Although many physicists have little interest in philosophical arguments about their subject, an analysis of debates about the paradoxes of quantum mechanics shows that their disagreements often depend upon assumptions about the relationship between theories and the real world. Some consider that physics is about building mathematical models which necessarily have limited domains of applicability, while others are searching for a final theory of everything, to which their favourite theory is supposed to be an approximation. We discuss some particular recent (...) debates about quantum theory in which the underlying assumptions are not fully articulated. Introduction Setting the scene The Ghirardi, Rimini and Weber theory Quantum marbles Radioactive decay and isomerism The limits of quantum theory. (shrink)