Are debates good for Republicans?

Amy Davidson is unsure:

Debate after debate has included moments that seem disastrous for Republicans, individually and collectively, and yet they all seem to get Fox News immunity totems anyway. That’s what keeps them from functioning as circular firing squads, as much as they might look like them sometimes. And why? After each debate, one wonders whose misstep, or whose continued presence, helped whom, but perhaps that’s the wrong way to look at it. Maybe the Republican campaign against President Obama’s election has come together, whether it was planned that way or not, as an ensemble piece, not a solo show.