It often happens that parties on either side of such debates will seek leverage against their opponents by articulating higher level rules meant to govern metaphysics itself – rules meant to apply, not to the question ‘What is real?’, but instead to the question ‘What methods of argument are rightly applied to the question “What is real?”’ In other words, philosophers sometimes argue not about what is real but about what is the best way to argue about what is real. The goal is often negative: if a philosopher does not believe in the existence of some entity \(X\), he or she may try to show that a philosophical opponent leans on a weak or irrational style of argumentation generally when arguing that \(X\) exists. Occasionally such debates show an intense connection with philosophy of language, since one common way to make a realist argument that \(X\) exists is to say that, for instance, certain sentences cannot be true or false unless entities like \(X\) exist. Under the influence of the articulate twentieth-century American philosopher W. V. O. Quine, this issue – when and whether certain facts about language require us to admit that certain kinds of entities exist – is often referred to as ‘ontological commitment’.