[throwawaygal7]

I think there is a pendulum effect, but it's dominated by a leftward cultural trajectory.

The republican party really just takes democrat positions from a few years ago on social issues, adds some murmering about trying to reign in the debt, occasionally cuts taxes , and continues the progression of the dominant culture.

My theory is the increasing polarization is due to one side clearly seeing their dominance in the culture and wanting to crush all opposition; and some reactionaries on the right noticing this state of affairs and calling for more aggressive means to try to change the situation.