“In 1979, [Robert] Axelrod decided to use computers to seek the best strategy for when to extend and when to withhold one's trust. He invited experts to submit programs that were, in essence, a set of rules stating when a player would cooperate and when it would defect in a series of interactions similar to the culminating event in the TV game show.

Fourteen people agreed to participate in the tournament. They came from the disciplines of psychology, economics, political science, mathematics, and sociology. "Most of the entrants were recruited from those who had published articles on game theory," wrote the professor. No one could claim they were "not strategically sophisticated enough" to understand the power of being distrustful. They submitted a diverse group of strategies. Just like the variety of potential partners you encounter in any setting, the programs included jerks, saints, and many permutations in between.

The winner of the tournament turned out to be the simplest of all the programs. It was submitted by Russian-born psychologist Anatol Rapoport. Called "Tit for Tat," it began by cooperating on the first move, and then it just mimicked what its counterpart did on the previous move. In its simplicity, Tit for Tat was an elegant solution to the trust problem. It had several features of a good human partner that made it most successful in the tournament.

It got things off on the right foot by displaying trust on the beginning move, and unless it was betrayed, it never proved untrustworthy. In these ways, Tit for Tat and the others that performed best in the contest were not what Hobbes or Nash or von Neumann would have predicted.

"Surprisingly, there is a single property which distinguishes the relatively high-scoring entries from the relatively low-scoring entries. This is the property of being nice, which is to say never being the first to defect," wrote Axelrod. When two trusting strategies met each other, they formed an elementary partnership, cooperating through almost the entire game, raising each other's scores along the way.

While it was friendly, Tit for Tat was no fool. As soon as it was betrayed, it retaliated on the next move and would continue refusing to cooperate until the other player ceased the hostilities. Because of this reflex, the strategy was "not very exploitable," wrote Axelrod. Such a fallback is crucial to the survival of otherwise obliging individuals. Without retaliation to keep them in check, just a few egotists or attackers can quickly overrun a benevolent population. Appealing to a sense of fair play works with most people, but a pernicious minority will exploit their colleagues' trust if nothing stands in their way.

Another winning feature of Tit for Tat was that as fast as it went to battle stations, it just as quickly returned to trusting when its counterpart did so. It was forgiving. "Of all the nice rules, the one that scored lowest was also the one that was least forgiving," Axelrod found.

The professor decided to try the experiment again, distributing the results of the first tournament to drum up additional interest. He wanted to know if more players and a wider variety of strategies could improve the results. Axelrod invited the initial set of players to try again. He also took out ads in computer journals. The response was more than he anticipated. Sixty-two entries came in from the United States, Canada, Great Britain, Norway, Switzerland, and New Zealand. They came from professors of computer science, physics, economics, psychology, mathematics, sociology, political science, and evolutionary biology. One came from a 10-year-old kid.

There were more than a million moves in the second tournament. All those who entered a strategy knew Tit for Tat won the first tournament, and why. Yet when all the strategies had a chance to interact with each other, the winner was once again Rapoport's simple rule, which he resubmitted unaltered from the first tournament. "So Tit for Tat, which got along with almost everyone, won the second round of the tournament just as it had won the first round," wrote Axelrod. It is "clearly a very successful strategy," he concluded.

The lesson in Axelrod's tournament lies in how forcefully it contradicts the supposedly savvy strategy of being selfish. Hobbes was wrong. Nash was wrong. Von Neumann, thankfully, was wrong. People are not purely selfish and calculating; they are reciprocating, both positively and negatively. They reflect what they receive. Reciprocity is one of the most powerful forces in human nature.

In many ways, Axelrod's tournament confirmed the wisdom of a passage in the Edda, a 13^th-century collection of Norse epic poems. "A man ought to be a friend to his friend and repay gift with gift," it states. "People should meet smiles with smiles and lies with treachery." The positive side of these deep-rooted emotions is the glue that holds together a partnership.

The most important element in forming and maintaining a variety of strong partnerships is not your craftiness, but your willingness to take the risk of trusting numerous potential partners and your diligence in repaying the trust they place in you. If you're not careful, you could be so "strategically sophisticated" that no one wants to work with you or that you fail to recognize or reciprocate collaborative overtures from people all around you. Just like Tit for Tat, you need to be eager to cooperate; to make early, friendly overtures to your partner; to stubbornly refuse to make the first hostile or neglectful move; and to be quite willing to forgive.

The ultimate twist to the research on trust is what it reveals about your collaborative environment. If you are like most people, you assume you are simply making reasonable reactions to the people with whom you interact. You believe you are working with the hand you were dealt. To the degree you compete, you probably feel as though you are just reacting to the competition around you. You probably attribute your lack of partnerships to a lack of good partners.

But in a Tit for Tat world, where most people return good for good and bad for bad, the world you inhabit is the world you make. Your reputation precedes you, biasing the way new colleagues deal with you. Your first moves, friendly or hostile, tip the balance for future interactions. When you exhibit trust, you will most often find trustworthiness. When you are selfish, you will most often find selfishness. When you compete, others must resort to competition. If you choose to play the game strictly for your own advantage, your attempts at collaboration will indeed be "solitary, poor, nasty, brutish, and short."

In the end, the degree to which you succeed in forming trusting partnerships is less a reflection of how much people trust you than how much you trust them -- less a reflection of their trustworthiness than of your own.”