The view that promise is the moral foundation of contract law is familiar in the philosophy of private law. Theorists use the promise principle to judge the justifiability of contract law doctrines, and debate whether existing doctrines converge or diverge from promissory morality. This is now known as the ‘contract and promise’ debate. This paper questions whether promise is the foundation of contract. We do not claim that some other principle serves as a foundation. Rather, we explore whether any single moral principle can serve as the foundation of contract. We distinguish three possible ways in which foundationalism can be understood (necessity, primacy and presumptiveness) and argue that they struggle to account for the interaction between the promise principle and other principles that are relevant to the determination of contractual claims. In light of these problems, we argue that to the extent that the individuation of contract law is a desirable end, it must be done on some other basis.
Letsas, George and Saprai, Prince, Foundationalism About Contract Law: A Sceptical View (July 10, 2018).