Because self-love is such a strong element in human nature, it is easy to understand why so many philosophers have regarded it as the sole basis on which all moral judgments have been made. That they have been mistaken in this can be shown by applying what Francis Bacon has termed a "crucial experiment." This can be done by examining instances in which an individual's private interest is separate from the public interest and even opposed to it.
Situations of this kind are not uncommon. A person engaged in business may learn that his chief competitor has been stricken with a fatal illness or has become the victim of some horrible accident. If he is a person who reacts in a normal manner, he will experience a genuine sense of sorrow for the man who has suffered the misfortune. His sorrow will not have been brought about because of any harm to his own private interests but will be due to the fact that as a human being, he is naturally sympathetic toward others. Again it is perfectly normal for a person to rejoice over the good fortune of others even though it may have been brought about at the expense of what one may have desired for himself.
Prolonged solitude does not bring enjoyment to an individual. To be happy, one must share his experiences with others. No normal person can be in a cheerful mood so long as those who are close to him are in a state of misery. Who is not pained by the tears and cries of a little child? Whenever one encounters the signs of sorrow and mourning, he is bound to feel a sense of compassion and of uneasiness. Wherever we go, and no matter what type of society we are associated with, it is still true that the joys and sorrows of other people excite within our own breasts feelings of pleasure or of uneasiness. This is not because of any selfish feelings we have toward ourselves but rather because of the tendency in our own nature to be sympathetic toward the feelings of other people.
This characteristic of human nature is illustrated again in the case of the theater, where the feelings and attitudes of the actors on the stage are communicated to the people who make up the audience. Let the actors express anger, resentment, sorrow, or rejoicing, and these feelings will be imitated, though to a lesser degree, by the people who observe them. Something like this is, according to Hume, the reason why the most entertaining form of poetry is the pastoral type, wherein the images of a gentle and tender tranquillity are communicated to people in terms of the common experiences of everyday life.
The reading of history furnishes another example of the way in which the feelings and sentiments of those who lived in former times are communicated to the ones who read about them. The noble actions of the past are applauded and the vices condemned as one does to some extent repeat within his own consciousness the deeds recorded in history. Anyone who is absolutely indifferent toward the deeds of the past will be equally indifferent toward the virtues and vices of the present.
In view of these considerations, it must be recognized that the social virtues are in every way due to their utility, and while self-interest is always involved to some extent, it requires something more than that to account for the way in which people normally behave toward one another. On this point, Hume says, "Thus, in whatever light we take this subject, the merit ascribed to the social virtues appears still uniform and arises chiefly from that regard which the natural sentiment of benevolence engages us to pay to the interests of mankind and society."
One of the main purposes of this discussion is to show that usefulness is not necessarily opposed to altruism. When the term is properly understood, it will be seen to include not only activities which are favorable to one's own interests but also those that promote the welfare of others even though these may at times be contrary to what one would normally desire for himself. The argument which is presented in this connection is especially important because of its bearing on Hume's entire theory concerning morals. It implies a conception of human nature that rules out the possibility of moral decisions being nothing more than an arbitrary statement of one's wishes or desires.
With reference to those who have insisted that pure selfishness is the sole basis for all morality, Hume points out that their doctrine rests on unproved and unwarranted assumptions. They have maintained that all actions are necessarily selfish because human nature is so constituted that no one can act contrary to his own interests. In support of this position, they have argued that the rules governing moral conduct have been put forth by politicians and other persons who have occupied positions of power. They have made the rules in harmony with their own selfish interests although they have, at the same time, pretended that they were made in the interests of their subjects. Anyone who wants to exploit others for his own gain will always find that it is much to his advantage to get people to believe he is acting in their behalf rather than for his own interests. It is even possible for a person to fool himself and thus to think that his actions are altruistic when as a matter of fact they are predominantly selfish.
Hume rejects the assumptions on which this theory of morality is based. He does, however, recognize the element of truth which it contains. Human nature is selfish to some extent, but the doctrine that it is entirely selfish is like other false theories based on only a part of the truth. Human nature is both selfish and altruistic, or at any rate it is possible for actions to be either of one kind or the other. Nothing less than this assumption will account for the way in which human beings express their approval or disapproval of different types of conduct.
That human nature has the capacity to act for something other than selfish ends is indicated in many different ways. Take, for example, the fact that any normal individual will approve acts of mercy and kindness which occurred in the distant past and which cannot possibly be regarded as having any particular advantage for himself. It is a very common thing for one to express praise and admiration for the noble and heroic deeds performed by persons who lived centuries ago. Expressions of this kind can mean nothing other than a natural tendency on the part of human beings to approve actions which have been directed toward the welfare of others and to do so regardless of any benefits to themselves which may have been derived from the deeds that were performed.
The case for altruism is even stronger when we recognize that it is a normal procedure for one to approve the good fortune which comes to others even though they may be directly opposed to what he desires for himself. We cannot help but admire the courage, bravery, and loyalty of our enemies in times of war, and this in spite of the fact that what they are doing is directly opposed to the cause that we serve. In a similar manner, we are happy for the success that has been achieved by our competitors in business, and we have feelings of sorrow and regret when some tragic misfortune falls upon them.
Sympathy for other people is an important characteristic of human nature, and it is for this reason that a person's approvals and disapprovals are determined not by selfish interests alone but also by that which pertains to the welfare of others. Moral sentiments do indeed have their source in utility, but it is a mistake to identify utility with selfishness alone.