The father of modern economics, Adam Smith, was conscious of the relationship between law and economics as evident in his writings on mercantile law. While his manuscripts were destroyed upon his death, historians speculate that he was following up on his magnum opus, The Wealth of Nations, with another book on the history and theory of law. One might wonder how law and economics would have developed if he had finished his work.

The two disciplines continued separately centred on two personae, "the rational man" in economics, and the "the reasonable man" in law. While the yardstick of reasonableness is the norms and shared values of society, rationality is a matter of finding the most efficient means to an end - of maximising value.