The last few lessons raised questions the model alone cannot settle: how fast expectations and wages adjust, how tightly money tracks prices, how much Crowding Out happens. Economists who weigh the evidence differently form schools of thought.
Key idea
Schools of macroeconomic thought agree on much: in the long run, output depends on resources and technology, money is neutral, and sustained high inflation comes from rapid money growth. They differ mainly on how fast wages and prices adjust, and so on how active fiscal and monetary policy should be.
Why it works
Every school uses the same AD–AS logic. The differences come from evidence that is hard to read: economies are complicated, history does not repeat under controlled conditions, and policies arrive with delays. If wages and prices adjust quickly, gaps close on their own and active policy adds little; if they adjust slowly, recessions can drag on and policy can help. Most economists today borrow from several schools.
| School | Key idea | Policy view |
|---|---|---|
| Classical | flexible wages and prices; markets self-correct quickly | little need for active policy |
| Keynesian | sticky wages and prices; demand drives output in the short run | use fiscal (and monetary) policy to fight gaps |
| Monetarist | inflation comes from money growing too fast; policy acts with long, variable lags | steady, predictable money growth (rules) |
| New classical | rational expectations; predictable policy is anticipated | little lasting effect from predictable policy |
| New Keynesian | prices sticky because of menu costs and contracts, built from firms’ choices | monetary policy can steady the economy in the short run |
A worked example
Worked example: Matching a view to a school
"Wages are slow to fall, so a recession can last years; the government should raise spending to restore full employment." Which school?
- The key idea is sticky wages and a role for fiscal policy.
- That is the Keynesian view.
Answer: Keynesian
Worked example: Agreement or debate?
Classify: (a) "Sustained high inflation happens when money grows much faster than output." (b) "Government borrowing crowds out about half as much private investment as it borrows."
- (a) Economists of every school accept this long-run link: broad agreement.
- (b) The size of crowding out depends on conditions and is estimated differently in different studies: still debated.
Answer: (a) agreement; (b) debated
Common mistake
Treating one school as right and the rest as wrong. Economists broadly agree on many points, such as money's neutrality in the long run, and debate others, such as how fast wages adjust and how active policy should be. Check: before you call a view "wrong," ask whether the disagreement is about the logic or about the evidence on speeds and sizes.