# Keynesian Economics Keynesian economics is the macroeconomic tradition founded by [[John Maynard Keynes]]'s 1936 book *The General Theory of Employment, Interest and Money*. Its **central claim** is that an economy can settle at less than full employment for extended periods because **aggregate demand** — total spending by households, firms, government, and net exports — can fall short of the spending required to absorb the economy's productive capacity. The classical economists Keynes was rebutting had argued, following Say's Law, that supply creates its own demand and that involuntary unemployment is therefore impossible in equilibrium; Keynes argued that the [[1930s Depression]] was the empirical refutation of that view. The political consequence of the Keynesian framework is that **government has both the legitimacy and the capacity to stabilize the macroeconomy** through countercyclical fiscal policy: deficit spending in recessions, surpluses in booms. After WWII this became consensus across the advanced capitalist economies — what historians call the **postwar Keynesian compromise** that ran from roughly 1945 to the stagflation crisis of 1973–1979. The crisis itself, and the Friedmanite monetarist critique that flowed from it, did not so much refute Keynesianism as send it through a series of revisions: the New Keynesians of the 1980s and the New Neoclassical Synthesis of the 1990s rebuilt the framework on microfoundations more acceptable to mainstream macroeconomics. The 2008 financial crisis and the 2020 pandemic both occasioned **explicit Keynesian responses** (TARP, ARRA, the CARES Act, the European recovery funds) from governments of both the center-left and center-right — a quiet vindication of the framework even where the rhetoric of austerity remained dominant. ## Core mechanisms **The consumption function and the multiplier.** Keynes argued that as income rises, consumption rises but by less than the increase in income — the "marginal propensity to consume" is less than one. This produces the **multiplier**: a unit of new spending circulates through the economy, generating additional rounds of consumption, until it tapers off. A fiscal stimulus of size $X produces total output gains of $X × (1 / (1 - MPC)). The multiplier is empirically debated and depends heavily on economic conditions (it's larger in recessions and at the zero lower bound), but the basic mechanism remains the analytic core of Keynesian fiscal policy. **Liquidity preference and the interest rate.** Keynes rejected the classical theory that the interest rate is determined by the supply and demand for loanable funds. In his framework, the interest rate is determined by the **demand to hold money** (liquidity preference) against the supply of money. This makes monetary policy effective in normal times — central banks can shift the interest rate by changing money supply — but ineffective in a "liquidity trap" where money demand becomes infinitely elastic at low rates and additional money is simply hoarded. The post-2008 zero-lower-bound period revived intense interest in liquidity-trap analysis. **Investment under fundamental uncertainty.** Keynes drew a sharp distinction between **risk** (probabilities can be assigned) and **uncertainty** (probabilities cannot be meaningfully assigned). Investment decisions are made under fundamental uncertainty, driven by entrepreneurs' "animal spirits" — confidence, conventions, mood — as much as by calculation. This is why investment is volatile, why expectations matter, and why government can stabilize the economy by stabilizing expectations. **Sticky wages and prices.** Empirically, wages and prices do not adjust quickly to clear markets, especially downward. Workers will not accept nominal wage cuts; firms preserve nominal prices even as demand falls. Sticky-price assumptions distinguish Keynesian from classical and New Classical macroeconomics and remain the central battleground of contemporary macro theory. ## Historical arc **1936–1945 — Founding and reception.** *The General Theory* arrived during the Depression as an explicit attempt to explain a phenomenon classical economics could not. Its reception was rapid in the U.K. (the Cambridge "Keynesian Circus" — Joan Robinson, Richard Kahn, Roy Harrod — formed around it) and slower but eventually dominant in the U.S. Paul Samuelson's 1948 textbook *Economics* became the central vehicle for transmitting a simplified, mathematized "neoclassical synthesis" Keynesianism to two generations of American economists. **1945–1973 — Postwar consensus.