The victories of Scott Brown and Christine O’Donnell are the two biggest surprises of the election cycle, to date. What do their two races have in common?

They were both anti-establishment candidates, yes, but I think there’s something a little bit more than that. In Massachusetts, voters were told that they were supposed to vote for Martha Coakley so as to preserve Ted Kennedy’s legacy and ensure that the health care bill was passed. The message to Republican primary voters in Delaware wasn’t quite that explicit, but certainly plenty of people — from Mike Castle’s campaign to some respected (but establishment) conservative voices like Charles Krauthammer — conveyed the impression that they had to vote for Mr. Castle because Ms. O’Donnell was unelectable.

(I happen to think that they were right about that — Ms. O’Donnell has only a one-in-six chance of defeating Democrat Chris Coons, according to our forecasting model.)

But voting is principally an emotional act — and voters don’t like the sense of having been told what to do. They rebelled against it in Massachusetts and they rebelled against in Delaware; sometimes, they may resent it so much that they will go to arguably self-destructive lengths in order to avoid casting the vote that they’re “supposed” to cast.

We also saw this on a number of occasions during the Democratic primaries of 2008: remember how ‘inevitable’ Barack Obama was before New Hampshire? But it’s liable to be much more acute when the unemployment rate has been sitting at 10 percent for a year, and the establishment of both parties is tremendously unpopular. I think we might need a couple of days to digest what this might mean for November.