desire is desiring what we ought to desire, and if we ought to desire only that which is really good for us and nothing else, then we have found the one controlling self evident principle of all ethical reasoning–the one indispensable categorical imperative. That self-evident principle can be stated as follows: we ought to desire everything that is really good for us.

Readers may ask why this is self-evident; the answer is that something is self-evident if its opposite is unthinkable. It is unthinkable that we ought to desire anything that is really bad for us; and it is equally unthinkable that we ought not to desire everything that is really good for us. The meanings of the crucial words “ought” and “really good” co-implicate each other, as do the words “part” and “whole” when we say that the whole is greater than any of its parts is a self-evident truth.

Given this self-evident prescriptive principle, and given the facts of human nature that tell us what we naturally need, we can reason our way to a whole series of prescriptive truths, all categorical. Kant was wrong in thinking that practical reason itself can formulate a meaningful categorical imperative, without any consideration of the facts of human nature. It is human nature, not human reason, that provides us with the foundations of a sound ethics.

Fourth, in all practical matters or matters of conduct, the end precedes the means in our thinking about them, while in action we move from means to ends. But we cannot think about our ends until, among them, we have discovered our final or ultimate end–the end that leaves nothing else to be rightly desired. The only word that names such a final or ultimate end is “happiness.” No one can ever say why he or she wants happiness because happiness is not an end that is also a means to something beyond itself.

This truth cannot be understood without comprehending the distinction between terminal and normative ends. A terminal end, as in travel, is one that a person can reach at some moment and come to rest in. Terminal ends, such as psychological contentment, can be reached and then rested in on some days, but not others. Happiness, not conceived as psychologically experienced contentment, but rather as a whole life well lived, is not a terminal end because it is never attained at any time in the course of one’s whole life. If all ends were terminal ends, there could not be any one of them that is the final or ultimate end in the course of living from moment to moment. Only a normative end can be final and ultimate.

Happiness functions as the end that ought to control all the right choices we make in the course of living. Though we never have happiness ethically understood at any moment of our lives, we are always on the way to happiness if we freely make the choices that we ought to make in order to achieve our ultimate normative end of having lived well. But we suffer many accidents in the course of our lives, things beyond our control–outrageous misfortunes or the blessings of good fortunes. Moral virtue alone–or the habits of choosing as we ought–is a necessary, but not sufficient condition of living well. The other necessary, but also not sufficient condition is good fortune.

The fifth condition is that there is not a plurality of moral virtues (which are named in so many ethical treatises), but only one integral moral virtue. There may be a plurality of aspects to moral virtue, but moral virtue is like a cube with many faces.

The unity of moral virtue is understood when it is realized that the many faces it has may be analytically but not existentially distinct. In other words, considering the four so called cardinal virtues–temperance, courage, justice, and prudence–the unity of virtue declares that no one can have any one of these four without also having the other three.

Since justice names an aspect of virtue that is other regarding, while temperance and courage name aspects of virtue that are self-regarding, and both the self- and other regarding aspects of virtue involve prudence in the making of moral choices, no one can be selfish in his right desires with out also being altruistic, and conversely.

This explains why a morally virtuous person ought to be just even though his or her being just may appear only to serve the good of others. According to the unity of virtue, the individual cannot have the self-regarding aspects of virtue– temperance and courage–without also having the other regarding aspect of virtue, which is justice.

The sixth and final condition is acknowledging the primacy of the good and deriving the right therefrom. Those who assert the primacy of the right make the mistake of thinking that they can know what is right, what is morally obligatory in our treatment of others, without first knowing what is really good for ourselves in the course of trying to live a morally good life. Only when we know what is really good for ourselves can we know what are our duties or moral obligations toward others.

The primacy of the good with respect to the right corrects the mistake of thinking that we are acting morally if we do nothing that injures others. Our first moral obligation is to ourselves–to seek all the things that are really good for us, the things all of us need, and only those apparent goods that are innocuous rather than noxious.


The Moral Liberal recommends Mortimer J. Adler’s, The Great Ideas: A Lexicon of Western Thought


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Mortimer Jerome Adler (1902 – 2001) was an American philosopher, educator, and popular author. As a philosopher he worked within the Aristotelian and Thomistic traditions. He worked for Columbia University, the University of Chicago, Encyclopædia Britannica, and Adler’s own Institute for Philosophical Research. Adler went on to found the Great Books of the Western World program and the Great Books Foundation. He founded and served as director of the Institute for Philosophical Research. He also served on the Board of Editors of Encyclopædia Britannica from its inception and became its chairmen. Spearheading the fifteenth edition of Britannica he was instrumental in the major reorganization of knowledge embodied in that edition. He founded the Paideia Program, a grade-school curriculum centered around guided reading and discussion of difficult works (as judged for each grade). With Max Weismann, he founded the Center for the Study of The Great Ideas. He also served along with Max Weisman on the Board of Directors of Jonathan Dolhenty’s Radical Academy.