Hobbes emphasized that the state of nature is a state of war because it fundamentally involves distrust. Exiting the state of nature and the conflicts it inevitably fosters is therefore a matter of establishing trust. Extant discussions of trust in the philosophical literature, however, focus either on isolated dyads of trusting individuals or trust in large, faceless institutions. In this paper, I fill the gap between these extremes by analyzing what I call the logic of communities of trust. Such communities are best understood in terms of interlocking dyadic relationships, in which trust figures as an equivalence relation. In such a community, trust is symmetric, transitive, and reflexive. To the extent that I trust you to do your part with respect to our shared field of trust, you also trust me to do my part with respect to our shared field of trust. To the extent that I belong to a community of trust, I trust myself to do my part with respect to our shared field of trust. To the extent that I trust you to do your part with respect to our shared field of trust, I place delagatory trust in anyone you in turn trust to do their part with respect to our shared field of trust.

Few communities of trust live up to this demanding ideal, and those that do tend to be small (between five and fifteen individuals – perhaps as many as thirty-five, as has been illustrated by research by Robin Dunbar and his colleagues). Nevertheless, such communities of trust serve as the conditions for the possibility of various important epistemic, prudential, and moral goods. They are arguably our best bet for achieving mutual or even common knowledge. They make possible ongoing cooperative endeavors that are not backed by coercive state force. They define circles of friendship. Jonathan Shay, in Achilles in Vietnam (1995), goes so far as to argue that “healing from trauma depends on communalization of the trauma – being able safely to tell the story to someone who is listening and who can be trusted to retell it truthfully to others in the community.” This is because what Shay later calls “social trust” (Odysseus in America 2003, pp. 175-6) “requires at least three people. Dyadic trust between two people, no matter how many times it is pair-wise created, does not make a community. A community begins with the addition of the third person, and with the belief of each individual that when alone together the other two will continue to safeguard the interests of each even when that person is absent.”

If this is right, then communities of trust provide us with great epistemic and moral goods. However, communities of trust also make possible various problematic phenomena. They tend towards nepotism and cronyism. They can become insular and walled-off from the surrounding community, leading to distrust of the out-group. Their members have an increased vulnerability to betrayal and disappointment. And they can lead their members to abandon public goods for tribal or parochial goods. These drawbacks of communities of trust arise from the very same mechanisms that give them positive epistemic, prudential, and moral value – and so can at most be mitigated, not eliminated.