Neither are interchangeable, they're just equally bad for global citizens who want to make a better world.

The problem with two parties is that they collect votes based on ideology not actions. Technically three isn't enough to avoid this but in general use it implies many third parties, such that governing is no longer one painful voice pushed on everyone, but a consensus of the governed.

I'm not american but Ron Paul had his own libertarian party back in the days and he was "R" only because he had to chose a camp.

Ron Paul made it pretty clear during nearly its entire life that he was for less state and more individual liberties.

That makes me think that things would have been way different should he have been elected president.