6:53 PM PT: So it's over. I don't have any brilliant insight, but I stand by what I said before, which is that I think this debate will mostly be forgotten -- except the portion about Social Security, in which Mitt Romney said that Rick Perry wanted to get rid of the system, and Rick Perry didn't disagree. That's a core difference: Romney said Social Security basically works, and Rick Perry said it's a Ponzi scheme that must be stopped. Romney will argue that Perry's position is bad politics; the question is whether Republican voters give a damn.