David Ricardo in the context of "Heckscher–Ohlin model"

Classical economics, also known as the classical school of economics, or classical political economy, is a school of thought in political economy that flourished, primarily in Britain, in the late 18th and early-to-mid 19th century. It includes both the Smithian and Ricardian schools. Its main thinkers are held to be Adam Smith, Jean-Baptiste Say, David Ricardo, Thomas Robert Malthus, and John Stuart Mill. These economists produced a theory of market economies as largely self-regulating systems, governed by natural laws of production and exchange (famously captured by Adam Smith's metaphor of the invisible hand).

Adam Smith's The Wealth of Nations in 1776 is usually considered to mark the beginning of classical economics. The fundamental message in Smith's book was that the wealth of any nation was determined not by the gold in the monarch's coffers, but by its national income. This income was in turn based on the labor of its inhabitants, organized efficiently by the division of labour and the use of accumulated capital, which became one of classical economics' central concepts.

Labour power (German: Arbeitskraft; French: force de travail) is the capacity to work, a key concept used by Karl Marx in his critique of capitalist political economy. Marx distinguished between the capacity to do the work, i.e. labour power, and the physical act of working, i.e. labour. Human labour power exists in any kind of society, but on what terms it is traded or combined with means of production to produce goods and services has historically varied greatly.

The general idea of labour-power had existed previously in classical political economy. Adam Smith's The Wealth of Nations and David Ricardo's On the Principles of Political Economy and Taxation already referred to the "productive powers of labour". However, Marx made the concept much more precise, critically examining the functions of labour-power in production, how labour-power is used, organized and exploited, and how it is typically valued and priced in bourgeois society.

Comparative advantage in an economic model is the advantage over others in producing a particular good. A good can be produced at a lower relative opportunity cost or autarky price, i.e. at a lower relative marginal cost prior to trade. Comparative advantage describes the economic reality of the gains from trade for individuals, firms, or nations, which arise from differences in their factor endowments or technological progress.

David Ricardo developed the classical theory of comparative advantage in 1817 to explain why countries engage in international trade even when one country's workers are more efficient at producing every single good than workers in other countries. He demonstrated that if two countries capable of producing two commodities engage in the free market (albeit with the assumption that the capital and labour do not move internationally), then each country will increase its overall consumption by exporting the good for which it has a comparative advantage while importing the other good, provided that there exist differences in labor productivity between both countries. Widely regarded as one of the most powerful yet counter-intuitive insights in economics, Ricardo's theory implies that comparative advantage rather than absolute advantage is responsible for much of international trade.

Income inequality metrics or income distribution metrics are used by social scientists to measure the distribution of income and economic inequality among the participants in a particular economy, such as that of a specific country or of the world in general. While different theories may try to explain how income inequality comes about, income inequality metrics simply provide a system of measurement used to determine the dispersion of incomes. The concept of inequality is distinct from poverty and fairness.

Income distribution has always been a central concern of economic theory and economic policy. Classical economists such as Adam Smith, Thomas Malthus and David Ricardo were mainly concerned with factor income distribution, that is, the distribution of income between the main factors of production, land, labour and capital. It is often related to wealth distribution, although separate factors influence wealth inequality.

In classical political economy and especially Karl Marx's critique of political economy, a commodity is any good or service ("products" or "activities") produced by human labour and offered as a product for general sale on the market. Some other priced goods are also treated as commodities, e.g. human labor-power, works of art and natural resources, even though they may not be produced specifically for the market, or be non-reproducible goods. This problem was extensively debated by Adam Smith, David Ricardo, and Karl Rodbertus-Jagetzow, among others. Value and price are not equivalent terms in economics, and theorising the specific relationship of value to market price has been a challenge for both liberal and Marxist economists.

A land value tax (LVT) is a levy on the value of land without regard to buildings, personal property and other improvements upon it. Some economists favor LVT, arguing it does not cause economic inefficiency, and helps reduce economic inequality. A land value tax is a progressive tax, in that the tax burden falls on land owners, because land ownership is correlated with wealth and income. The land value tax has been referred to as "the perfect tax" and the economic efficiency of a land value tax has been accepted since the eighteenth century. Economists since Adam Smith and David Ricardo have advocated this tax because it does not hurt economic activity, and encourages development without subsidies.

LVT is associated with Henry George, whose ideology became known as Georgism. George argued that taxing the land value is the most logical source of public revenue because the supply of land is fixed and because public infrastructure improvements would be reflected in (and thus paid for by) increased land values.

The labor theory of value (LTV) is a theory of value that argues that the exchange value of a good or service is determined by the total amount of "socially necessary labor" required to produce it. The contrasting system is typically known as the subjective theory of value.

The LTV is usually associated with Marxian economics, although it originally appeared in the theories of earlier classical economists such as Adam Smith and David Ricardo, and later in anarchist economics. Smith saw the price of a commodity as a reflection of how much labor it can "save" the purchaser. The LTV is central to Marxist theory, which holds that capitalists' expropriation of the surplus value produced by the working class is exploitative. Modern mainstream economics rejects the LTV and uses a theory of value based on subjective preferences.

The law of the value of commodities (German: Wertgesetz der Waren), known simply as the law of value, is a central concept in Karl Marx's critique of political economy first expounded in his polemic The Poverty of Philosophy (1847) against Pierre-Joseph Proudhon with reference to David Ricardo's economics. Most generally, it refers to a regulative principle of the economic exchange of the products of human work, namely that the relative exchange-values of those products in trade, usually expressed by money-prices, are proportional to the average amounts of human labor-time which are currently socially necessary to produce them (see Socially necessary labour time) within the capitalist mode of production.

Thus, the fluctuating exchange value of commodities (exchangeable products) is regulated by their value, where the magnitude of their value is determined by the average quantity of human labour which is currently socially necessary to produce them (see labor theory of value and value-form). Theorizing this concept and its implications preoccupied Marx for more than two decades.

Socially necessary labour time in Marx's critique of political economy is what regulates the exchange value of commodities in trade. In short, socially necessary labour time refers to the average quantity of labour time that must be performed under currently prevailing conditions to produce a commodity.

Unlike individual labour hours in the classical labour theory of value formulated by Adam Smith and David Ricardo, Marx's exchange value is conceived as a proportion (or 'aliquot part') of society's labour-time.