** Keynesian macroeconomics dominated U.S. and U.K. policymaking from the late 1940s through the early 1970s. The Employment Act of 1946 committed the federal government to maintaining "maximum employment, production, and purchasing power." Bretton Woods institutionalized international monetary cooperation along Keynesian lines. The Kennedy-Johnson tax cut of 1964 was sold explicitly as Keynesian demand stimulus. By 1971, [[Richard Nixon]] could say "I am now a Keynesian in economics" without political cost. **1970s stagflation crisis.** The simultaneous appearance of high inflation and high unemployment in the 1970s appeared to refute the Phillips curve relationship that simplified Keynesian models had relied upon. Milton Friedman and Edmund Phelps had predicted this in the late 1960s with the **expectations-augmented Phillips curve**: when inflation is anticipated, the trade-off disappears. Friedman's monetarist counter-revolution and Robert Lucas's New Classical critique of the existing Keynesian models produced a serious crisis in Keynesian macroeconomics that lasted into the 1980s. **1980s–1990s — New Keynesian renewal.** The New Keynesians (Mankiw, Romer, Akerlof, Yellen, Stiglitz) rebuilt the Keynesian framework on **microfoundations** — explicit models of why prices and wages might be sticky from the optimizing behavior of firms and workers (menu costs, efficiency wages, asymmetric information, coordination failures). By the late 1990s a "New Neoclassical Synthesis" had produced workable models that embedded Keynesian sticky-price short-run dynamics in a Real Business Cycle long-run framework. This is the standard macro framework taught in graduate programs today. **2008–present — Post-crisis revival.** The 2008 financial crisis produced the largest fiscal stimulus actions in U.S. history (TARP, ARRA) and prompted explicit revisitations of Keynesian liquidity-trap and multiplier analysis (Krugman, DeLong, Summers). The 2020 pandemic prompted even larger interventions (CARES Act, ARP) on what was effectively Keynesian logic. The post-2021 inflation episode is now reopening the older debates about whether large fiscal stimuli during demand-led recoveries are inflationary, with no consensus yet established. ## Foundational works - *The General Theory of Employment, Interest and Money* (Keynes, 1936) — the founding text. - *A Treatise on Money* (Keynes, 1930) — Keynes's pre-General-Theory monetary economics. - *The Economics of Imperfect Competition* (Joan Robinson, 1933) — adjacent contribution that supplied microfoundations for Keynesian sticky-price assumptions. - *Value and Capital* (John Hicks, 1939) and "Mr. Keynes and the 'Classics'" (1937) — the IS-LM framework that became the textbook Keynesianism most economists actually learned. - *Economics* (Paul Samuelson, 1948 onward) — the textbook that transmitted neoclassical-synthesis Keynesianism to postwar American economics. - *The Affluent Society* (J.K. Galbraith, 1958) — popularization of postwar Keynesian political economy. - *Stabilizing an Unstable Economy* (Hyman Minsky, 1986) — post-Keynesian financial-instability hypothesis, prescient about 2008. ## Key thinkers [[John Maynard Keynes]] is the founder. Major postwar developers include **Paul Samuelson** (the synthesis textbook), **John Hicks** (IS-LM), **Joan Robinson** (post-Keynesian, imperfect competition), **James Tobin** (portfolio theory, monetary economics), **Franco Modigliani**, **Lawrence Klein** (macroeconometric modeling), and **[[John Kenneth Galbraith]]** (institutional Keynesianism). The New Keynesian generation includes **N. Gregory Mankiw**, **David Romer**, **[[George Akerlof]]**, **Janet Yellen**, **[[Joseph Stiglitz]]**, **Olivier Blanchard**, and **Greg Mankiw**. Post-Keynesian descendants include **Hyman Minsky** (financial instability) and contemporary figures like **[[Paul Krugman]]**, **Brad DeLong**, and **Larry Summers** in the policy-oriented mainstream Keynesian wing. ## Right-wing relevance Keynesian economics is the **negative pole** around which much of the modern American conservative economic project organizes. The intellectual project of the Mont Pelerin Society ([[Friedrich Hayek]], [[Milton Friedman]], [[James M. Buchanan]]), the [[Powell Memo]]'s call for corporate political mobilization, Friedman's monetarist counter-revolution, the supply-side movement's critique of demand management, and [[James Buchanan]]'s public-choice critique of "fiscal illusion" and politicians' self-interest all define themselves explicitly against Keynesian premises. When [[Ronald Reagan]] declared at his 1981 inauguration that "government is not the solution to our problem; government is the problem," he was repudiating Keynes's foundational claim that government can and should solve macroeconomic problems. Specific right-wing critiques of Keynesianism include: - **The monetarist critique.