Twice this fall, Dennis Prager has argued in National Review Online that religion is a necessary foundation for morality. I appreciate the effort he has put into challenging the antireligious polemic of writers such as Richard Dawkins. I agree with him that religion helps us to be good. On one important point, however, I believe that he is mistaken.

Because that point seems to be a view widespread among some Christians (though not, I think, one solidly grounded in traditional Christianity), I think that it is worth taking a closer look at Prager’s views.

Prager first makes his point abstractly:

If there is no God, the labels “good” and “evil” are merely opinions. They are substitutes for “I like it” and “I don’t like it.” They are not objective realities.

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He then gives a concrete example:

What would reason argue to a non-Jew asked by Jews to hide them when the penalty for hiding a Jew was death? It would argue not to hide those Jews.

Let’s begin with the abstract version. And let’s begin not with good character but with good health. On what basis do we judge high blood pressure, say, to be bad health? We don’t need to bring God into the picture. Human reason can tell us that high blood pressure is unhealthy. We don’t need to bring our own subjective preferences into the picture to see this. High blood pressure is bad health even for the suicidal.

In the same way that reason is sufficient to distinguish good from bad health, it is sufficient to distinguish good from bad character. Justice, generosity, honesty, temperance, and courage constitute good character. Just as proper blood pressure is necessary to living a full three-score years and ten, so the virtues I just named are necessary to living a full human life—a life lived in community with others and guided by reasoned judgments (not blown about by the winds of passion such as Paolo and Francesca in Dante’s Inferno).

Some people may not like the demands that rational judgments about health and character place on us. But the fact that Don Juan likes to commit adultery is no more relevant to whether the action is good than is someone’s fondness for chocolate relevant to whether chocolate is nutritious.

It is enough, in distinguishing good from bad actions, that we have a conception of what constitutes a genuinely human life. We get that in the same way we acquire our conception of human health—by our familiarity with human beings and with the human mode of being. Those are objective realities, however hard it might be for the anorectic (in the case of health) or the habitual liar (in the case of character) to recognize them.

Now for Prager’s example. Prager says that reason would tell the righteous Gentiles not to take the risk of hiding their Jewish neighbors during the years of Nazi occupation. I say that Victor Kugler and the others who hid Anne Frank were acting rationally; the person who informed on them, by contrast, was not. Rationality can do more than determine the best means of prolonging one’s life. It often requires one to risk one’s own well-being to protect others.

Prager seems to think, with David Hume, that “Reason is … the slave of the passions, and can never pretend to any other office than to serve and obey them.” Such an understanding of reason, however, misses the crucial difference between human rationality and animal “rationality.” Although I do not believe that animals have reason, it seems that those who insist that they do mean by “reason” only the ability to find effective means to achieving emotion-driven ends—to avoid what one fears and to obtain what one desires.

Human reason, however, can do more than identify effective means to satisfy selfish desires.

Specifically, it does two other things. First, human reason recognizes some ends (such as a life, whether long or short, that is characterized by generosity, courage, and the like) as worth pursuing. Better to be Socrates dissatisfied than a pig satisfied, to adapt slightly a famous dictum of John Stuart Mill, and on this Mill was right. Second, human reason makes it possible to recognize certain acts as generous or courageous (and therefore good) and others as miserly or cowardly (and therefore bad). All of this is grounded in our ordinary knowledge of human nature and human life. Knowing God exists is logically no more necessary to making sound moral judgments than it is to making sound medical judgments.

Of course, our emotions can knock us off our balance here. Out of fear or anger or hatred, we can fail to come to the aid of our neighbors; we can even join their persecutors. But it is emotion, not reason, that leads us to do so.

“Rationalizing” is, practically by definition, bad reasoning. That’s why “you’re rationalizing,” is an accusation. Good reasoning will sometimes demand that we lay down our lives for the good of others. Any rational being can see that a short and heroic life is better than a long life lived as a coward and a traitor. A perfectly rational being does not need to be ordered to risk his life in such a cause, and he does not await the promise of future reward or threat of punishment; a perfectly rational being, unlike the rest of us, would choose the risk because that choice would be a good one. Nathan Hale’s regret can be understood as readily by atheists as by anyone else.

Religion does have a role to play in our struggle to lead the moral life. It reinforces the moral principles that we can know by reason but might not have the time or skill to work out for ourselves. It gives us the grace so helpful in—perhaps even necessary for—overcoming the strong temptations to bad behavior that beset us. Finally, the promise of eternal reward or threat of eternal punishment gives us an extra incentive to act well when all else fails. We are not the perfectly rational character mentioned in the preceding paragraph. We need God and religion, not in order to recognize moral goodness, but for help in choosing it.

God does not, one might add, arbitrarily reward generosity and punish murder. He rewards generosity—He likes generosity—because it is good, because by developing that virtue we actualize more fully our human nature. Just as the zygote actualizes its human potential as it undergoes embryological development, so children and youth actualize their human potential as they undergo character development.

Goodness is objectively grounded in the nature of the being whose goodness is being evaluated. Good knives must be sharp enough to cut things; good human beings must be rational beings who recognize their own nature and know what they must be and do in order to actualize the potential that human nature provides.

God, in making us rational beings, gave us the ability to see the goodness of justice and generosity for ourselves, just as He has given us the ability to develop the science of physiology and the art of medicine. We don’t need to know that God exists to know good from bad. And we don’t need to refer to our or anyone else’s preferences; they are irrelevant. It is enough to know human nature—what kind of being we are and what kind of actions will bring us to fullness of human being.