Decius wrote:
...the electoral college eliminates the impact of minority parties in presidential elections. Broad but shallow support accounts for nothing.

Furthermore, you almost never see third party candidates in debates. The system is really ruled by money. Unless they are backed with huge financial resources they cannot get access, because access is purchased through advertising.

...on the Senate and House, you have positions that go to minority and majority parties... its all setup with the assumption that there are only two. The few independents that manage to make it into the place don't have the systemic support networks of either party to help them actually get laws passed...

I can't disagree with any of those points, but I do think the landscape (if not voters' attitudes) has changed a bit. Up through the 1980s (before cable TV, talk radio, and the Internet), I think it was easier for the establishment to maintain the status quo. In 2008, the systemic barriers to other contenders that you mentioned aren't quite as effective as they once were, but I agree that they do still exist (the exclusive debates bother me the most). I suppose it boils down to a chicken vs. egg discussion about whether the culture is responsible for the system or vice versa. Perhaps they're constantly feeding off of each other, but I still see it as being primarily cultural.

Either way, voters in 2008 have no excuses for not being aware of all available options, assuming they're inclined to do a little homework. Collectively, we have the power to force change (I'm speaking politically, not ideologically), but I don't think that's what most voters want. Most want something familiar, and they find it in the two-party elections with which they've grown up. Even those who do consider alternatives often wind up voting for one of the two major parties, pursuant to Duverger's Law, which actually supports your argument more than mine.

RE: Against Independent Voters - Stanley Fish - Think Again - Opinion - New York Times Blog