… is from pages 9-10 of the Introduction by Fred S. McChesney and William F. Shughart to their invaluable 1995 collection, The Causes and Consequence of Antitrust: The Public Choice Perspective:
Homo politicus and homo economicus are the same. The critical implication of this assumption of universal self-interest is that the observed differences between public choices and private choices emerge not because individuals adopt different behavioral objectives in the two settings, but rather because the constraints on behavior are different. Different outcomes emerge not because public choices are guided by motives different from those guiding private choices, but rather because in private markets self-interested voters and politicians make choices that mainly affect themselves, while in political markets self-interested voters and politicians make choices that mainly affect others.
DBx: As mentioned in earlier posts (for example, this one), at the heart of public choice is the assumption that people in all different institutional settings are fundamentally the same; their motivations – their degrees of self-interest – are the same when they act in private market settings as when they act in political settings. It is true that in most public-choice scholarship the assumption is made that each individual is motivated by a significant degree of concern for his or her own material and emotional well-being. I believe that this assumption is true to reality. But even if we use the assumption that individuals are much more saintly – much less self-interested – than we typically observe in reality, public-choice analysis would still predict different patterns of choices emerging from different institutional settings.