How about the 2 parties allow a few other parties in? How can we not be polarized?
Sad as it may sound, most political science professors and historians are in agreement that a federalist republic works best when it is run by people of two distinct political parties.
If you have three or more, then you have no resolute theoretical aisle to cross, no way to have theoretical "middle ground" because it's much more difficult to define what the term
middle ground even entails.
Look at what's been happening in contemporary European states like Greece, for example.
Look at what happened to Yugoslavia after the Berlin Wall fell.
Look at what happened to Germany after WWI.
Those are three good examples of what multiple parties can do to a republic, no matter how strong its federalism may be, and no matter what other issueslike economic inflation and multiculturalismcomplicate the big picture.
In the U.S., the two-party system works best. What sucks IMHO is that we have way too many third parties influencing those who represent them.