Suppose you’re wandering through a desert wasteland, outside of the borders of any political community, and you come across another person. Why should you care about their well-being rather than attack them or forcibly take their possessions for yourself? The aim of this post is to briefly outline an Aristotelian approach to this question.
As Aristotle explains in the first book of the Nicomachean Ethics (NE), everything we do is done ultimately in pursuit of happiness. At the outset, “happiness” is simply the label for something we don’t yet understand, but which we know enough to reason about. Pretty quickly, Aristotle establishes that (1) it is the chief or final good, something desirable for its own sake and never for the sake of something else; (2) it is self-sufficient, such that when isolated it makes life worth living and lacking in nothing; and (3) via the function argument that it is about living life in accordance with complete virtue, rather than in simply having something or being in some passive state. For the most part, Aristotle spends NE exploring the different aspects of these ideas, like how we develop the virtues, what virtues there are, the role and nature of friendship, how virtue relates to pleasure, and so on. Throughout all of this, it is clear that Aristotle sees human life as something lived in community with others, but as far as I’m aware there is no explicit discussion about this until the closing section of the book, which serves as a transition to the Politics. Then, early in the first book of the Politics, he makes the following point:
We thus see that the city exists by nature and that it is prior to the individual. For if the individual is not self-sufficient when he is isolated he will stand in the same relation to the whole as other parts do to their wholes. (Politics I.2)
His reasoning here presupposes the foundation laid in the NE. We said that humans by nature pursue happiness, and that whatever happiness is it is self-sufficient and an activity of life. So, if individual humans are not self-sufficient, then whatever happiness is it cannot be limited to an individual life alone—that is, it cannot be something which individuals have in isolation from one another. Rather, it must be that happiness is a common good rather than a private good.
Generally speaking, a common good is a good of a community. But when we say that happiness is a common good rather than a private good we have something more specific in mind. To see this, we need to distinguish between different kinds of common goods. First, there is what we could call a cumulative good, which is a sum of goods belonging to the members within the community. This is opposed to a singular good, which is the good of just one member of the community. My wealth is my singular good, but the wealth of the entire country is a cumulative good made up of the wealth of all the individuals therein. Second, there is what we could call a communal good, which is a good that belongs to the community rather than to the members of that community. This is opposed to an individual good. With communal goods, the community is a sort of quasi-individual, so that a good either belongs to the community or to one of the individuals, but not both. Public parks or government buildings are communal goods, whereas private property is an individual good. When we say that happiness is a common good, we have neither the cumulative nor the communal senses in mind. Rather, what we mean is that happiness is a communicable good, something which is shared by the members of a community without thereby being diminished. This is opposed to a private good, which is something which either cannot be shared or something that is diminished when shared. A public radio broadcast, justice, and victory in a sports match are communicable goods, whereas particular food or my own health are private goods. So, when we say that happiness is a common good, we do not deny that it is an individual good. Rather, it is something enjoyed by each of the individuals in the community without having to be carved up and apportioned to those members.
Happiness must be a common good because it must be self-sufficient, and individual humans lack self-sufficiency in all sorts of ways. Let’s briefly summarize the areas in which we lack self-sufficiency. First, we depend on others for both the acquisition and maintenance of the resources we need to live a happy life, including external goods, bodily goods, and goods of the soul such as the virtues. Second, we depend on others in the proper exercise of the virtues: the complexities of life and our own limitations all make it difficult to figure out how best to act in any given situation (prudence), and even when we know what to do it is difficult to distance ourselves from our passions, in order to critically evaluate them so that we might regulate our desires (temperance) and our responses to obstacles (fortitude). Such reasoning and distancing, which is required for living in accordance with the virtues, can only be done reliably in cooperation with others. Third, MacIntyre suggests that our own conception of self depends on others knowing us, and is necessary if we are to imagine possible futures for ourselves that guide our daily choices toward virtuous lives. And fourth, we are vulnerable to various impairments throughout our lives, which hinder our ability to live in accordance with complete virtue. We start out impaired as children, totally dependent upon those around us to develop us into responsible practical reasoners. As adults we remain vulnerable to illness, injury, disability, old age, extortion and manipulation by others, and unfortunate or unexpected outcomes.
Once we understand the ways in which individual humans lack self-sufficiency, we can draw conclusions about what a community must be like in order for its common good to constitute happiness. For one, the common life of this community must be governed by a principle we can call “distributive reciprocity.” By reciprocity we mean that the community forms a network of givers and receivers, from which we benefit as receivers and to which we contribute by giving of ourselves for the sake of others. It is by virtue of such a network that the community as a whole can move beyond the limitations of its individual members. This reciprocity is distributive rather than commutative, because it is not based on repaying this or that person for something we have received from them, but rather based on what benefits others and our ability to help them, especially in times of need. Often those to whom we give will be other than those from whom we have received, and rarely will we be required to give exactly what we received, or even something commensurable with it. The point of distributive reciprocity is not to “balance my books” with those around me (as it would be in commutative reciprocity), but to participate in a community of unconditional giving and humble receiving, so that we may together overcome our individual lack of self-sufficiency.
