At the Right Coast, University of San Diego law professor Tom Smith asks an interesting question. Why do partisans overstate their party’s chance of winning an election? After all, as Smith notes, doing so may lead to complacency:
A question — take a biased media outlet, for example NPR, which I listen to a lot. It consistently overstates how well things are going for O[bama] and the Dem Party. I don’t listen to Fox so much but assume they do they same thing for the GOP. Why? How does this help the party they are biased in favor of? Doesn’t it promote complacency? How does having a falsely positive view of things help the side for which you are skewed positive? On Wisconsin, panic did set in, but really late, like the day before the vote. Wouldn’t panic have been useful earlier? This suggests to me that (perhaps) the bias is more unconscious than an attempt to be useful to the side favored.
Unconscious bias may be a part of the story. But this kind of overclaiming isn’t limited to media pundits. Campaign operatives do the exact same thing, including even skilled political strategists who follow the polls closely and probably know very well what their candidates’ true chances are. The real answer to Smith’s question probably has to do with the “bandwagon effect.” A small but significant number of swing voters tend to support whichever side seems to be winning, partly because they want to be identified with a winner and partly because of a sense that whoever seems to be winning might well be the best person for the job for that very reason. Bandwagon voters are unlikely to make a decisive difference in an election where one side has an overwhelming edge to begin with. But they can be decisive in a closer race. They can also increase the winner’s margin of victory, thereby adding to the perceived extent of his “mandate.” For these reasons, candidates and their supporters routinely project greater optimism than they really feel.
The bandwagon effect is an inversion of the normative ideal of democracy. Instead of choosing the winner based on their perception of what would best serve the public interest, bandwagon voters modify their perception of the public interest based on who they think is likely to win. Worse, these voters are often among the key swing voters who decide electoral outcomes.
Obviously, few well-informed voters with well-developed views on the issues are likely to change their vote based on bandwagon considerations. But rational political ignorance is extremely widespread, and is especially common among swing voters.