There's a perfectly good English term for that, Natural Philosophy. What these people do could perhaps be called "Social Natural Philosophy". But if you don't have the ability to do a controlled experiment, you can't do science (or else the term loses all meaning, e.g. is history a science? There are plenty of historians using rigorous methods (often more rigorous than social science, frankly), and it's certainly a "practice of knowing"; nevertheless we would generally say no).
No. There are many methods beyond the controlled experiment. The natural experiment is one, which is extremely important in epidemiology for example. You don't show smoking is harmful by setting up a control group to smoke incessantly for 30 years. Your view of science is far too narrow.
Your view is far too broad. There are many rigorous (and less rigorous) fields of study that are not sciences; if everything is a science then the term becomes useless. (I'm quite content with saying epidemiology is not a science; it draws from scientific knowledge but involves non-scientific study as well, much like history).
I agree about the controlled experiment aspect, but before we arrive at that stage social description allows us to explore a range of possible theories.
In any case, the language example used here was more to demonstrate the historic and perceptual differences as to what amounts to science, and that for some social science is not necessarily an oxymoron.
Edit: wissenschaft and wetenschap are furthermore direct translations, while natural philopsophy moreso indicates a field or discipline (akin to 'Naturphilosophie' or 'wijsbegeerte'). While this can be regarded as 'just semantics', the categories are subtly different enough, at least to a second-language speaker.