Commutative reciprocity certainly has a place in such a community (it will be important for any trading context, for instance) but it cannot be the sort of reciprocity that governs the community at a fundamental level, for two reasons. First, in a community governed by commutative reciprocity each member must give or receive for the sake of their own private good, which we’ve seen is not self-sufficient enough to constitute happiness. Second, in a community governed by commutative reciprocity, receiving from someone is conditioned on the ability to give to them, which does not produce the sort of stability necessary for happiness. We start out impaired as children, reliant on our parents and teachers to train us up to be independent adults. This benefit is received without us first paying our parents something, and indeed many of us will never be able to pay our parents back for the goods they have secured for us. Beyond this, there is no guarantee about when we will succumb to our vulnerabilities, and so no guarantee that we would be able to give to those people enough to justify us receiving their help. Thus, we are left just as vulnerable as we were as an individual—if not more, because of the possibility of people taking advantage of us when we’re in need.
So, then, happiness is the common (communicable) good of a community achieved in a shared life governed by a principle of distributive reciprocity. This is why Aristotle concludes from our lack of self-sufficiency that the individual is naturally like a part to a whole. This whole goes by various names: Aristotle calls it the city or state, we could call it the political community, or we might call it the complete community in contrast to the many incomplete communities to which we belong. The completeness of a community refers to the range of the human good that the community encompasses. In the complete community the members participate as humans and the common good of the community is therefore human happiness itself, which is the complete human good. But in incomplete communities the members participate in more limited capacities—as a father, as a worker, as a team player, as a student, etc.—and so the common goods of these communities do not extend to the full scope of the human good for its members, but only to scopes that correspond to these limited capacities. The complete community comes into existence when the various overlapping incomplete communities are organized in order to achieve happiness, since otherwise there would be some human goods outside of the purview of the complete community, which would undermine its completeness.
Returning to the question that we posed at the beginning: why should you care about the well-being of the person you encounter in the desert wasteland rather than attack them or forcibly take their possessions? All other things being equal, it’s because as humans you are both ordered towards happiness and happiness is a common good of the shared life of a complete community. Thus, you should work together as the start of such a community. On the other hand, if they start attacking you or show themselves to be untrustworthy, then the wise thing to do would be to avoid them or defend yourself rather than pursuing such a community with them. Or maybe they are trustworthy but not generally virtuous, in which case you can work with them on a utility basis while at the same time trying to reduce their negative influence on you—after all, even in the complete community there are relationships governed only by utility. Of course, there is more to consider, but we can start to see how the Aristotelian framework helps us to evaluate the factors at play, explaining both why seeking the well-being of others is worthwhile but at the same time helping us reason about when it is inappropriate.
 I have been thinking about this sort of question on and off over the last few years, but until recently have struggled to make any progress in answering it. It started when I wrote a post on the good of others, and then later came across James Chastek’s post on two reasons for forming political associations. After reading Chastek, I realized I had missed something important in my original post, but I wasn’t entirely clear on what it was. Over the years I have explored various parts of the underlying Aristotelian theory, but was unable to come to any satisfactory conclusions. That is, until at the suggestion of others I began reading Alasdair MacIntyre’s work, particularly his book Dependent Rational Animals, which I would highly recommend to anyone interested in these sorts of questions.
 For more on common goods, see Charles De Koninck’s “On the Primacy of the Common Good” and Jeffery Nicholas’s “The Common Good, Rights, and Catholic Social Thought.”
 We mention only the cardinal virtues here since these cover all the other virtues. We have left out justice (the fourth cardinal virtue) because it presupposes that we are ordered toward living in community with others, which is what we’re trying to establish. See David Oderberg, “On the Cardinality of the Cardinal Virtues” and Aquinas’s ST II-I, Q 61, A 2 and II-II, QQ 47–170.
 Alasdair MacIntyre, Dependent Rational Animals, p. 94–6. The gist of his argument is that any person’s awareness of their own identity is direct and ungrounded by deeper criteria which could be used to form a concept of self, while other people’s awareness of that person’s identity are necessarily criteria-grounded. A person’s own concept of self arises, then, by their recognition of the coincidence of these two ascriptions, allowing them to adopt a generally reliable conception of self through knowledge of them by others.
 See MacIntyre, Dependent Rational Animals, pp. 63–128 for a lengthy discussion of all of this.
 This is the name I have given to the version of reciprocity discussed but left unnamed by MacIntyre in Dependent Rational Animals, pp. 99–101. He later introduces the name “just generosity” to describe the virtue that is necessary to achieve this sort of reciprocity within a community (pp. 126–8).