To James' earlier points, there's has been only one significant de-leveraging, and that was the drop in national debt between WWII and 1980, when it went from about 110% of GDP to 32% of GDP. Several features characterize this period: 1. GDP growth averaged over 4.3% for the first twenty years of it, (2) incremental tax rates on the wealthiest Americans were 70% or higher, (3) federal budget deficits rarely ran over 2% of GDP (once each in the 50s and 60s, 7 times in the 1970s). The Clinton era reduction in debt from 67% of GDP to 56% of GDP is probably best seen as a temporary interruption to a 30 year increase in debt which coincides with (a) a permanent(?) drop in US economic growth to an average level below 3% since 1980, (b) tax reduction policies and spending increase policies which have led to long term structural deficits over 2% of GDP. The current acute problem is due to both tax revenuye being at a postwar low (15% of GDP compared to historical averages of 18%) and spending being at a historic high (24% of GDP compared to historicoral avg of 20%).
There is no compelling data that supports the notion that reducing tax rates on the wealthy stimulates SUSTAINED economic growth, since when tax rates were their highest (1950-1980) the economy grew the strongest, and growth rates have been weaker (under 3%) ever since the top tax bracket dropped below 70%. Yes, other macroeconomic fators come into play, but that's just the point. In recent years we have had some short term improvements in economic growth during farorable tax regimes (Reagan) but also had a short period of sustained growth during unfavoroable tax policies (CLinton). And our worst recession in 80 years came on the heels of the Bush era tax custs.
So anyone who claims there is convincing evidence for tax cuts favoring growth is not looking at any real historical data.