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Post Keynesian economics is a school of economic thought that developed in the decades after John Maynard Keynes’s The General Theory of Employment, Interest and Money (1936), but it is not simply the economics of Keynes himself. It is a distinct research programme that rejects the neoclassical synthesis—the attempt by later economists to reconcile Keynes’s ideas with the classical theory of general equilibrium—and instead builds on the more radical, uncertain, and historically grounded elements of Keynes’s work. Post Keynesians study how capitalist economies actually function in historical time, with a particular focus on the role of money, effective demand, fundamental uncertainty, and the distribution of income. The field is unified less by a single doctrine than by a shared opposition to the core assumptions of mainstream economics: that economies tend toward full employment, that agents have perfect knowledge, and that money is a neutral veil over real transactions.
The central question of Post Keynesian economics is why capitalist economies experience persistent unemployment, instability, and crisis, and what policies can address these problems. Where mainstream economics treats unemployment as a temporary deviation from a natural equilibrium, Post Keynesians argue that unemployment is the normal state of a monetary production economy. The stakes are practical as well as theoretical: if unemployment is not self-correcting, then government intervention—through fiscal policy, monetary policy, and institutional reform—is not a distortion of an otherwise efficient market but a necessary condition for economic stability and social welfare.
A second central question concerns the nature of money. Post Keynesians reject the view that money is a commodity that evolved to facilitate barter, or a veil that merely reflects real transactions. Instead, money is a social institution created by the state and by banks through the act of lending. This leads to the theory of endogenous money: the money supply is not controlled by the central bank but is determined by the demand for bank credit. The central bank sets the interest rate, but it cannot directly control the quantity of money. This has profound implications for monetary policy, inflation, and the relationship between finance and the real economy.
A third question concerns time and uncertainty. Post Keynesians distinguish between risk, where probabilities are known, and fundamental uncertainty, where the future is not merely unknown but unknowable. In a world of fundamental uncertainty, economic decisions—especially investment decisions—cannot be reduced to rational calculation. They depend on conventions, animal spirits, and expectations that can shift abruptly. This makes the economy inherently unstable and explains why financial markets, far from being efficient allocators of capital, can amplify shocks and generate crises.
Post Keynesian economics emerged in the 1950s and 1960s as a reaction to the neoclassical synthesis, which had domesticated Keynes’s theory by presenting it as a special case of classical economics—a case where sticky wages and prices prevented the economy from reaching full employment. For a group of economists centred at Cambridge University in England, this was a fundamental misreading. Led by Joan Robinson, Nicholas Kaldor, Richard Kahn, and Piero Sraffa, they argued that Keynes had challenged the very foundations of classical theory, not merely added a friction to it.
The term “Post Keynesian” was coined in the early 1970s to distinguish this group from the “neo-Keynesians” who had built the synthesis. The Cambridge economists were also engaged in a parallel debate with the neoclassical theory of capital—the so-called Cambridge capital controversies—in which they showed that the aggregate production function, a cornerstone of mainstream economics, was logically incoherent. This debate, which raged in the 1960s, demonstrated that the distribution of income between wages and profits could not be explained by the marginal productivity of factors, but depended instead on social and institutional forces, including the bargaining power of workers and the investment decisions of capitalists.
A second major strand of Post Keynesian thought developed in the United States, associated with economists such as Hyman Minsky, Paul Davidson, and Sidney Weintraub. Minsky’s financial instability hypothesis argued that capitalist economies are inherently prone to boom-and-bust cycles driven by the accumulation of debt. During periods of stability, firms and banks become increasingly leveraged, moving from hedge finance (where cash flows cover debt payments) to speculative finance (where cash flows cover interest but not principal) to Ponzi finance (where cash flows cover neither). Eventually, the fragility of the financial system leads to a crisis. Minsky’s work, largely ignored during the postwar boom, gained renewed attention after the 2008 global financial crisis.
The American and British strands of Post Keynesianism differed in emphasis. The British school, influenced by Sraffa and the classical economists, focused on the theory of value, distribution, and the long period. The American school, influenced by Minsky and Davidson, focused on money, finance, and the short period. These differences were never fully reconciled, and they remain a source of internal tension within the field.
