We give examples of strategic interaction which are beneficial for players who follow a "middle path" of balance between pure selfishness and pure altruism. JEL Classification: C70, C71, C72, C79.

In a society of completely selfish individuals where everybody is only interested in maximizing his own payoff, does any equilibrium exist for the society? John Nash proved more than 50 years ago that an equilibrium always exists such that nobody would benefit from unilaterally changing his strategy. Nash Equilibrium is a central concept in game theory, which offers a mathematical foundation fo...

The replication control genes of bacterial plasmids face selection at two conflicting levels. Plasmid copies that systematically overreplicate relative to their cell mates have a higher chance of fixing in descendant cells, but these cells typically have a lower chance of fixing in the population. Apart from identifying the conflict, this mathematical discussion characterizes the efficiency of ...

We compare behavior in modified dictators game during the “Great Recession” to behavior in otherwise identical experiments conducted amidst the economic boom that preceded it. The experiments capture both differences in indexical selfishness and differences in equalityefficiency tradeoffs. Subjects exposed to the recession exhibit higher levels of indexical selfishness and greater emphasis on e...

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Altruism refers to a willingness to benefit others, even at one’s own expense. In contrast, selfishness refers to prioritizing one’s own interests with no consideration for others. However, even if an agent is selfish, he might nevertheless act as if he were altruistic out of selfish concerns triggered when his action is observed; that is, he might seek to feel pride in acting altruistically an...

Individual success in group-structured populations has two components. First, an individual gains by outcompeting its neighbours for local resources. Second, an individual's share of group success must be weighted by the total productivity of the group. The essence of sociality arises from the tension between selfish gains against neighbours and the associated loss that selfishness imposes by d...

Some 35 years ago, the Club of Rome pub­ lished a book that sold more than 30 million copies across 30 different translations (Donella Meadows et al. 1972). The book predicted the collapse of modern society if population growth, resource depletion, and pollution proceeded unabated. More recently, the Millennium Eco­ system Assessment echoed similar sentiments, documenting the loss of vital ecos...