Explain a few things to me. One: Why did he announce publicly last night that he was “reassessing” if he truly hadn’t decided to quit yet? If you want to push the talking point that Iowa doesn’t mean anything and that the real race begins in South Carolina, then push it. Don’t show everyone that the caucuses have left you so badly shaken that you’re thinking of getting out. And if that was simply a ploy to give him an excuse to skip campaigning in New Hampshire, where he has no shot, then why immediately turn around this morning and announce that you’re back in? (“I was out on the trail when it kind of came to me.”) Lie low for a few days as the New Hampshire scrum gets going and then announce that you’re back in and headed for Carolina. Even some of his advisors are confused about the reversal: “It seemed like everything was going to wind down and life was gonna be good, and now there’s an explosion and I don’t know what’s going on.”

Two: He says in the clip that he’s looking forward to a primary with real Republicans, not the Democratic infiltrators for which Iowa is known. But … South Carolina’s an open primary. If you want to make mischief for a conservative, it’s probably easier to do it there than in Iowa. And even if Iowa’s teeming with independents and liberals, how did that hurt Perry last night? Ron Paul was the big beneficiary of the non-Republican vote and surely will be again in South Carolina. Perry’s problem isn’t squishes lining up to torpedo him, it’s conservatives who have given up on him after one too many goofs. What he’s really saying here, I take it, is that he’s looking forward to a primary of southerners, which is fair enough — but then so is the guy who beat him out for fourth place last night.

Three: How does he win South Carolina? The Times has a theory:

While the campaign spent millions of dollars in Iowa, Mr. Perry may still have enough money to compete effectively in South Carolina, where television is less expensive than in New Hampshire and Florida, and his super PAC will likely provide additional firepower. While Mr. Perry will probably need to reboot his fund-raising to raise enough money to compete strongly in Florida’s primary on Jan. 31, his supporters believe the results in Iowa, however inauspicious for Mr. Perry, showed a hunger among Republicans for a more conservative alternative to Mr. Romney.

“Think how early we are in the process,” said a person with knowledge of the campaign, who asked for anonymity in order to discuss deliberations among Mr. Perry’s aides. “The reality is, not one delegate was committed yesterday. We are still early enough in the process that if the candidate has the drive to go forward, he ought to.”

“If we can get this back to a Perry versus Romney field,” the person said, “Perry can win.”

If he does well there, he’ll burst Santorum’s bubble, finish off Gingrich, and lay to rest whatever remains of Huntsman’s campaign after his likely defeat in New Hampshire. But that all depends on how well Santorum does in NH, of course. If Santorum gets a major bounce from Iowa and finishes a respectable second to Mitt up north, he’ll arrive in South Carolina as the presumptive social-con Not Romney, which makes things very hard for Perry. Perry fans, in fact, are now in the strange position of needing a Romney landslide next Tuesday to prove that Santorum’s a paper tiger whom South Carolinians shouldn’t bother taking a chance on.

And even if that Romney landslide happens, that’s dangerous too. The big rap on Mitt is that he has a low ceiling because most of the party hates him, but once there’s solid proof to the contrary of that in some state, it might shake loose undecideds elsewhere. Plus, Romney will have Nikki Haley campaigning for him in South Carolina, so if he shows up with lots of momentum, lots of endorsements, and a four-way split among the Not Romney vote, I wonder if he ends up winning there and suddenly looks so inevitable that no one can catch him even in a two-way race. That is to say, the assumption all along has been that anyone in the field (except Ron Paul) has a good shot of taking Romney out head to head. But maybe not. Maybe, if Romney runs the table early, the media buzz about inevitability and electability becomes a self-fulfilling prophesy in which even undecideds who prefer Perry or Santorum ideologically choose to opt for the guy with all the money and organization who can beat O. And on top of all that, for Perry to come back in South Carolina would be unprecedented: Since 1980, everyone who won there had also won in either Iowa or New Hampshire. Perry finished a distant fifth in the former and will do similarly in the latter. Are those long odds good enough to justify continuing, knowing that his participation will deepen the split in the conservative vote and inadvertently help Romney?

Next debate is Saturday night, by the way. Yesterday that looked like it was going to be an “everyone against Romney” affair, but with Perry back in and eager to take Santorum down, Mitt now has himself an unlikely ally.