The part, unfortunately, that we need to use in order to make knowledge about the rest of it. Sokal may be a finer joker, but deciding whether a statement is a joke or not depends on the listener, not the speaker. Which would get a good laugh from anyone who studies domestic violence, soil erosion or suicide. Science, after all, is a social construction. I don't mean that as some tricky language thing, I mean it as an observable fact.
Science is made by people, commonly working in groups.
It is social. It is put together according to certain principles. It is a construction. Because its the best social construction anyone has devised for testing theories about the world, showing their limits, and coming up with better ones. Unless one wants to treat it as a religion and worship scientists as priests, surely any thinking person has a right to ask.