It's important to argue about how to argue

I don't know specifically what Jon Stewart's "rally to restore sanity" was arguing in favor of, but still I think it was a great idea. The common complaint about it is that it wasn't really "about anything" because it wasn't arguing (at least not overtly) in favor of or against any specific ideological position or policy measure. I find it astonishing how easily people think that if an argument isn't about substance, it must be about nothing at all. There's also this thing called methodology. In order to have a rational discussion, all participants need to work out a set of methodological principles they all agree on. That is, they need to agree on universal principles of how to judge the truth/falsity/plausibility of statements (and, perhaps more importantly, how not to judge them). For example, unless every single participant of a debate agrees that modus ponens is a valid mode of inference and that affirming the consequent is not, all arguments made in the subsequent debate are useless and the debate itself is just a waste of time.

This is why Stewart's initiative is valuable: it may help some people recognize the fact that methodology exists and is important. I don't care what methodological principles he's arguing for; even if I thought they were completely ridiculous, I'd still applaud him, because no one else seems to think methodology matters at all (except for academics, of course, but who cares about them).

But then again, a plea for rationality in political debate is ultimately doomed. The purpose of discussing politics is not truth-seeking but signaling group loyalties. That's why so many people who are passionate about politics are so surprised to learn that something like methodology even exists. If what you're doing is signaling, methodology doesn't matter: you're not arguing because you think what you believe is true and you want other people to see it, but to show your fellow tribe members how committed you are to your tribe's values.