  Premise 3 is far more controversial. Field defends this premise by observing that “the truth-values of our mathematical assertions depend on facts involving platonic entities that reside in a realm outside of space-time” (Field 1989, p. 68) and thus are causally isolated from us even in principle. However, this defense assumes that any adequate explanation of the reliability in question must involve some causal correlation. This has been challenged by a variety of philosophers who have proposed more minimal explanations of the reliability claim. (See Burgess &amp; Rosen 1997, pp. 41–49 and Lewis 1991, pp. 111–112; cf. also Clarke-Doane 2016. See Linnebo 2006 for a  critique.)[13]