… is from page 44 of Jim Buchanan’s 1977 collection, Freedom in Constitutional Contract; specifically, it’s from Jim’s 1974 essay “Good Economics – Bad Law” (which is a review of the first edition of Richard Posner’s Economic Analysis of Law) (original emphasis):
The market economy’s sociopolitical function is that of minimizing the necessity of resorting to internal ethical constraints on human behavior and/or external legal-governmental-political restrictions. To the extent that men are allowed freely to trade, conceived in the broadest possible sense of the term, there is little need for the preacher or the administrative authority.
