Over the course of the 1980s and the 1990s, macroeconomists coalesced around a paradigm known as the new neoclassical synthesis, which combines elements of both New Keynesian and New classical macroeconomics, and forms the basis for the current consensus, which covers previously disputed areas of macroeconomics. The consensus built around this synthesis is characterised by an unprecedented agreement on methodological questions (such as the need to validate models econometrically); such agreement had, until the new synthesis, historically eluded macroeconomics, even during the neoclassical synthesis. The financial crisis of 2007–2010 and the ensuing global economic crisis exposed modelling failures in the field of short-term macroeconomics. Term The term "mainstream economics" came into use in the late 20th century. It appeared in 2001 edition of the seminal textbook Economics by Samuelson and Nordhaus on the inside back cover in the "Family Tree of Economics," which depicts arrows into "Modern Mainstream Economics" from J.M. Keynes (1936) and neoclassical economics (1860–1910). The term "neoclassical synthesis" itself also first appears in the 1955 edition of Samuelson's textbook. Scope Mainstream economics can be defined, as distinct from other schools of economics, by various criteria, notably by its assumptions, its methods, and its topics. It is however also useful to challenge this distinction in light of the mutation of mainstream economics. Assumptions While being long rejected by many heterodox schools, several assumptions used to underpin many mainstream economic models. These include the neoclassical assumptions of rational choice theory, a representative agent, and, often, rational expectations. However, much of modern economic mainstream modeling consists of exploring the effects that complicating factors have on models, such as imperfect and asymmetric information, bounded rationality, incomplete markets, imperfect competition, heterogenous agents and transaction costs. Originally, the starting point of orthodox economic analysis was the individual. Individuals and firms were generally defined as units with a common goal: maximisation through rational behaviour. The only differences consisted of: the specific objective of the maximisation (individuals tend to maximise utility and firms profit); and the constraints faced in the process of maximisation (individuals might be constrained by limited income or commodity prices and firms might be constrained by technology or availability of inputs). From this (descriptive) theoretical framework, neoclassical economists like Alfred Marshall often derived - although not systematically - the political prescription that political action should not be used to solve the problems of the economic system. Instead, the solution ought to derive