The impulse for harmony in politics is understandable. All else being equal, most of us would prefer civility to narrow-minded partisanship and petty bickering. The difficulty is, of course, that all else is not equal. Most of us would accept partisanship and bickering if it meant the enactment of better policy.

This is the problem with facile appeals to comity and non-partisanship. When people innocently ask why the parties can’t get along, there is often a veiled assumption: The other side needs to stop dragging their feet and get with the program — our program. They would be perfectly willing to …