Language, proof and logic

What do the fields of astronomy, economics, finance, law, mathematics, medicine, physics, and sociology have in common? Not much in the way of subject matter, that's for sure. And not all that much in the way of methodology. What they do have in common, with each other and with many other ¯elds, is their dependence on a certain standard of rationality. In each of these ¯elds, it is assum…