The main objective of this paper is to explore what we call the “social theory” or the “social philosophy” that presumably shapes, inspires and defines the Ostroms’ research program. Our argument is that what we have called the “social theory” behind the Bloomington School’s research agenda has in fact two facets that may or may not be consistent with each other. Even more, they may or may not be necessarily and inseparably connected with the rest of the program. The first is built around the concept of “polycentricity” and a series of Public Choice insights, and is a challenge to two of the deepest assumptions of political and economic sciences in the 20th century: the monocentric vision of social order and the “market” versus “state” dichotomy. The second is built around a view of social order seen as a knowledge and learning process, along with a series of observations about the human condition, fallibility, coercion and error as well as about the factors engendering institutional order as a response to the challenges posed by them.