Debt to GDP Ratios: Why Not Make the Numerologists Happy?

Numerology is usually held in low regard in intellectual circles. Unfortunately it is front and center in the debate over national economic policy.

Many economists and political leaders tell the public that we have to keep the DEBT to GDP ratio (capitalized to show reverence) below some magical level. Greg Mankiw professes his adherence to the faith in the NYT on Sunday. The reason that either a specific number or a strict focus on debt to GDP ratios is viewed as silly by people who are not n...