Post Keynesian economics is not a monolithic school but a family of approaches that share a common core while disagreeing on important details. The main approaches can be distinguished by their treatment of value theory, their view of the long run, and their attitude toward other heterodox traditions.
The fundamentalist Keynesians, represented most prominently by Paul Davidson, argue that the essential message of Keynes’s General Theory lies in its treatment of uncertainty and money. For Davidson, the key distinction is between an economy in which the future can be probabilistically known (the classical world) and one in which it cannot (the Keynesian world). In the latter, money is not neutral because it is the means by which agents protect themselves from uncertainty. Holding money is a way of postponing decisions in a world where the future is unknowable. This approach emphasizes the non-ergodic nature of economic processes: the statistical properties of the past do not reliably predict the future. Fundamentalist Keynesians are therefore critical of any attempt to reduce Keynes’s theory to a set of equations that can be estimated from historical data, since such estimation assumes the very stability that Keynes denied.
The strength of this approach is its fidelity to Keynes’s own writings and its clear articulation of the philosophical foundations of Post Keynesian economics. Its limitation is that it is primarily a critique of mainstream economics rather than a positive research programme. It offers few tools for analysing the specific dynamics of capitalist economies beyond the general proposition that they are unstable.
The Sraffian approach, named after Piero Sraffa’s Production of Commodities by Means of Commodities (1960), focuses on the theory of value and distribution. Sraffa showed that the relative prices of commodities and the rate of profit could be determined simultaneously from the technical conditions of production and the wage rate, without any appeal to marginal productivity or supply and demand. This provided a rigorous foundation for the classical theory of value, which had been displaced by the marginalist revolution of the 1870s.
Sraffians argue that the neoclassical theory of distribution is logically incoherent, as demonstrated in the capital controversies. They also argue that the long-period method—the analysis of the centre of gravity around which actual prices and quantities fluctuate—is the appropriate way to understand capitalist economies. This puts them at odds with fundamentalist Keynesians, who emphasize short-period analysis and the role of expectations. Sraffians are also critical of the labour theory of value, which they see as unnecessary for the determination of prices and profits.
The strength of the Sraffian approach is its analytical rigour and its connection to the classical tradition of Adam Smith, David Ricardo, and Karl Marx. Its limitation is that it is a theory of value and distribution, not a theory of output and employment. Sraffians have little to say about the dynamics of investment, money, and finance, and they have been accused of neglecting the very issues that Keynes placed at the centre of economics.
The Kaleckian approach, based on the work of Michał Kalecki, combines elements of Keynes and Marx. Kalecki, a Polish economist who independently developed many of Keynes’s ideas, argued that the level of output is determined by the investment decisions of capitalists, and that profits are determined by spending. His famous aphorism—"workers spend what they get, capitalists get what they spend"—captures the idea that the distribution of income between wages and profits is determined by the level of aggregate demand, not by marginal productivity.
Kaleckian models are typically expressed in terms of the degree of monopoly, the mark-up of prices over costs, and the utilization of capacity. They allow for the possibility that a redistribution of income from profits to wages can increase output and employment—the so-called wage-led growth regime—or decrease it, depending on the relative propensities to consume and the responsiveness of investment to profits. This approach has been highly influential in the analysis of the relationship between income distribution and economic growth, and it has been extended by economists such as Amit Bhaduri and Stephen Marglin.
The strength of the Kaleckian approach is its combination of class analysis with effective demand. It provides a framework for understanding how the distribution of income affects the level of economic activity, and vice versa. Its limitation is that it tends to be static, focusing on the equilibrium of the system rather than its dynamics. It also has difficulty incorporating the role of money and finance, which are central to the Minskyan strand of Post Keynesianism.
The Minskyan approach, based on the work of Hyman Minsky, focuses on the role of finance in generating economic instability. Minsky argued that the financial system is inherently fragile because stability breeds instability: as the economy grows, firms and banks become increasingly willing to take on debt, and the structure of financial commitments becomes more fragile. This process is not a deviation from equilibrium but a normal feature of capitalist development.
Minsky’s financial instability hypothesis has been formalized in a variety of ways, but its core insight is that the interaction between real investment and financial commitments can generate endogenous cycles of boom and bust. The approach has been particularly influential in the analysis of financial crises, and it has been combined with the Kaleckian approach to produce models of "financialized" capitalism, in which the growth of the financial sector has outpaced the growth of the real economy.
