Modern economic thought is usually said to have begun with
Adam Smith in the late 18th century. For an overview of precursors
to Smith as well as an overview of schools that have developed
later, see history of economic thought. Modern mainstream
economics is primarily a further refinement of neoclassical
Macroeconomics began with Keynes in the 1930s. For an overview
of a number of competing schools, see macroeconomics.
Many economists use a combination of Neoclassical microeconomics
and Keynesian macroeconomics. This combination, sometimes
known as the Neoclassical synthesis, was dominant in Western
teaching and public policy in the years following World War
II and up to the late 1970s.
In principle, economics can be applied to any type of economic
organization. However, it developed historically in market
societies, and its most detailed and precise work has dealt
with the institutions belonging to them. To what extent economics
must be adjusted to be applied to earlier forms of social
organization has been the source of discussion. Generally,
mainstream economists mostly feel that the basic framework
of economics is relevant and flexible enough to be applied
to virtually any form of society. Marxist economists, who
were more influential a few decades ago, often feel that each
era of history obeys its very own set of laws, and that contemporary
economics can only be applied to industrialized societies.