The Synthesis That Never Happened

When I was 21, I decided that I would devote my life to reconciling micro and macro-economic theory.
Then I came down with Chronic Fatigue Syndrome, spent six years in bed, and became a blogger instead.
Economics’ loss is Judaism’s gain.
Micro and macro do not square. The gap has a name, the microfoundations problem, and it has persisted since Keynes without resolution.
Micro assumes rational agents maximizing utility under constraints. Markets clear. Prices adjust. The supply curve meets the demand curve and the story ends. Macro looks at aggregates such as GDP, unemployment, inflation, and the price level. It finds patterns that micro cannot generate by simple addition.
The Sonnenschein-Mantel-Debreu theorem proved this in the 1970s. You cannot aggregate individual demand curves into a well-behaved aggregate demand curve, even when every individual demand curve behaves perfectly. Aggregate demand can take almost any shape. The translation from micro to macro is not mathematically clean. It might not be possible at all.
Keynes saw the problem decades earlier and named it the fallacy of composition. If one household saves more, its wealth rises. If every household saves more at once, aggregate demand falls, income falls, and total savings might drop. Individually rational choices produce collectively irrational outcomes. The paradox of thrift.
The labor market shows the same gap. Micro says if wages sit above market-clearing levels, unemployment emerges and wages fall until the market clears. Macro observes persistent involuntary unemployment across decades and across economies. Wages do not adjust downward the way the micro story requires.
Robert Lucas pushed back in 1976. He argued that macro models built on historical patterns break down when policy changes, because people adjust their expectations. He and his students demanded microfoundations, meaning macro models built from optimizing agents.
The response became DSGE modeling: dynamic stochastic general equilibrium with a representative agent. But the representative agent dodges the aggregation problem rather than solving it. You assume one agent stands in for the economy and the problem disappears by fiat. Heterogeneity, credit, bankruptcy, and the institutional structure of finance all get flattened.
2008 exposed the cost. Mainstream DSGE models missed the financial crisis because they had no banking sector worth the name, no role for private debt, and no way to model cascading failures. The micro foundations looked tidy and the macro predictions came out wrong.
The implications run through the discipline and out into public life.
Policy debates cannot be settled by theory. Austerity versus stimulus. Tight money versus easy money. Free trade versus industrial policy. These fights persist because the micro and macro answers diverge and no synthesis adjudicates between them. Economists sort by priors. The math decorates the priors.
Prediction fails at turning points. Micro-grounded macro handles small perturbations around equilibrium. It does not handle regime changes, bubbles, panics, or structural shifts. The 2008 crisis, the 2020 pandemic response, and the post-2021 inflation spike each caught the profession flat-footed.
Heterodox schools get rehabilitated after each failure. Post-Keynesians, Austrians, Minsky followers, and Modern Monetary Theory proponents all argue the synthesis fails. They disagree among themselves. But the mainstream cannot dismiss them the way it once did, because the orthodox tools keep missing things.
The profession sustains itself through coalition maintenance more than through predictive success. Peer review, credentialing, journal hierarchies, and policy consulting networks reward technical sophistication within accepted frameworks. Economists who point to the microfoundations gap drift toward heterodox journals and lose career capital. The incentive structure protects the synthesis even when its failures show.
Money sits at the deepest layer of the problem. Micro cannot explain why money exists or why it has value. Macro needs money and uses it every day. The standard trick introduces money exogenously as a modeling device. The origin and role of money, its relationship to credit, banking, state power, and trust, sits outside the theory.
For the working economist this might not matter day to day. For the citizen trying to understand why economic predictions fail and why policy debates never end, the gap explains a lot.