He is the creator of economic norms theory, which identifies how sustained and equal opportunity in a market can create popular interests in liberal democracy, and peace within and between nations.
The prevalent mode of transaction is reciprocal exchange where favors are returned (or withheld) in the light of prior interactions, usually among small in-groups.
In contract-intensive societies individuals have an interest in all strangers having freedom of choice and being protected by reliably-impartial states – features that are essential for the proper functioning of an impersonal market.
As a consequence, contract-poor societies often lack stable and liberal democracy, and are often plagued with extensive rent seeking, corruption, and weak rule of law.
Consequently, contract-intensive nations not only avoid war with each other but engage in intense levels of mutual cooperation specifically aimed at promoting each other's material welfare.