Natural Selection and the Capacity for Subjective Commitment

O nce you recognize them, commitments are everywhere. The commitment we all know is marriage. By giving up the option to leave for someone else, spouses gain security and an opportunity for a much deeper (and more efficient!) relationship than would otherwise be possible.Yet many commitments are not at all nice. When John F. Kennedy committed the United States to eliminating missiles from Cuba, millions of human lives were put at risk. When a thuggish-looking man offers unrequested fire insurance to a small retail shop, the implied threat of arson may well influence the owner's behavior. In a more banal vein, nearly everyone has waited for a repairman who never arrives. From the personal to the political to the mundane, commitments are everywhere. Threats and promises change people's beliefs and, therefore, their actions. In a world without commitments social exchanges arise mainly from helping relatives and trading favors. In such a world individuals can reliably be expected to act straightforwardly in their own interests. The advent of commitment changes everything. As soon as one individual finds a way to convince another that he or she will act other than in simple self-interest, social life is transformed. Now, individuals must consider the possibility that others may fulfill promises and threats. Sometimes the situation itself makes fulfillment worthwhile , but apparently irrational commitments also may influence others profoundly. A whole new category of social influence emerges. 2 Evolution and the Capacity for Commitment Reputations become important predictors of behavior, and people begin spending vast amounts of effort to convince others that they will fulfill their promises and threats. One way to convince others of one's credibility in a commitment is to give up options in order to change the incentives in a situation. Others observe that compliance is now in the person's interests, and change their expectations and behavior accordingly. By signing a lease, for instance, a person gives up the option to leave on short notice, and induces the landlord to give up the option of raising the rent in the middle of winter. Not all commitments, however, are backed by such tangible incentives. As Frank and Hirshleifer argue (Hirshleifer 1987; Frank 1988), people also can convince others that they will keep their promises by emotional displays that testify to their irrationality. Such commitments give rise to profound paradoxes. In order to influence others an individual must convince people that he …