ARISTOTLE SEEMS TO BE CORRECT when he asserts (1) that every association is to be accounted for by reference to some good which the members of that association hope to attain, precisely through their cooperation: or, in words close to Lincoln's, people form an association to accomplish together some good that each cannot attain, or cannot easily attain, through his own efforts. Even if this good--or, we might say, the "purpose" or "point"--of their association is not entirely clear to them, presumably there is some reason for their coordinated behavior, which can in principle be made evident. The coming together of persons in political society seems to be a form of association even more than most, because of its durability and coherence, and because of the authority of its rules. What, then, is the aim of political society--its common good? Is there a single correct answer here, or could political society correctly be arranged to attain any one of a variety of goals? What view of the common good is implicit in liberal democracies, and how does this differ from the more classical understanding as articulated in the political theory of Aristotle and perhaps also Aquinas?
John Finnis argues, in an extremely interesting and even provocative paper, (2) that the common good of political society does not itself instantiate a basic human good; that it is not, in particular, the object of a natural inclination, as to something intrinsically good; but that it is only a necessary means for the instantiation of such basic intrinsic goods, primarily within families. This view he expresses by calling the common good of political society "instrumental." (3) What is sought by members who associate in political society is something that assists and promotes family life; it is instrumental to other goods, goods which are sought for their own sake.
Finnis is not entirely clear about the details, but presumably his view is that the members of political society should work together to attain such things as: a military and police for protection against the aggressor, both external or internal; practices and infrastructure which serve to facilitate trade and commerce; and various means for advancing culture, such as schools, museums, and libraries. These together provide a framework within which families can flourish--a framework which Finnis refers to as "peace." Since laws should be restricted to the promotion of the common good, they are legitimately framed only if they advance peace or prohibit actions that would interfere with citizens' enjoyment of goods meant to be attained through civic peace. Laws are not competent, in particular, to direct citizens to any further end, such as the development of their own virtue in its own right, or the achievement of their own happiness. Presumably they are also incompetent to regulate life within households, except insofar as this has some real bearing upon justice and peace.
Let us say that an action or forbearance that is required for the establishment or preservation of peace is an act of "justice." Then laws, in the first instance, can command only acts of justice. Yet virtue is not something entirely unrelated to law. Laws may also promote virtue in citizens, Finnis allows, to the extent that such virtue is required if citizens are to succeed in doing acts of general justice. Finnis describes three respects in which this may be the case, which I here paraphrase:
(1) Laws may aim to promote citizens' habitually choosing just actions, since peace will obviously be more stable if it is chosen by citizens as a consequence of an established character: and so, for example, national holidays can presumably (4) be established by law, since such celebrations have the effect of encouraging civic spirit.
(2) Laws may promote virtues other than that of justice, to the extent that these are in some real sense needed by citizens in order for them to succeed in acting justly: for example, it may command (presumably) that a soldier not drink alcohol when on duty--an action characteristic of temperance but in the circumstances needed if the soldier is to fulfill his duty reliably. …