Reciprocal Altruism as the Basis for Contract

58 Pages Posted: 26 Sep 2008 Last revised: 31 Mar 2014

Edwin S. Fruehwald


Date Written: September 18, 2008


Behavioral Biology illuminates the basis of contract. Behavioral biologists believe that genes are selfish; they are only interested in their survival. However, reciprocal altruism - "I'll scratch your back if you scratch mine" - provides a basis for cooperation among humans that promotes survival. If two humans cooperate in obtaining and allocating resources, they will have greater resources and a greater chance to survive and reproduce, thus continuing their genes. Contract law reflects and reinforces this reciprocal altruism from our evolutionary past.

Connected with reciprocal altruism is a human instinct for equity in reciprocal exchanges. Humans can detect unfair situations and rectify them. Evolutionary fairness is reflected in the contract rules of frustration, unconscionability, and mistake, as well as the good faith duty in performance and unconscionability. Also connected with reciprocal altruism is the need to punish cheaters. In contract law, cheaters - those who breach the contract - are punished through contract remedies. Finally, contract law helps deal with the evolutionary problem of time-shifted rationality, where individuals value what they have over what they can gain in the future.

Part II of this paper will discuss traditional theories of contract law, including the objective theory of contract formation, deontological and consequentialist approaches, redistributive theories, and more recent theories by Professor Solan (contract as agreement) and Professor Markovits (contract as collaboration). Part III will introduce behavioral biology and explain reciprocal altruism and related doctrines, such as cheating and time-shifted rationality. It will also show that neuroscientific studies support the existence of reciprocal altruism and related behavioral mechanisms. Part IV will then analyze the relationship between reciprocal altruism and contract law. It will argue that reciprocal altruism is the best explanation for the formation of contracts, compare reciprocal altruism as the basis of contract to the theories discussed in Part II, examine the other necessary element for contract validity - consideration - under reciprocal altruism, and give a justification for courts to enforce contracts under reciprocal altruism. Part V will demonstrate that contract damages are the glue for reciprocal altruism and that expectation damages are the proper measure of damages under this approach. Finally, Part VI will deal with reciprocal altruism and other contract issues-gap filling, unallocated risks, good faith in performance, and unconscionability.

Keywords: contract, behavioral biology, jurisprudence

Suggested Citation

Fruehwald, Edwin S., Reciprocal Altruism as the Basis for Contract (September 18, 2008). University of Louisville Law Review, Vol. 47, No. 3, 2009; Hofstra Univ. Legal Studies Research Paper No. 08-09. Available at SSRN:

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