We haven't even made it to the New Hampshire primary, but millions of Americans are already sick of hearing about the 2008 race. Bad as the torrent of news is, I find the repetition of myths about voters and voting even more galling. Whether you're arguing with friends or watching the news, you hear many claims about how American democracy works that just aren't true.

1. People vote their self-interest.

In fact, there is only the tiniest correlation between income and party. The country is not divided into two camps: the poor, who vote Democrat, and the rich, who vote Republican. If you consider your own experiences, this is hardly surprising: Are your rich friends really Republicans and your poor friends Democrats?

Self-interest is also a bad predictor of views about specific issues. Yes, the elderly heavily support Social Security and Medicare, but so does almost everyone else. The old bumper sticker says, "If men could get pregnant, abortion would be a sacrament," but men are actually slightly more pro-choice than women. And so on. Pollsters have found a few exceptions where self-interest really matters, such as smoking restrictions, which smokers obviously tend to oppose. But overall, where voters stand has little to do with where they sit.

2. Unselfish voting will solve our problems.

We often blame political problems on the selfishness of our fellow citizens. If people would just sacrifice their own interests for the country's good, our problems would be solved, right?

Hardly. Selfishness is not the only cause of political strife. The U.S. electorate is bitterly divided by ideology and religion, and that's what makes our political disagreements so intractable. After all, if voters were truly selfish, they would negotiate amicable settlements and take what they could get, instead of zealously fighting the same battles year after year.

Even if the American public put aside ideological and religious differences, unselfish voting could easily be dangerous. If people are mistaken about how to make society better off, their good intentions will produce bad consequences. A selfless doctor who believes that leeches will cure cancer is dangerous. So is a selfless voter who truly believes that high tariffs will cure unemployment.

3. Voters' errors balance out.

It's fashionable to dismiss worries about the mistakes of the average voter by praising "the wisdom of crowds," to use James Surowiecki's phrase. Sure, the average voter knows little about politics, economics and policy. But for every voter who overestimates the benefits of tariffs, carbon taxes and the Iraq war, doesn't another make the opposite mistake?

Actually, no. Voters are frequently wrong in the same way. This is particularly clear in economics. If you've never studied economics, you're not equally likely to oversell or downplay the benefits of free trade. Instead, people who know nothing about economics are staunch protectionists, and people who know a lot of economics are avid free-traders.

The fact that voters' errors fail to cancel out seems strange. Why would people have strong opinions about a subject they've never studied? The simple answer is that a lot of voters are irrational, and it shows. In politics and economics, people believe what makes them feel good, even if the evidence is against them. For most Americans, it feels a lot better to scapegoat Mexicans or Chinese for the country's economic woes than it does to calmly examine the facts.