Principles of Macroeconomics / Unit 10 MAC 0918 review, 2 to 3 minutes
Two Horses, One Economy
The idea
The two perspectives are not rivals to be scored; they answer different questions, and the useful skill is knowing which one a question calls for. Keynesian analysis explains recessions and cyclical unemployment, and it explains why a downturn can persist. It has little to say about growth or about the natural rate. Neoclassical analysis explains growth, potential output and the structure of the labour market, and it says the economy returns to potential on its own. It explains short-run swings poorly, and deep prolonged recessions worst of all. Solow's formulation is that at short time scales something Keynesian is a good approximation, while at very long time scales the interesting questions are best studied in a neoclassical framework. The anchor's image is a circus rider standing on two horses, and the point of it is that the rider needs both.
In practice
Worked example: one demand contraction, told twice. Told the Keynesian way, spending falls, the expenditure line drops, equilibrium output settles below potential, unemployment is real and lasting, and the case for acting on demand follows. Told the neoclassical way, the same contraction opens a recessionary gap, unemployment above the natural rate slows wage growth, short-run supply shifts right, and output returns to potential at a lower price level with no policy at all. Both accounts are internally consistent and both use the same diagram. They differ on one quantity, which is how long the middle of the story takes, and the policy disagreement follows entirely from that.
Where people slip
Three cautions. The self-correction sequence is a claim, not an observation, and it has a named challenger: efficiency-wage theory argues firms may deliberately hold wages above the market-clearing level to retain and motivate workers, in which case the wage adjustment that closes a recessionary gap never arrives and the gap becomes permanent rather than temporary. Yellen set that argument out in 1984 and whether efficiency wages operate at this scale remains disputed. Second, the schools were shaped by the episodes they had to explain, and an argument that fits one decade is not thereby general. Third, the profession has not resolved this: surveys find most economists working in the synthesis that treats prices as sticky and demand policy as usable, while most of those same economists also prefer that discretionary fiscal policy be avoided. The course reports that tension rather than smoothing it.
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