It has been argued that epistemological realism is the best, if not the only, way to make sense of the success of science. Larry Laudan is skeptical and seeks to question, “whether the realist’s assertions about the interrelations between truth, reference and success are sound.” (22) To do this Laudan sets up an overarching and flexible umbrella that he terms convergent epistemological realism (CER for short). CER is based on five claims that Laudan believes most realist hold, implicitly or explicitly, in some form:
R1) Scientific theories (at least in the ‘mature’ sciences) are typically approximately true and more recent theories are closer to the truth than older ones in the same domain.
R2) The observational and theoretical terms within the theories of a mature science genuinely refer.
R3) Successful theories in any mature science will be such that they ‘preserve’ the theoretical relations and the apparent referents of earlier theories (i.e. earlier theories will be ‘limiting cases’ of later theories).
R4) Acceptable new theories do and should explain why their predecessors were successful insofar as there were successful…
R5) Theses (R1)-(R5) entail that (‘mature’) scientific theories should be successful: indeed these theses constitute the best, if not the only, explanation for the success of science. The empirical success of science (in the sense of giving detailed explanations and accurate predictions) accordingly provides striking empirical confirmation for realism. (20-21)
The realist makes, and indeed must make, a necessary connection between a scientific theory’s success and its claim to truth. In a somewhat Kuhnian move Laudan displays the contingency of such a connection by turning to history. On the one hand, there are many theories in the history of science that have referred (at least according to science’s present ontology) yet were not successful. (24-25) On the other hand, there have been many theories that were successful yet did not refer. (26-27) In fact, this is even the case for many theories whose central terms did not refer. (33) For Laudan the later undermines R2 to the extent that it suggests the contingency of any link between a theory’s success and its reference. This also undermines the realist’s claim that she can explain the success of science since this claim, in part, rested on the idea that scientific theories genuinely refer. In addition this undermines R1. This is because, for the realist, either the theory as a whole is true and testable or it is not. If only portions of it are testable, and not the entire theory as a whole, “then even highly successful theories may well have central terms which are non-referring and central tenets which, because untested, we have no grounds for believing to be approximately true. Under such circumstances, a theory might be highly successful and yet contain important constituents which were patently false.” (28) This, in turn, undermines the rational for R3, which is only needed if previous theories did refer.
Towards the end of his essay Laudan asks if realism can stand up to the same test as a scientific hypothesis must, i.e. “whether it has been subjected to a battery of tests; whether it has successfully made novel predictions; whether there is independent evidence for it.” Laudan’s answer is no. One may ask if the apparent success of science is not a confirmation of the realist hypothesis. Yet, any argument pointing towards an affirmation remains ad hoc since realism was created in order to explain the success of science. In short, any attempt to ground realism on the success of science is a grand adventure in petitio principii. In addition, Laudan finds no other grounds for realism to have made any better since of the success of science than an instrumentalist approach, let alone having made novel predictions. (46)