  This leads Demopoulos and Friedman to conclude that reducing a theory to its Ramsey sentence is equivalent to reducing it to its empirical consequences, and thus that: “Russell's realism collapses into a version of phenomenalism or strict empiricism after all: all theories with the same observational consequences will be equally true” (1985, 635). Similarly, Jane English (1973) argued, though on the basis of different considerations, that any two Ramsey sentences that are incompatible with one another cannot have all their observational consequences in common. Hence it seems that if we treat a theory just as its Ramsey sentence then the notion of theoretical equivalence collapses onto that of empirical equivalence. (Demopoulos 2003 argues that similar considerations show that structural empiricism also collapses truth to empirical adequacy; he also discusses the relationship between Newman's problem and Putnam's Paradox. Votsis 2003 argues that the conclusion of the Newman argument doesn't undermine ESR after all. Gordon Solomon 1989 defends Richard Braithwaite's claim that Eddington's structuralism (see 4.1 below) is vulnerable to Newman's argument.)