** Friedman argued that the Keynesian focus on fiscal policy understated the importance of monetary aggregates and that activist countercyclical policy is destabilizing because of long and variable lags. - **The New Classical critique.** Robert Lucas, Thomas Sargent, and others argued that Keynesian models assumed irrational expectations and that rational agents would offset countercyclical policy interventions. - **The Austrian critique.** [[Friedrich Hayek]] argued that Keynesian aggregation obscures the structural distortions caused by easy money and that countercyclical stimulus prolongs malinvestment. - **The public-choice critique.** [[James M. Buchanan]] argued that the Keynesian licensing of deficit spending generates a permanent **political bias toward deficit finance** because politicians face asymmetric incentives — gain from spending, lose from taxing. - **The supply-side critique.** The supply-side movement rejected demand-management as the relevant policy lever and reasserted classical concerns with the marginal incentives that govern production. The interesting empirical fact is that despite this thorough rhetorical repudiation, Republican administrations have **routinely run Keynesian fiscal policy in practice** — large tax cuts financed by deficits during recessions or recoveries (Reagan 1981, Bush 2001, Trump 2017, Trump 2025) function as demand stimulus regardless of the supply-side rhetoric. [[Dick Cheney]]'s reported remark that "Reagan proved deficits don't matter" is the Republican recognition that the political bias Buchanan warned about is real but operates in *both* directions: politicians on the right also gain from deficit spending when it takes the form of tax cuts. ## Critiques and successor schools The mainstream successors to original Keynesianism are the **neoclassical synthesis** (Samuelson, Hicks), **New Keynesians** (Mankiw, Romer, Akerlof, Stiglitz), and the **post-Keynesians** (Joan Robinson, Hyman Minsky, the Cambridge school). The serious contemporary heterodox critique of mainstream macro — the **Modern Monetary Theory** (MMT) movement (Wray, Kelton, Mosler) — is often framed as post-Keynesian even though many post-Keynesians do not endorse the full MMT framework. Right-coded successor schools include **monetarism** (Friedman), the **New Classical** macroeconomics of Robert Lucas, and Real Business Cycle theory. ## Related mental models Keynesian economics is the framework against which most postwar conservative economic thinking has defined itself, and many entries in [[Mental Models]] reflect Keynesian or Keynesian-adjacent contributions: - [[Inflation]] — Keynesian frameworks treat inflation as multi-causal (demand-pull, cost-push, built-in) rather than purely monetary; supports active-management approach - [[Negative Interest Rates]] — Keynesian liquidity-trap analysis is the framework that legitimized the experiment with sub-zero policy rates - [[Bounded Rationality]] — Keynes' "animal spirits" anticipated the bounded-rationality literature; Keynesians have generally been more comfortable than Chicago-school economists with non-rational decision-making - [[Adverse Selection]] — Akerlof and Stiglitz (Keynesian-adjacent) developed the formal framework - [[Moral Hazard]] — Keynesian welfare-economics tradition takes moral-hazard seriously without treating it as decisive against intervention - [[Tragedy of the Commons]] — Keynesian-adjacent justification for collective management - [[Risk]] — Keynes distinguished risk from uncertainty (later operationalized by Knight); the distinction is more salient in Keynesian than Chicago analysis - [[Counterfactuals]] — Keynesian fiscal-stimulus arguments depend heavily on counterfactual reasoning ("without the stimulus, output would have been lower") - [[Wisdom of Crowds]] — Keynes was famously skeptical of market wisdom, anticipating later behavioral-finance critiques ## See also - [[John Maynard Keynes]] — founder - [[The General Theory of Employment, Interest and Money]] — founding text - [[Reagan Tax Cuts]] — repudiation of Keynesian demand management at the level of rhetoric, while reverting to deficit finance in practice - [[Trickle-Down Economics]] — the moral-political framing of the supply-side rejection of Keynesianism - [[Austrian School]] — the school's main right-coded critic on theoretical grounds - [[Chicago School]] — the school's main right-coded critic on monetary-policy grounds - [[Supply-Side Economics]] — the school's main right-coded critic on incentive grounds - [[Economics]] — discipline hub