Reciprocity I: the requirement of exchange

Abstract

This chapter explains the central role of reciprocity in contract law through the doctrine of consideration. It explores why enforceability depends on the exchange of value rather than mere promise: it tracks universal moral codes, channels contracts into acceptable patterns inhibiting exploitation, signals mutually respectful treatment between strangers, and draws crucial boundaries between market and private domains where implicit reciprocity, trust, and extra-legal sanctions operate differently, reflecting fundamentally different relationship contexts. While civil law ostensibly dispenses with consideration, practical differences are smaller than appearances suggest—both systems enforce exchanges readily, but subject gratuitous promises to stringent formality requirements. Valid consideration need not be adequate, with nominal consideration sufficing, but must be causally connected and not past. Pre-existing duties generally don’t constitute consideration, though exceptions protect vulnerable parties and permit same-for-more variations when commercially expedient.