we cannot understand the human society and its logics unless we can understand institutions. As for this problem the philosophy and economics have different views. The complexity of institutions results in the multiple perspectives for studying institutions, which are the basis for the diversity of institutional theories. As for economists, they prefer the perspectives of behavior and normative account. As for philosophy, they prefer the perspective of cognition. These perspectives form the three main theories of institutional study, namely “rules account”, “equilibrium account”, and “constitutive rules account”. In trying to communicate the studies between the philosophy and economics, some scholars propose the unified theory of institutions. These proposals mainly integrate two or three of the three perspectives of institutional researches. Just as the contest in the unitary perspective of institutional researches, there also exist the different views about the unified theories of institution. The future of institutional researches depends on the cooperative relationship between the philosophy and economics, especially integrating the cognitive, behavior and normative perspective efficiently. At the same time, we also need to coordinate the individual and social dimensions of institutional research by understanding the institutions as social realities and social ontology.

Institutions, Rules, Equilibrium, Unified Theory