The strength of the Minskyan approach is its attention to the monetary and financial dimensions of capitalism, which are often neglected in other Post Keynesian approaches. Its limitation is that it is primarily a theory of crisis, not a theory of normal functioning. It has little to say about the determination of prices, the distribution of income, or the long-run trajectory of the economy.
A final strand of Post Keynesianism is closely connected to American institutionalism, the tradition of Thorstein Veblen, John R. Commons, and Wesley Clair Mitchell. Institutionalist Post Keynesians emphasize the role of habits, conventions, and power in shaping economic behaviour. They are critical of the abstract, ahistorical models of mainstream economics and argue that economic analysis must be grounded in the specific institutions of a particular time and place.
This approach has been influential in the analysis of labour markets, corporate governance, and the welfare state. It has also been important in the development of the theory of the firm, where Post Keynesians argue that firms do not maximize profits in the neoclassical sense but pursue a variety of goals, including growth, market share, and survival, subject to the constraints imposed by their financial structure and the competitive environment.
The different approaches within Post Keynesian economics are not mutually exclusive, and many economists combine elements of several. The most common combination is the Kaleckian-Minskyan synthesis, which uses Kalecki’s theory of effective demand to determine the level of output and Minsky’s theory of financial fragility to explain its dynamics. This synthesis has been the basis for much of the empirical work in Post Keynesian economics, including the analysis of the 2008 financial crisis.
The main tension within the field is between the Sraffians and the fundamentalist Keynesians. Sraffians argue that the long-period method is essential for understanding capitalism, while fundamentalist Keynesians argue that the long period is a fiction because the economy is never in equilibrium. This debate has been ongoing since the 1970s and has never been resolved. It reflects a deeper disagreement about the nature of economics itself: whether it is a science of equilibrium or a science of historical process.
A second tension concerns the relationship between Post Keynesian economics and other heterodox traditions, particularly Marxism. Some Post Keynesians, especially those in the Kaleckian tradition, see themselves as building on Marx’s insights into the dynamics of capitalism. Others, especially the Sraffians, are critical of Marx’s labour theory of value and see their work as a return to the classical economists before Marx. This disagreement has prevented the formation of a unified heterodox economics, although there have been repeated attempts to build bridges between Post Keynesianism, Marxism, and other traditions such as feminism and ecological economics.
Post Keynesian economics remains a minority position within the economics profession, but it has a significant presence in a number of universities, particularly in the United Kingdom, the United States, Italy, Brazil, and Australia. It is organized through a number of professional associations, including the Post Keynesian Economics Society and the Association for Heterodox Economics, and it has its own journals, such as the Journal of Post Keynesian Economics and the Cambridge Journal of Economics.
The field has been reinvigorated by the 2008 global financial crisis, which many Post Keynesians saw as a vindication of their analysis. Minsky’s financial instability hypothesis, in particular, became a standard reference point in discussions of the crisis, and Post Keynesian economists were called upon to explain the events to a wider public. However, the crisis did not lead to a fundamental reorientation of the economics profession, and Post Keynesianism remains on the margins of mainstream departments.
In recent years, Post Keynesian economics has become increasingly engaged with other heterodox traditions and with the analysis of contemporary problems such as climate change, inequality, and the rise of financialization. The field has also been influenced by the development of stock-flow consistent models, which integrate the real and financial sectors of the economy in a rigorous accounting framework. These models, developed by Wynne Godley and Marc Lavoie, have become a standard tool for Post Keynesian analysis and have been used to analyse a wide range of policy questions, from the effects of austerity to the sustainability of public debt.
The future of Post Keynesian economics is uncertain. On the one hand, the failure of mainstream economics to anticipate or explain the 2008 crisis has created an opening for alternative approaches. On the other hand, the institutional pressures of the academic profession, which reward mathematical formalism and publication in mainstream journals, make it difficult for heterodox economists to thrive. The field is likely to remain a small but persistent presence, offering a critical perspective on the assumptions and conclusions of mainstream economics and a set of tools for understanding the instability and inequality that characterize contemporary capitalism.