A growing body of evidence suggests that uncertainty is counter cyclical, rising sharply in recessions and falling in booms. But what is the causal relationship between uncertainty and growth? To identify this we construct cross country panel data on stock market levels and volatility as proxies...

There appears to be a strong upward drift in policy-related economic uncertainty after 1960. We consider two classes of explanations for this rise. The first stresses growth in government spending, taxes, and regulation. A second stresses increased political polarization and its implications for...