 The  Kochen-Specker Theorem,  the earlier theorem of Gleason (Gleason 1957 and Bell 1966), and other no-hidden-variables results, including Bell’s inequality (Bell 1964), show that any hidden-variables formulation of quantum mechanics must be contextual. It must violate the noncontextuality assumption “that measurement of an observable must yield the same value independently of what other measurements may be made simultaneously” (1964, reprinted 1987c: 9). To many physicists and philosophers of science contextuality seems too great a price to pay for the rather modest benefits—largely psychological, so they would say—that hidden variables provide. 