Post-Keynesian Economics

Recovering the Radical Keynes

The label “post-Keynesian” emerged in the decades after World War II to identify a group of economists who believed that the mainstream interpretation of Keynes — the IS-LM model of John Hicks, the neoclassical synthesis of Paul Samuelson — had stripped Keynes’s General Theory of its most important and disruptive ideas. Where the synthesis treated Keynesian economics as a special case applicable mainly to short-run recessions caused by sticky wages and prices, the post-Keynesians argued that Keynes had offered a fundamentally different vision of how capitalist economies work: one in which uncertainty is irreducible, money is never neutral, and full employment is not the natural resting state of a market economy.

Post-Keynesian economics is not a monolithic school. It encompasses several overlapping strands — the Cambridgians (Joan Robinson, Nicholas Kaldor, Luigi Pasinetti), the Kaleckians, the Sraffians, and the financial instability theorists following Hyman Minsky. What unites them is a shared set of commitments and a shared opposition to the assumptions that underpin both old and new neoclassical economics.

Core Commitments

Fundamental uncertainty. Post-Keynesians distinguish sharply between risk (where probability distributions are known or can be estimated) and genuine uncertainty (where the future is unknowable in any probabilistic sense). Keynes’s own term was “radical uncertainty” — the kind that attends decisions about long-term investment, where the relevant future depends on what other agents will do and what technologies, institutions, and political regimes will prevail decades hence. Under fundamental uncertainty, rational expectations in the mainstream sense are impossible. Economic agents rely instead on conventions, rules of thumb, animal spirits, and the state of confidence — all of which can shift abruptly and without warning.

Effective demand. In the post-Keynesian framework, output and employment are determined by aggregate demand, not by the supply-side factors (technology, factor endowments, preferences) emphasized in neoclassical models. There is no automatic mechanism — flexible wages, flexible interest rates — that reliably brings the economy to full employment. Economies can settle into equilibria with persistent unemployment, and demand deficiency can be a chronic, not merely cyclical, condition.

Endogenous money. Post-Keynesians reject the textbook story in which the central bank controls the money supply and banks lend out deposits. Instead, they argue that money is created endogenously by the banking system: banks make loans first and look for reserves afterward. The central bank sets the interest rate, not the quantity of money. This view, once considered heterodox, has been increasingly acknowledged by central banks themselves — the Bank of England’s 2014 Quarterly Bulletin, for instance, described the money creation process in terms virtually identical to the post-Keynesian account.

Income distribution matters. Where neoclassical economics treats the distribution of income as determined by marginal productivity — each factor receiving the value of its marginal product — post-Keynesians see distribution as shaped by bargaining power, institutional structures, and macroeconomic conditions. The functional distribution of income between wages and profits has direct macroeconomic consequences: since workers tend to spend a larger share of their income than profit recipients, a shift from wages to profits can depress aggregate demand and slow growth.

Key Figures

Michal Kalecki arrived at many of the same conclusions as Keynes independently and, in some respects, earlier. Kalecki’s framework, rooted in Marx and Rosa Luxemburg rather than Marshall, emphasized the role of class conflict in determining distribution and the level of economic activity. His dictum that “workers spend what they get; capitalists get what they spend” captures a core post-Keynesian insight: investment drives profits, not the other way around.

Joan Robinson was one of Keynes’s closest collaborators at Cambridge and became the fiercest critic of the neoclassical theory of capital. Her work, along with that of Piero Sraffa, sparked the Cambridge capital controversies of the 1950s and 1960s — a debate over whether it is logically coherent to treat “capital” as a single aggregate factor of production with a well-defined marginal product. The Cambridge (UK) side argued that it is not: the quantity of capital depends on the rate of profit, which is supposed to be determined by the quantity of capital, creating a circularity that undermines the neoclassical theory of distribution. The Cambridge (US) side, led by Samuelson and Robert Solow, eventually conceded the logical point but argued it was empirically unimportant — a resolution that post-Keynesians have never accepted.

Nicholas Kaldor developed models of demand-led growth in which increasing returns, cumulative causation, and export performance drive divergence between regions and nations. His critique of equilibrium economics — that the real world is characterized by increasing returns, path dependence, and historical time rather than the diminishing returns and logical time of neoclassical models — anticipated many of the themes later taken up by complexity economics.

The Financial Instability Hypothesis

Hyman Minsky is perhaps the post-Keynesian figure whose reputation has risen most dramatically in recent decades. Minsky’s financial instability hypothesis argues that stability itself is destabilizing. During periods of prolonged economic tranquility, firms, banks, and households gradually shift from conservative (“hedge”) financing positions — where income flows cover all debt obligations — to more fragile (“speculative” and eventually “Ponzi”) positions, where they depend on refinancing or asset price appreciation to meet their commitments. When confidence finally breaks, the result is a cascade of forced asset sales, collapsing credit, and deep recession — what is now widely called a “Minsky moment.”

The 2007-2008 global financial crisis brought Minsky’s ideas into mainstream discussion. The pattern he described — long stability breeding overconfidence, rising leverage, and eventual collapse — matched the trajectory of the subprime mortgage boom and bust with striking precision. Minsky had been largely ignored by mainstream macroeconomics during his lifetime; after the crisis, his work became required reading.

How It Differs from New Keynesian Economics

The distinction between post-Keynesian and New Keynesian economics is a frequent source of confusion. New Keynesian economics (Mankiw, Blanchard, Woodford) works within the neoclassical framework: it assumes rational, optimizing agents and adds market imperfections — sticky prices, monopolistic competition, information asymmetries — to generate Keynesian-looking results. The New Keynesian Phillips curve, the Taylor rule, and DSGE models are its characteristic products.

Post-Keynesians regard this approach as missing the point entirely. The problem is not that markets are imperfect versions of a well-functioning ideal, but that the ideal itself is misconceived. Fundamental uncertainty cannot be modeled as a known probability distribution with a friction attached. Money is not a veil that can be added to a real model as an afterthought. And equilibrium, in the sense of a state toward which the economy naturally gravitates, is a misleading metaphor for economies that are historical, path-dependent, and perpetually in motion.

Continuing Relevance

Post-Keynesian economics offers a framework for analyzing problems that mainstream macroeconomics has struggled with: secular stagnation, rising inequality, financial fragility, and the macroeconomic consequences of climate transition. Its emphasis on demand, distribution, money, and uncertainty provides tools that are increasingly difficult to dismiss — even if the mainstream has tended to absorb individual post-Keynesian insights (endogenous money, financial instability) without adopting the broader theoretical framework in which they are embedded.