Pareto efficiency

In microeconomics, economic efficiency, depending on the context, is usually one of the following two related concepts:

• Allocative or Pareto efficiency: any changes made to assist one person would harm another.
• Productive efficiency: no additional output of one good can be obtained without decreasing the output of another good, and production proceeds at the lowest possible average total cost.

These definitions are not equivalent: a market or other economic system may be allocatively but not productively efficient, or productively but not allocatively efficient. There are also other definitions and measures. All characterizations of economic efficiency are encompassed by the more general engineering concept that a system is efficient or optimal when it maximizes desired outputs (such as utility) given available inputs.

A Pigouvian tax (also spelled Pigovian tax) is a tax on a market activity which is generating negative externalities, that is, costs incurred by third parties. It imposes costs corresponding with the externalities, internalizing those costs to improve Pareto efficiency. Ideally, the tax is set equal to the external marginal cost of the negative externalities, in order to correct an undesirable or inefficient market outcome (a market failure).

In the presence of negative externalities, parties who did not consent to the transaction or activity, and did not receive payment, nevertheless incur some of the costs, so the total cost is not covered by the private cost of the activity. In such a case, the market outcome is not efficient and may lead to a harmful excess of the activity. Examples of negative externalities are environmental pollution and increased public healthcare costs associated with tobacco and sugary drink consumption.

In welfare economics, the theory of the second best concerns the situation when one or more optimality conditions cannot be satisfied. The economists Richard Lipsey and Kelvin Lancaster showed in 1956 that if one optimality condition in an economic model cannot be satisfied, it is possible that the next-best solution involves changing other variables away from the values that would otherwise be optimal. Politically, the theory implies that if it is infeasible to remove a particular market distortion, introducing one or more additional market distortions in an interdependent market may partially counteract the first, and lead to a more efficient outcome.

Criticism of socialism is any critique of socialist economics and socialist models of organization and their feasibility, as well as the political and social implications of adopting such a system. Some critiques are not necessarily directed toward socialism as a system but rather toward the socialist movement, parties, or existing states. Some critics consider socialism to be a purely theoretical concept that should be criticized on theoretical grounds, such as in the economic calculation problem and the socialist calculation debate, while others hold that certain historical examples exist and that they can be criticized on practical grounds. Because there are many types of socialism, most critiques are focused on a specific type of socialism, that of the command economy and the experience of Soviet-type economies that may not apply to all forms of socialism. Different models of socialism conflict with each other over questions of property ownership, economic coordination and how socialism is to be achieved. Critics of specific models of socialism might be advocates of a different type of socialism.

According to the Austrian School economist Ludwig von Mises, an economic system (specifically centralized economic planning) that does not use money, financial calculation, and market pricing would be unable to effectively value capital goods and coordinate production, and therefore in his view socialism is impossible because it lacks the necessary information to perform economic calculation in the first place. Another central argument leveled against socialist systems based on economic planning is based on the use of dispersed knowledge. Socialism is unfeasible in this view because information cannot be aggregated by a central body and effectively used to formulate a plan for an entire economy, because doing so would result in distorted or absent price signals; this is known as the economic calculation problem. Other economists criticize models of socialism based on neoclassical economics for their reliance on the faulty and unrealistic assumptions of economic equilibrium and Pareto efficiency.

Vilfredo Federico Damaso Pareto (/pəˈreɪtoʊ/; Italian: [paˈreːto]; born Wilfried Fritz Pareto; 15 July 1848 – 19 August 1923) was an Italian polymath, whose areas of interest included sociology, civil engineering, economics, political science, and philosophy. He made several important contributions to economics, particularly in the study of income distribution and in the analysis of individuals' choices, and was one of the minds behind the Lausanne School of economics. He was also responsible for popularising the use of the term elite in social analysis and contributed to elite theory. He has been described as "one of the last Renaissance scholars. Trained in physics and mathematics, he became a polymath whose genius radiated into nearly all other major fields of knowledge."

He introduced the concept of Pareto efficiency and helped develop the field of microeconomics. He was also the first to claim that income follows a Pareto distribution, which is a power law probability distribution. The Pareto principle was named after him, and it was built on his observations that 80% of the wealth in Italy belonged to about 20% of the population. He also contributed to the fields of mathematics and sociology.

The Lange model (or Lange–Lerner theorem) is a neoclassical economic model for a hypothetical socialist economy based on public ownership of the means of production and a trial-and-error approach to determining output targets and achieving economic equilibrium and Pareto efficiency. In this model, the state owns non-labor factors of production, and market simulations are used by the planning organs to allocate final goods and consumer goods. The Lange model states that if all production is performed by a public body such as a democratic state, and there is a functioning price mechanism, this economy will be Pareto-efficient, like a hypothetical market economy under perfect competition. Unlike models of capitalism, the Lange model is based on direct allocation, by directing enterprise managers to set price equal to marginal cost in order to achieve Pareto efficiency. By contrast, in a capitalist economy, private owners seek to maximize profits, while competitive pressures are relied on to indirectly lower the price; this discourages production with high marginal cost and encourages economies of scale.

This model was first proposed by Oskar R. Lange in 1936 during the socialist calculation debate, and was expanded by economists like H. D. Dickinson and Abba P. Lerner. Although Lange and Lerner called it "market socialism", the Lange model is a form of centrally planned economy where a central planning board allocates investment and capital goods, while markets allocate labor and consumer goods. The planning board simulates a market in capital goods by a trial-and-error process first elaborated by Vilfredo Pareto and Léon Walras. The Lange Model is in practice a type of centrally planned economy and not a type of market socialism.