In physics general relativity and quantum field theory are applied to different domains and at least one, possibly both, are widely recognized as mere approximations to the ultimate theory that subsumes them.
I'll defer to Dr. Miller on this if he cares to weigh in, or any other professional economist, but my outsider's impression is that in economics as discussed by Romer the situation is more that contradictory theories are being applied to the same domain, without a serious effort to determine experimentally which (if either) is correct.
Hanson once said that testablity is not a useful notion in the social sciences. That seems kind of crazy to me, but I am not an economist.
Another month, another rationality quotes thread. The rules are: