Chris Carroll speculates:

RGE - Capitalism and Skepticism: Why does the economy perform so badly under Republican Presidents?

The facts are hard to dispute; indeed, the historical record is now so stark that diehard Republicans are probably starting to wonder if there is a curse.... Democrats have outperformed Republicans by almost any measure of economic achievement (GDP growth per capita, unemployment, inflation, budget deficits).... Thanks to the profligacy of the current administration... average Federal spending as a fraction of GDP... under Republican Presidents now exceeds that under Democrats over the measured period.... The pattern holds up when the span of historical analysis is extended farther back in time... using stock returns to measure economic performance.... (Data are available on my web page, at http://econ.jhu.edu/people/ccarroll/opinion/CapitalismAndSkepticism.)

An economist’s natural inclination is to say that there’s no point in pondering why Republican performance has been so dismal, because the question cannot be answered with the rigor demanded by professional respectability. But as the tenure of George Herbert Hoover Walker Bush shudders to a calamitous close, history seems to require that we try to give an answer.

That answer can’t be found by drilling down (so to speak) into the specific policy proposals of the two parties, which over the years have evolved in ways too arbitrary to permit any meaningful generalization. Nor are there any clearly identifiable differences in doctrine that should translate into a reasonable expectation of better economic performance under one party or the other....

Maybe capitalism works better when its excesses are restrained by skeptics than when true-believers are writing, interpreting, judging, and executing the rules.... Maybe... capitalism works better when it is being held accountable to some external standard.... [F]or better or worse, the defining manifesto of the latter part of the age was Milton Friedman’s Capitalism And Freedom. But that book’s power derived partly from its fierce independence from the orthodoxies of its time.... The book for the new epoch has not been written yet, but I have a proposed title: Capitalism and Skepticism...