The next rule that needs to be debunked is that Republican candidates must pass a litmus test on cultural issues, especially abortion. This was true in 1988, 1996 and 2000, when religious conservatives were a newly energized political force and one stirred to action by Bill Clinton's misconduct.
But Sept. 11 changed a lot of things, including this old rule. A pro-choice stand on abortion didn't prevent Rudy Giuliani from leading Republican polls until November 2007, when his appointee as police commissioner Bernard Kerik was indicted. And going to all 99 counties swearing he was a right-to-lifer didn't save Mitt Romney in the majority-religious conservative Iowa caucuses in January 2008.
The financial crisis and protracted recession have once again changed the focus of Republican voters. Polls have showed that tea party activists, who number in the hundreds of thousands, tend to be cultural conservatives, but they moved into politics to oppose the stimulus package and Obamacare, not abortion and same-sex marriage.
The third rule that may not be applicable this time is that you have to start early to win. Tell that to Bill Clinton, who announced his candidacy in October 1991, just four months before the Iowa caucuses. Many potential and putative Republican candidates this time seem to be biding their time. You may be able to ramp up a campaign pretty quickly in the Facebook era.
The presidential nominating process is a zero-sum game in which all but one of the competitors must lose. In looking over the possible field of candidates, it's not hard to come up with a reason why each of them cannot possibly win. But it is also a feature of zero-sum games that one player must win. But it's too early to say who yet.