It ain’t what you don’t know that gets you into trouble. It’s what you know for sure that just ain’t so.
-- Mark Twain
Do high levels of public debt reduce economic growth? This is an important policy question. A positive answer would imply that, even if effective in the short-run, expansionary fiscal policies that increase the debt-to-GDP ratio may reduce long-run growth, and thus partly (or fully) negate the positive effects of the fiscal stimulus.
Debt and Growth - What Causes What?