[tpeo]

Do astronomers perform experiments?

This is the example used in methodological discussions of economics. I don't know if astronomers do actually perform experiments on some limited scale, but it seems that classicaly they relied on "luck" to test predictions e. g. testing general relativity through observations of eclipses. In social sciences, there is a somewhat similar thing called "natural experiment", which is the main test for the validity of predictions. In both cases, the researcher takes a more passive role in testing his predictions.

This can be dauting to researchers, but overall it's for the best. There are indeed experiments in economics, specially in game theory. But the majority of possible experiments would cross the boundary of what is morally acceptable, and well into morally abhorrent e. g. randomly restricting a sample's access to education to estimate it's effects on wages.

[marcosdumay]

It helps that astronomy is a branch of physics. In a sense, astronomers do perform experiments, on different conditions but with the same theory. (By the way, that's what bothers me most about cosmology, it seems to not agree with any small scale experiment performed.)

Well, certainly, natural experiments can lead to knowledge. But that's a much slower and more dangerous path, artificial experiments are better in every sense, except that they are mostly not available for economics. Anyway, I don't think the use of natural experiments are the bottleneck currently holding economics back.