While fortifying myself for a long election night, I happened upon a very interesting piece by Jon Chait about the dynamics of election predictions, and particularly the tendency of conservatives to guess very high about Republican gains while progressives tend to be pretty objective. Here’s the key passage:

I think there’s a strange sociology at work here. Obviously, there has been a strong Republican undertow in Washington over the last year or more. The primary effect of this undertow has of course been to improve the GOP’s prospects. But the secondary effect has been to make conservatives giddy and liberals depressed. On the right, a can-you-top-this sensibility is at work in predicting the November bounty. And while there are many conservatives making outlandishly hopeful electoral predictions, and very few liberals doing the same. Nate Silver is, properly, the lodestar of liberal electoral analysis, and his prediction is admirably down-the-line. Not even partisans like Markos Moulitsas are challenging his median prediction of a 53-seat House loss.
And so, in a lopsided environment like this, it seems like all the social pressure is pushing pundits toward Republican-friendly positions. That’s why you see them making nonsensical guesses where they throw out a reasonable number (like 60-some seats in the House) along with a caveat that the number could be vastly higher. What does this show? It shows they’re afraid of guessing low but not afraid of guessing high. Nobody wants to be on the wrong side of this wave. Nobody wants to be the mainstream reporter who is ridiculed by Republicans for not getting it.

There’s an amusing example of this phenomenon in the Weekly Standard this morning, where Jay Cost, a very smart guy who knows how to run numbers, ties himself into knots trying to justify a prediction of very large GOP gains. He even suggests that he’s bravely breaking away from the “herd” that is aiming lower, when (whether he’s right or wrong) he’s pretty clearly following his conservative buddies who are treating this election as an Epoch-Defining Event instead of a bad-economy midterm dominated by Rebublican-trending older white voters who are in part just lopping off the low-hanging fruit grown by previous Democratic landslides. In his enthusiasm, Jay winds up predicting things that don’t look that credible from available evidence, like a very competitive California Senate race and (I really hope he’s wrong about this) a gubernatorial win for Tom Tancredo.
Now some progressives look at this phenomenon, which extends far beyond election predictions into all forms of political expression, and argue that Democrats are giving up something valuable by trying to be objective, instead of countering conservative exaggerations and spin with their own. I understand the argument, but don’t buy it. For every advantage conservatives gain by hype, they lose something intangible but important in the long run: the ability to resist believing in their hype.
I think it’s very likely we’ll see this downside of “enthusiasm” in abundance after this election, when Republicans convince themselves they’ve won a mandate to undo all of the Obama administration’s policies and set the country on a rightward course that would have alarmed Ronald Reagan. Indeed, many Republicans are visibly buying into the ancient, threadbare conservative argument that the path to future electoral victories, in 2012 and beyond, is to move as far to the right as the hard-core party base (known lately as the Tea Party Movement) wants it to. So when they emerge from their victory parties fired up to repeal even the popular elements of ObamaCare, or to champion more high-end tax cuts, or to gut regulation of Wall Street, or to abolish the Departments of Education and Energy, or to immediately balance the federal budget (which means gigantic changes in Social Security and Medicare), they may not realize they’ve over-interpreted this election to their peril. I’d just as soon my party be less enthusiastic, and more in touch with reality.