 Contemporary discussion commonly focuses on Laudan’s (1981) argument to the effect that the history of science furnishes vast evidence of empirically successful theories that were later rejected; from subsequent perspectives, their unobservable terms were judged not to refer and thus, they cannot not be regarded as true or even approximately true. (If one prefers to define realism in terms of scientific ontology rather than reference and truth, one may rephrase the worry in terms of the mistaken ontologies of past theories from later perspectives.) Responses to this argument generally take one of two forms, the first stemming from the qualifications to realism outlined in  section 1.3,  and the second from the forms of realist selectivity outlined in  section 2.3—both  can be understood as attempts to restrict the inductive basis of the argument in such a way as to foil the pessimistic conclusion. For example, one might contend that if only sufficiently mature and non-ad hoc theories are considered, the number whose central terms did not refer and/or that cannot be regarded as approximately true is dramatically reduced (see references,  section 1.3).  Or, the realist might grant that the history of science presents a record of significant referential discontinuity, but contend that, nevertheless, it also presents a record of impressive continuity regarding what is properly endorsed by realism, as recommended by explanationists, entity realists, or structural realists (see references,  section 2.3).  (For other responses, see Leplin 1981; McAllister 1993; Chakravartty 2007a: ch. 2; Doppelt 2007; Nola 2008; Roush 2010, 2015; and Fahrbach 2011. Hardin &amp; Rosenberg 1982; Cruse &amp; Papineau 2002; and Papineau 2010 explore the idea that reference is irrelevant to approximate truth).