re: #807 Ojoe
A BIG centrist party could throw both sets of extremists out into the howling political wilderness where they belong.
There needs to be at least three big parties, you cannot have a center with two; with the number two there is no center.
Actually, I think quite the opposite happens. Moderates must belong to one of two parties. They exercise influence over their party to moderate their policies. Imagine a leftist party gaining control with 34% of the vote—happens all the time in Europe. They get to push policy hard to the left. And we all know how easy it is to undo government programs. I think splitting the parties more than two ways favors entrenchment of the left.