Mainstream economics in the context of "Economic surplus"

In economics, a production function gives the technological relation between quantities of physical inputs and quantities of output of goods. The production function is one of the key concepts of mainstream neoclassical theories, used to define marginal product and to distinguish allocative efficiency, a key focus of economics. One important purpose of the production function is to address allocative efficiency in the use of factor inputs in production and the resulting distribution of income to those factors, while abstracting away from the technological problems of achieving technical efficiency, as an engineer or professional manager might understand it.

For modelling the case of many outputs and many inputs, researchers often use the so-called Shephard's distance functions or, alternatively, directional distance functions, which are generalizations of the simple production function in economics.

In the history of economic thought, a school of economic thought is a group of economic thinkers who share or shared a mutual perspective on the way economies function. While economists do not always fit within particular schools, particularly in the modern era, classifying economists into schools of thought is common. Economic thought may be roughly divided into three phases: premodern (Greco-Roman, Indian, Persian, Islamic, and Imperial Chinese), early modern (mercantilist, physiocrats) and modern (beginning with Adam Smith and classical economics in the late 18th century, and Karl Marx and Friedrich Engels' Marxian economics in the mid 19th century). Systematic economic theory has been developed primarily since the beginning of what is termed the modern era.

Currently, the great majority of economists follow an approach referred to as mainstream economics (sometimes called 'orthodox economics'). Economists generally specialize into either macroeconomics, broadly on the general scope of the economy as a whole, or microeconomics, on specific markets or actors.

John Maynard Keynes, 1st Baron Keynes CB, FBA (/keɪnz/ KAYNZ; 5 June 1883 – 21 April 1946), was an English economist whose ideas fundamentally changed the theory and practice of macroeconomics and the economic policies of governments. Originally trained in mathematics, he built on and greatly refined earlier work on the causes of business cycles. One of the most influential economists of the 20th century, he produced writings that are the basis for the school of thought known as Keynesian economics, and its various offshoots. His ideas, reformulated as New Keynesianism, are fundamental to mainstream macroeconomics. He is known as the "father of macroeconomics".

Keynes was educated at King's College at the University of Cambridge, where he graduated in 1904 with a B.A. in mathematics. During the Great Depression of the 1930s, Keynes spearheaded a revolution in economic thinking, challenging the ideas of neoclassical economics that held that free markets would, in the short to medium term, automatically provide full employment, as long as workers were flexible in their wage demands. He argued that aggregate demand (total spending in the economy) determined the overall level of economic activity, and that inadequate aggregate demand could lead to prolonged periods of high unemployment, and since wages and labour costs are rigid downwards the economy will not automatically rebound to full employment. Keynes advocated the use of fiscal and monetary policies to mitigate the adverse effects of economic recessions and depressions. After the 1929 crisis, Keynes also turned away from a fundamental pillar of neoclassical economics: free trade. He criticized Ricardian comparative advantage theory (the foundation of free trade), considering the theory's initial assumptions unrealistic, and became definitively protectionist. He detailed these ideas in his magnum opus, The General Theory of Employment, Interest and Money, published in early 1936. By the late 1930s, leading Western economies had begun adopting Keynes's policy recommendations. Almost all capitalist governments had done so by the end of the two decades following Keynes's death in 1946. As a leader of the British delegation, Keynes participated in the design of the international economic institutions established after the end of World War II but was overruled by the American delegation on several aspects.

In mainstream economics, economic surplus, also known as total welfare or total social welfare or Marshallian surplus (after Alfred Marshall), is either of two related quantities:

• Consumer surplus, or consumers' surplus, is the monetary gain obtained by consumers because they are able to purchase a product for a price that is less than the highest price that they would be willing to pay.
• Producer surplus, or producers' surplus, is the amount that producers benefit by selling at a market price that is higher than the least that they would be willing to sell for; this is roughly equal to profit (since producers are not normally willing to sell at a loss and are normally indifferent to selling at a break-even price).

The sum of consumer and producer surplus is sometimes known as social surplus or total surplus; a decrease in that total from inefficiencies is called deadweight loss.

Milton Friedman (/ˈfriːdmən/ ; July 31, 1912 – November 16, 2006) was an American economist and statistician who received the 1976 Nobel Memorial Prize in Economic Sciences for his research on consumption analysis, monetary history and theory and the complexity of stabilization policy. With George Stigler, Friedman was among the intellectual leaders of the Chicago school of economics, a neoclassical school of economic thought associated with the faculty at the University of Chicago that rejected Keynesianism in favor of monetarism before shifting their focus to new classical macroeconomics in the mid-1970s. Several students, young professors and academics who were recruited or mentored by Friedman at Chicago went on to become leading economists, including Gary Becker (Nobel Prize 1992), Robert Fogel (Nobel Prize 1993), and Robert Lucas Jr. (Nobel Prize 1995).

