Ezra Klein/Center on Budget and Policy Priority dataThere’s talk that the McCaskill-Corker spending cap will be the cost of raising the debt ceiling. This would be, to put it simply, completely insane. Spending caps are bad policy, and the McCaskill-Corker spending cap — which holds spending to 21.5 percent of GDP, or three percentage points lower than it is right now — is a badly designed spending cap.