Wikipedia
Institutional economics focuses on understanding the role of the evolutionary process and the role of institutions in shaping economic behaviour. Its original focus lay in Thorstein Veblen's instinct-oriented dichotomy between technology on the one side and the "ceremonial" sphere of society on the other. Its name and core elements trace back to a 1919 American Economic Review article by Walton H. Hamilton.
Institutional economics emphasizes a broader study of institutions and views markets as a result of the complex interaction of these various institutions (e.g. individuals, firms, states, social norms). The earlier tradition continues today as a leading heterodox approach to economics.
A significant variant is the new institutional economics from the later 20th century, which integrates later developments of neoclassical economics into the analysis. Law and economics has been a major theme since the publication of the Legal Foundations of Capitalism by John R. Commons in 1924. Since then, there is heated debate on the role of law (formal institution) on economic growth, Behavioral economics is another hallmark of institutional economics based on what is known about psychology and cognitive science, rather than simple assumptions of economic behavior.
Institutional economics focuses on learning, bounded rationality, and evolution (rather than assume stable preferences, rationality and equilibrium). It was a central part of American economics in the first part of the 20th century, including such famous but diverse economists as Thorstein Veblen, Wesley Mitchell, and John R. Commons. Some institutionalists see Karl Marx as belonging to the institutionalist tradition, because he described capitalism as a historically-bounded social system; other institutionalist economists disagree with Marx's definition of capitalism, instead seeing defining features such as markets, money and the private ownership of production as indeed evolving over time, but as a result of the purposive actions of individuals.
"Traditional" institutionalism rejects the reduction of institutions to simply tastes, technology, and nature (see naturalistic fallacy). Tastes, along with expectations of the future, habits, and motivations, not only determine the nature of institutions but are limited and shaped by them. If people live and work in institutions on a regular basis, it shapes their world-views. Fundamentally, this traditional institutionalism (and its modern counterpart institutionalist political economy) emphasizes the legal foundations of an economy (see John R. Commons) and the evolutionary, habituated, and volitional processes by which institutions are erected and then changed (see John Dewey, Thorstein Veblen, and Daniel Bromley.)
The vacillations of institutions are necessarily a result of the very incentives created by such institutions, and are thus endogenous. Emphatically, traditional institutionalism is in many ways a response to the current economic orthodoxy; its reintroduction in the form of institutionalist political economy is thus an explicit challenge to neoclassical economics, since it is based on the fundamental premise that neoclassicists oppose: that economics cannot be separated from the political and social system within which it is embedded.
Some of the authors associated with this school include Robert H. Frank, Warren Samuels, Mark Tool, Geoffrey Hodgson, Daniel Bromley, Jonathan Nitzan, Shimshon Bichler, Elinor Ostrom, Anne Mayhew, John Kenneth Galbraith and Gunnar Myrdal, but even the sociologist C. Wright Mills was highly influenced by the institutionalist approach in his major studies.