"Philosophers often think all scientists must be scientific realists. If you ask a simple question like "Are electrons real?" the answer will be "Yes". But if your questions are less superficial, for example whether some well-known scientist was a good scientist. Then, they had insisted that only empirical criteria matter and that they actually did not believe in the reality of sub-atomic entities. Ask "If that turned out to be true, would you still say they were good scientists?" The answer would reveal something about how they themselves understood what it is to be a scientist."