Whether you are a Republican or a Democrat, you probably don't like it when people say nasty things about your party.

But there's an electoral bloc both parties feel free to vilify: those citizens who refuse to vote. They are derided as stupid, lazy or hapless.

Many Americans have figured out that there are problems with the way they vote. The presidential election is a pretty tight contest, so the final tally is expected to be close. But, as anyone who's heard of the Electoral College already knows, U.S. presidents aren't elected on the basis of the popular vote. (Remember Florida in 2000?)

And then there's the controversy over registration. Republicans, warning against vote fraud, have introduced laws across the country that raise the bar for voter registration. Critics of these efforts accuse the Republicans of trying to suppress the turnout of groups that are more likely to vote for Democrats.

What I don't understand is why no one is addressing the elephant in the room: the fact that 40 percent of Americans of voting age don't see any reason to cast their ballots at all.

In national election after national election, eligible voters who choose to refrain from voting make up what some political scientists have called a "silent plurality." There have been moments when that plurality was close to a majority. In 1996, more than 49 percent of the voting age population declined to vote. In 2008, turnout of eligible voters went up to nearly 62 percent - the highest since 1968. But the number of those who refused to vote was still larger than those who voted for Barack Obama, the winning candidate. Nonvoters, in short, make up the biggest electoral bloc in the nation.

Withholding one's vote in a presidential election is, in fact, a rational response to the existing political order. The Electoral College is a big part of the problem. If you live in persistently Republican Texas, you have good reasons to doubt that your vote for Obama will influence the outcome. If you live in solidly liberal Massachusetts, casting a vote for Mitt Romney as president is likely to have little effect.

Pundits say that there are only nine "battleground" states that really matter in this year's presidential election. But modern campaigns have the data to target even more narrowly than that, and are focusing on just 106 "swing counties" (out of 3,143 in the United States).

The reason is the winner-take-all system of the Electoral College, which dictates that whoever wins a majority of the votes in a state gets all of that state's electors. This sort of mechanism tends to foster the creation of two-party systems. (The framers of the Constitution actually didn't want to have political parties at all.)

The problem is that a two-party system doesn't come anywhere close to exhausting the range of options for political expression. That's why it's wrong to dismiss nonvoters as ignorant couch potatoes. Under the American system, a vote cast for a third party (the Libertarians, say, or the Greens) is a lost vote. Your ballot has no effect whatsoever on the actual balance of power. So abstaining from an election that offers you no chance to pick the policies you'd like to see makes perfect sense.

By contrast, systems based on proportional representation offer much more precise opportunities for the expression of political preferences. If you're a German, for example, you can cast a vote for the Free Democratic Party or the Greens, knowing that one of these relatively marginal parties might very well end up forming a coalition with the more popular Christian Democrats or Social Democrats and thus influencing the formation of the government. It should come as no surprise that participation in German elections tends to be higher than in the U.S. (The world champions, perhaps, are the Swedes, who vote at a rate of about 80 percent of the voting age population.)

Proportional representation has many problems, of course - most notoriously, fragmentation and chronic instability. And, to be fair, voter participation is trending downward in just about every established democracy.

Yet almost every country that has achieved democracy over the past 30 years has adopted a parliamentary system based on proportional representation, an approach closer to the German model than the American one. It's easy to imagine why. People who have obtained the cherished right to choose their leaders want to think their votes actually count. Like it or not, the institutions of American democracy aren't a model for the rest of the world anymore.

Can Americans change their system to make it more democratic? Two states, Maine and Nebraska, apply proportional principles to the presidential election: Electors from these states are awarded in proportion to the number of votes cast for each candidate. There's also talk of getting rid of the Electoral College altogether and allowing direct election of the president by popular vote. But can anyone really expect the two currently existing parties to agree?

One thing is clear: Half of the American population doesn't feel represented by the current system, and this disaffection appears to be deepening with time. Meanwhile, the ranks of the abstainers continue to swell. Call me crazy, but this doesn't seem to bode well for the future of democracy in the United States.

Christian Caryl is a senior fellow at the Legatum Institute, a contributing editor at Foreign Policy, and a senior fellow at the MIT Center for International Studies.