Romney's Budget Math

It seems that you can't run for President these days without engaging in some very dodgy math. Reagan and George W. Bush were the worst offenders so far, proposing outlandishly fantastic budget scenarios, but honestly Democrats haven't been very rigorous, either. Mitt Romney is setting a high bar for this year's contenders by promising to 1) cut taxes to 17% of GDP; 2) hold spending to 20% of GDP; and 3) balance the budget. Hmmmm. . . . Even holding spending to 20% would be difficult; by comparison, Paul Ryan's budget projects spending of about 22%. And since Romney has promised not to cut a penny from defense spending, that would require cutting all non-defense spending by 34%, including Social Security. I find this unlikely. But to balance the budget without cuts like those, we have to raise taxes a lot.