<P> According to ecological economist Malte Faber, ecological economics is defined by its focus on nature, justice, and time . Issues of intergenerational equity, irreversibility of environmental change, uncertainty of long - term outcomes, thermodynamics limits to growth, and sustainable development guide ecological economic analysis and valuation . </P> <P> Energy accounting was proposed in the early 1930s as a scientific alternative to a price system, or money method of regulating society . Joseph Tainter suggests that a diminishing ratio of energy returned on energy invested is a chief cause of the collapse of complex societies . Falling EROEI due to depletion of non-renewable resources also poses a difficult challenge for industrial economies . Sustainability becomes an issue as survival is threatened due to climate change . </P> <P> In 1919 Yale economist Walton H. Hamilton coined the term "Institutional economics". In 1934 John R. Commons (1862--1945), another economist from midwestern America published Institutional Economics (1934), based on the concept that the economy is a web of relationships between people with diverging interests, including monopolies, large corporations, labor disputes, and fluctuating business cycles . They do however have an interest in resolving these disputes . Government, thought Commons, ought to be the mediator between the conflicting groups . Commons himself devoted much of his time to advisory and mediation work on government boards and industrial commissions . </P> <P> In 1920 Alfred Marshall's student Arthur Cecil Pigou (1877--1959) published Wealth and Welfare, which insisted on the possibility of market failures, claiming that markets are inefficient in the case of economic externalities, and the state must interfere to prevent them . However, Pigou retained free market beliefs, and in 1933, in the face of the economic crisis, he explained in The Theory of Unemployment that the excessive intervention of the state in the labor market was the real cause of massive unemployment because the governments had established a minimal wage, which prevented wages from adjusting automatically . This was to be the focus of attack from Keynes . In 1943 Pigou published the paper The Classical Stationary State, which popularized the Pigou (Real Balance) Effect, the stimulation of output and employment during deflation by increasing consumption due to a rise in wealth </P>

Where did economics as a body of thought originate