Geoffrey Hodgson Defines Neoclassical Economics

I think he offers definitions in other works, too.

"Let us attempt to identify the key characteristics of neoclassical economics; the type of economices that has dominated the twentieth century. One of its exponents, Gary Becker (1967a, p. 5) identified its essence when he described 'the combined assumptions of maximizing behavior, market equilibrium, and stable preferences, used relentlessly and unflinchingly.' Accordingly, neoclassical economics may be conveniently defined as an approach which:

• (1) assumes rational, maximizing behaviour by agents with given and stable preference functions,
• (2) focuses on attained, or movements towards, equilibrium states, and
• (3) is marked by an absence of chronic information problems.

Point (3) requires some brief elaboration. In neoclassical economics, even if information is imperfect, information problems are typically overcome by using the concept of probabilistic risk. Excluded are phenomena such as severe ignorance and divergent perceptions by different individuals of a given reality. It is typically assumed that all individuals will interpret the same information in the same way, ignoring possible variations in the cognitive frameworks that are necessary to make sense of all data. Also excluded is uncertainty, of the radical type explored by Frank Knight (1921) and John Maynard Keynes (1936).

Notably, these three attributes are interconnected. For instance, the attainment of a stable optimum under (1) suggests an equilibrium (2); and rationality under (1) connotes the absence of severe information problems alluded to in (3). It can be freely admitted that some recent developments in modern economic theory - such as in game theory - reach to or even lie outside the boundaries of this definitions. Their precise placement will depend on inspection and refinement of the boundary conditions in the above clauses. But that does not undermine the usefulness of this rough and ready definition.

Although neoclassical economics has dominated the twentieth century, it has changed radically in tone and presentation, as well as in content. Until the 1930s, much neoclassical analysis was in Marshallian, partial equilibrium mode. The following years saw the revival of Walrasian general equilibrium analysis, an approach originally developed in the 1870s. Another transformation during this century has been the increasing use of mathematics, as noted in the preceding chapter. Neoclassical assumptions have proved attractive because of their apparent tractability. To the mathematically inclined economist the assumption that agents are maximizing an exogeneously given and well defined preference function seems preferable to any alternative or more complex model of human behaviour. In its reductionist assumptions, neoclassical economics has contained within itself from its inception an overly formalistic potential, even if this took some time to become fully realized and dominant. Gradually, less and less reliance has been placed on the empirical or other grounding of basic assumptions, and more on the process of deduction from premises that are there simply because they are assumed.

Nevertheless, characteristics (1) to (3) above have remained prominent in mainstream economics from the 1870s to the 1980s. They define an approach that still remains ubiquitous in the economics textbooks and is taught to economics undergraduates throughout the world." -- Geoffrey M. Hodgson (1999). "False Antagonisms and Doomed Reconcilations", Chapter 2 in Evolution and Institutions: On Evolutionary Economics and the Evolution of Economics, Edward Elgar