In fact, one of the main reasons for belief in the existence of mathematical objects—some claim this is the only non-question begging reason (Field 1980)—is given by the indispensable use of mathematics in science. The crucial idea, originally put forward by W. V. Quine, and later articulated, in a different way, by Hilary Putnam, is that ontological commitment should be restricted to just those entities that are indispensable to our best theories of the world (Quine 1960; Putnam 1971; Colyvan 2001a). Mark Colyvan has formulated the argument in the following terms: