...from in a book review by Brad DeLong:
Benjamin M. Friedman ... makes a powerful argument that—politically and sociologically—modern society is a bicycle, with economic growth being the forward momentum that keeps the wheels spinning. As long as the wheels of a bicycle are spinning rapidly, it is a very stable vehicle indeed. But, he argues, when the wheels stop—even as the result of economic stagnation, rather than a downturn or a depression—political democracy, individual liberty, and social tolerance are then greatly at risk even in countries where the absolute level of material prosperity remains high.
Consider just one of his examples—a calculation he picks up from his colleague Alberto Alesina, Ropes professor of political economy, and others: in an average country in the late twentieth century, real per capita income is falling by 1.4 percent in the year in which a military coup occurs; it is rising by 1.4 percent in the year in which there is a legitimate constitutional transfer of political power; and it is rising by 2.7 percent in the year in which no major transfer of political power takes place. If you want all kinds of non-economic good things, Friedman says—like openness of opportunity, tolerance, economic and social mobility, fairness, and democracy—rapid economic growth makes it much, much easier to get them; and economic stagnation makes getting and maintaining them nearly impossible....Where growth is rapid, the movement toward democracy is easier and societies become freer and more tolerant. And societies that are free and more tolerant (albeit not necessarily democratic) find it easier to attain rapid economic growth.
It is therefore not surprising that growth under Republicans is consistently lower than growth under Democrats (See, for example, Kevin Drum
. There is a fascinating graph showing that the top 5% actually don't do better under Republicans than Democrats-- but they do keep everyone else poorer. Vital if you're main goal in life is keeping other people down.)