America’s shrinking middle class

Considering that I graduated from high school in 1988, the figures described in this article are startling:

http://www.nytimes.com/2013/09/19/business/americas-sinking-middle-class.html?ref=todayspaper&_r=1&

I wonder three things about this phenomenon:

1. To what degree are they the result of politics/government policy?

2. Assuming that you see this as a problem, is there a political solution to it?

3. If this phenomenon was NOT caused by politics, what caused it, and does this cause admit of ANY solution?