If everyone could understand clearly the advantages which he would gain from conformity to the principles of justice and equity and would exercise the perseverance and self-discipline which is necessary to give up satisfactions of the moment for his long-range interests, there would be no need for government or what may be called a political society. It is because this type of understanding and self-control is not shared by all the members of society that we have laws and regulations along with the power of the state to enforce them. The sole reason why these laws must be obeyed is the fact that they constitute a useful method for preserving peace and order among the citizens of the state.
Among the nations of the world, there is a similar need for principles of conduct by which their dealings with one another may be regulated. Within certain limits, we may say that the same principles of justice and equity which prevail among individuals are also necessary for the well-being of the nations. It is generally understood that even among nations that are at war with one another, there are some rules that should always be obeyed. The safety of ambassadors must be maintained, the use of poisoned weapons must be forbidden, humane treatment must be accorded to prisoners of war, and certain precautions must be observed to prevent the destruction of civilian centers of population. All of these rules are recognized as useful means for protecting the interests of states in general.
There are, however, some important differences between kingdoms and individuals in their relations with one another. This accounts for the fact that many of the rules and regulations which have to do with the conduct of individuals within a given state are suspended in the area of international relations. In fact, the obligations of states to respect their commitments to one another are not regarded as binding to the same extent as they are among persons belonging to the same political unit. States may violate their treaties or alliances with one another whenever it appears essential to their own interests to do so.
This type of action would not, except in the most extreme cases, be considered right and proper among individuals. The reason for this is that human nature cannot subsist without the association of individuals, which is made possible only by obedience to the principles of justice and equity. On the other hand, states or kingdoms can subsist by themselves even though it may be inconvenient and in some instances extremely difficult for them to do so. The important point is that agreements are binding among both individuals and states in direct proportion to their usefulness in maintaining the security and well being of human societies.
Laws and customs pertaining to the behavior of the sexes can be seen to have their sole foundation in usefulness for promoting the peace and harmony of all who are concerned. Why, for examples, is chastity regarded as a virtue and adultery as a vice? The answer is that the comparatively long infancy of humanity requires the combination of parents and the security of a relatively stable home environment. Without these advantages, the child will not have the opportunity to grow and develop in a normal and healthy manner. Regulations pertaining to marriage and sexual relations are so useful in this connection that the desired conditions can scarcely be maintained without them. Apart from this usefulness, Hume tells us that the virtue of chastity would never have occurred to human beings.
In general, according to Hume, the virtue of chastity is regarded as more important for women than for men. The reason for this is directly related to childbearing. However, the regulations which were established for the purpose of safeguarding the interests of children continue to be recognized beyond the period for which they were originally intended. This accounts for the fact that adultery is forbidden after the period of childbearing is over as well as before. Laws forbidding incest, along with other regulations having to do with the conduct of the sexes, have also been enacted in order to aid still further the welfare of children and the security of the home.
Not all of the customs and conventions of society are incorporated into the laws of the land which makes it possible for them to be enforced by the police power of the state. Many of them are sustained merely by the force of public opinion. Nevertheless, violation of these customs may bring grave consequences to the offender, whose actions will be regarded as morally wrong. For example, tale-bearing and idle gossip concerning the private affairs of individuals are condemned in most societies and for very good reasons since they are a source of unhappiness and in many instances work great harm on the persons whose rights of privacy have been invaded.
All of these rules and regulations come into existence because of their usefulness in promoting the welfare of human society. Without them, it would be quite impossible for individuals to live in peace and in harmony with one another. Every society finds it necessary to have rules of some kind for the protection of its members. Even criminals have their own code of laws which forbid such practices as reporting on one another, disclosing secret information, failure to keep their agreements with one another, and anything else which they regard as detrimental to their own interests.
In this section, Hume illustrates his conception concerning the nature of justice by showing how it is set forth in the laws and customs that have been established in any well-regulated society. His discussion includes such items as laws pertaining to the tenure and use of private property, rules governing the conduct of international affairs, and customary behavior having to do with sex and marital relationships. In all of these instances, he is especially concerned to point out the dependence of these rules and regulations upon the changing needs of human beings as they adjust themselves to new and different environmental conditions. He argues that in an ideal society where there is an abundant supply of everything that is necessary for human welfare and where no one exploits other persons in order to gain some advantage for himself, there would be no need for justice; consequently, it would not exist.
Justice, according to Hume, has no existence apart from the laws and customs through which it is expressed. These do not come into existence until the need for them arises, and what will meet the needs of individuals under one set of conditions will not necessarily be adequate for this purpose under new and changed circumstances. From these considerations, it would appear that there is nothing constant or unchanging about the nature of justice. On the contrary, it would seem that the real meaning of the term is something that varies from time to time in accordance with the needs of people and the conditions under which they live.
The examples used in this section show beyond any reasonable doubt that the application of the principles of justice to concrete cases will always be dependent on the particular circumstances that are involved. For instance, what is considered to be just and right in matters pertaining to private property is determined by a number of different factors. Whether the property has been inherited, acquired by fraudulent means, needed for the satisfaction of debts, used in a manner that is detrimental to the interests of others, or subject to many other considerations are all matters which must be taken into account. Laws concerning property have been made solely for the purpose of meeting the needs of people, but because of changing conditions, this purpose has never been completely realized. In order to make progress toward that goal, it has been necessary to change the laws from time to time.
In regard to sex morality, it is observed that a wide variety of customs and laws are recognized by different societies. Some of the rules and regulations are included in the laws of the land, but others are enforced only by the power of public opinion. The important point, so far as Hume's argument is concerned, is the fact that whatever the regulations concerning sex behavior may be, the only basis for their existence is that they have been regarded as necessary for the welfare of the society as a whole. It is true that some of the rules remain in force long after their immediate usefulness for a particular class of persons has been accomplished. It is also true that the moral standards which have been established are not always the same for both sexes.
Nevertheless, it can be said that all of the laws and customs having to do with sex relationships had their origin in an attempt to meet the needs of the people as a whole. Furthermore, the changes that have taken place in these regulations from time to time have been directed toward the same end. There is no single rule concerning sex behavior that can be regarded as adequate under any and all conditions. Under certain circumstances, monogamy is the form which is best suited for human welfare, but under other conditions a different type of behavior may have more beneficial results.
In the field of international relationships, there are certain rules of conduct which are essential in order to safeguard the security and the welfare of the nations that are involved. Although these rules had their origin in an attempt to meet the needs of human beings, they are not usually regarded in quite the same way as the laws which operate within the boundaries of the particular state to which one belongs. Nations do not hesitate to violate the terms of their agreements when it is to their own interest to do so. The reason for this is that the nations are not nearly so dependent on one another as is true of the people who belong to a single state.
At the time when Hume lived, each nation was self-sufficient to a much greater degree than is true of the present day. Scientific developments have made the nations of the world more interdependent than at any previous period in human history. The new conditions have necessarily been accompanied by new and changing conceptions of international justice.
Throughout his discussion of this topic, Hume has emphasized the fact that human conceptions of justice change from time to time. What one person or group of persons may regard as just will not necessarily coincide with the opinions held by other members of the same society. Any attempt to apply the principles of justice to concrete situations will vary with the different circumstances that arise. In this respect, the argument which he has presented is quite convincing. However, these facts do not warrant the conclusion that there is nothing constant or unchanging about the nature of justice.
If decisions concerning the meaning of justice were entirely arbitrary, the term could mean anything, which would be equivalent to no meaning at all. Apparently Hume would not grant that this is the case, although there are passages in his treatment of the subject that would indicate this position or at least one that is closely related to it.