Friedman's challenges to what he called "naive Keynesian theory" began with his interpretation of consumption, which tracks how consumers spend. He introduced a theory which would later become part of mainstream economics and he was among the first to propagate the theory of consumption smoothing. During the 1960s, he became the main advocate opposing both Marxist and Keynesian government and economic policies, and described his approach (along with mainstream economics) as using "Keynesian language and apparatus" yet rejecting its initial conclusions. He theorized that there existed a natural rate of unemployment and argued that unemployment below this rate would cause inflation to accelerate. He argued that the Phillips curve was in the long run vertical at the "natural rate" and predicted what would come to be known as stagflation. Friedman promoted a macroeconomic viewpoint known as monetarism and argued that a steady, small expansion of the money supply was the preferred policy, as compared to rapid and unexpected changes. His ideas concerning monetary policy, taxation, privatization, and deregulation influenced government policies, especially during the 1980s. His monetary theory influenced the Federal Reserve's monetary policy in response to the 2008 financial crisis.

Consumption refers to the use of resources to fulfill present needs and desires. It is seen in contrast to investing, which is spending for acquisition of future income. Consumption is a major concept in economics and is also studied in many other social sciences.

Different schools of economists define consumption differently. According to mainstream economists, only the final purchase of newly produced goods and services by individuals for immediate use constitutes consumption, while other types of expenditure — in particular, fixed investment, intermediate consumption, and government spending — are placed in separate categories (see consumer choice). Other economists define consumption much more broadly, as the aggregate of all economic activity that does not entail the design, production and marketing of goods and services (e.g., the selection, adoption, use, disposal and recycling of goods and services).

Marginal utility, in mainstream economics, describes the change in utility (pleasure or satisfaction resulting from the consumption) of one unit of a good or service. Marginal utility can be positive, negative, or zero. Negative marginal utility implies that every consumed additional unit of a commodity causes more harm than good, leading to a decrease in overall utility. In contrast, positive marginal utility indicates that every additional unit consumed increases overall utility.

In the context of cardinal utility, liberal economists postulate a law of diminishing marginal utility. This law states that the first unit of consumption of a good or service yields more satisfaction or utility than the subsequent units, and there is a continuing reduction in satisfaction or utility for greater amounts. As consumption increases, the additional satisfaction or utility gained from each additional unit consumed falls, a concept known as diminishing marginal utility. This idea is used by economics to determine the optimal quantity of a good or service that a consumer is willing to purchase.

Robert Gabriel Mugabe (/mʊˈɡɑːbi/; Shona: [muɡaɓe]; 21 February 1924 – 6 September 2019) was a Zimbabwean revolutionary and politician who served as the leader of Zimbabwe from 1980 until he was deposed in a coup in 2017. He served as the first Prime Minister of Zimbabwe from internationally recognised independence in 1980 to 1987, then as the second president of Zimbabwe from 1987 to 2017. He was also the Leader of the Zimbabwe African National Union (ZANU) from 1975 to 1980 and led its successor political party, the ZANU – Patriotic Front (ZANU–PF) as its First Secretary, from 1980 to 2017. Ideologically an African nationalist, during the 1970s and 1980s he identified as a Marxist–Leninist, and from the 1990s as a socialist.

Mugabe was born to a poor Shona family in Kutama, then in Southern Rhodesia. Educated at Kutama College and the University of Fort Hare, he worked as a schoolteacher. Angered by white minority rule of his homeland within the British Empire, Mugabe embraced Marxism and joined African nationalists calling for an independent state controlled by the black majority. After making antigovernmental comments, he was convicted of sedition and imprisoned between 1964 and 1974. On release, he fled to Mozambique, established his leadership of ZANU, and oversaw its role in the Rhodesian Bush War, fighting Ian Smith's predominantly white government. He reluctantly participated in peace talks in the United Kingdom that resulted in the Lancaster House Agreement, putting an end to the war. In the 1980 general election, Mugabe led ZANU-PF to victory, becoming prime minister when the country, now renamed Zimbabwe, gained internationally recognised independence later that year. Mugabe's administration expanded healthcare and education and—despite his professed desire for a socialist society—adhered largely to mainstream economic policies.