The Calculus of Selfishness

The Calculus of Selfishness

The Calculus of Selfishness

The Calculus of Selfishness


How does cooperation emerge among selfish individuals? When do people share resources, punish those they consider unfair, and engage in joint enterprises? These questions fascinate philosophers, biologists, and economists alike, for the "invisible hand" that should turn selfish efforts into public benefit is not always at work. The Calculus of Selfishness looks at social dilemmas where cooperative motivations are subverted and self-interest becomes self-defeating. Karl Sigmund, a pioneer in evolutionary game theory, uses simple and well-known game theory models to examine the foundations of collective action and the effects of reciprocity and reputation.

Focusing on some of the best-known social and economic experiments, including games such as the Prisoner's Dilemma, Trust, Ultimatum, Snowdrift, and Public Good, Sigmund explores the conditions leading to cooperative strategies. His approach is based on evolutionary game dynamics, applied to deterministic and probabilistic models of economic interactions.

Exploring basic strategic interactions among individuals guided by self-interest and caught in social traps, The Calculus of Selfishness analyzes to what extent one key facet of human nature--selfishness--can lead to cooperation.


You need not be a scheming egotist to pick up The Calculus of Selfishnes. It is enough to be interested in the logic behind the ceaseless give-and-take pervading our social lives. The readership I had in mind, when writing this book, consists mostly of undergraduates in economics, psychology, or evolutionary biology. But simple models of social dilemmas are of general interest.

As the word Calculus in the title gives away, you will need a modicum of elementary mathematics. Beyond this, all the game-theory expertise you need is painlessly provided step by step. As to the Selfishnes in the title, I do not mean blind greed, of course, but “enlightened self-interest,” by which, according to Tocqueville, “Americans are fond of explaining almost all the actions of their lives; … They show with complacency how an enlightened regard for themselves constantly prompts them to assist each other.” Such complacency may well be justified; but theoreticians cannot share it. Most of them feel that it is hard to understand why self-interested agents cooperate for their common good.

In the New Year 2000 edition of Science, the editors listed “The evolution of cooperation” as one of the ten most challenging problems of the century. My book certainly does not claim to solve the problem. Having worked for twenty years in the field, I know that it progresses far too fast to allow an encyclopedic presentation, even when restricted to cooperation in human societies, which is a tiny fraction of all the cooperation encountered in biology.

Rather than trying to address all aspects, this book concentrates on one issue only, the reciprocity between self-interested individuals, and explores it for a small number of elementary types of interactions. The method is based on an evolutionary approach: more successful strategies become more frequent in the population. We neglect family ties, or neighborhood relations, or individual differences, or cultural aspects. It is best to state this self-limitation right at the beginning. I hope not to convey the impression that family ties, neighborhood relations, or individual aspects, etc., play no role in the evolution of cooperation and that it all reduces to self-interest; just as theoretical physicists writing a treatise on gravity do not imply, thereby, that other forces in the universe can be ignored. This being said, the current trend in economic life seems to lead away from nepotism, parochialism, and face-to-face encounters, and toward interactions between strangers in a well-mixed world.

The introduction (an entire chapter without any formulas) describes some of the most basic social dilemmas. Thinkers throughout the ages have been fascinated by the topic of self-regarding vs. other-regarding behavior, but the use of formal models and experimental games is relatively recent. Ever since Robert Trivers introduced an evolutionary approach to reciprocity, the Prisoner's Dilemma game serves as a kind of model organism to help explore the issue. But other games, such as the . . .

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