Lowering the guard

Egoism, said Tocqueville, is “the rust of society.” Similarly, it is often said that trust is “the lubricant of society.” Everyday life would be impossibly difficult if we could not trust others to do what they say they will do, at least to some extent. Although scholars have defined trust in various ways, I shall use a simple behavioral definition: to trust someone is to lower one's guard, to refrain from taking precautions against an interaction partner, even when the other, because of opportunism or incompetence, could act in a way that might seem to justify precautions. By “opportunism” I mean shortsighted or “raw” self-interest, unconstrained by either ethical or prudential considerations. Typical opportunistic acts that may justify others’ taking precautions include telling a lie, cheating on an exam, shirking at the workplace, breaking a promise, embezzling money, being unfaithful to one's spouse, or choosing the non-cooperative strategy in a Prisoner's Dilemma.

One may or may not trust oneself to keep a bargain, stay away from alcohol, or keep the ship on a steady course when the Sirens are calling. Distrust of oneself is revealed by precommitment or by the construction of private rules (Chapter 15). These strategies can be costly, however, because of signaling effects. If others observe one instance of such precautionary behavior toward my future selves, they may infer, incorrectly as we saw in Chapter 12, that I lack self-control in general. Hence they may be reluctant to trust me on occasions when (1) my lack of self-control could be costly for them, (2) no precommitment devices are available, and (3) private rules are irrelevant, as they would be in a one-shot encounter. In many societies, there are norms against total abstention from alcohol as well as norms against drunkenness (Chapter 21).

Distrust can take one of two forms. On the one hand, one may simply abstain from interacting with a potential partner when the interaction would make one vulnerable to incompetence or opportunism. On the other hand, one may engage in the interaction but take precautions against these risks. Trust, therefore, is the result of two successive decisions: to engage in the interaction and to abstain from monitoring the interaction partner.