Ioannis Votsis

The pessimistic induction argument, most often associated with Larry Laudan, is now widely considered to be one of the main obstacles for realism. Put simply, the argument holds that since past predictively successful scientific theories have eventually been discarded, we have inductive evidence that our current theories will also be discarded one day. More precisely, Laudan undermines the inference from the explanatory and predictive success of a theory to its approximate truth and referential success. This paper criticises a particular kind of realist reply to Laudan.

Under what circumstances, if any, are we warranted to assert that a theory is true or at least approximately true? Scientific realists answer that such assertions are warranted only for those theories that enjoy explanatory and predictive success. A number of challenges to this answer have emerged, chief among them the argument from pessimistic meta-induction. According to this challenge, the history of science supplies ample evidence against realism in the form of successful theories that are now considered false. The main realist reaction to this challenge questions the legitimacy of the pessimistic meta-inductivist inference. Advocates of this approach argue that upon closer scrutiny the historical record can be reconciled with scientific realism. When a successful theory is abandoned, not all of its components are discarded but only those that are inessential or idle for the theory’s success. Their abandonment is thus inconsequential for the realist. So long as the essential components survive into the new theory there is no cause for alarm. More precisely, an outdated theory T which enjoyed some measure of success must, according to the realist, be: (i) partially true precisely because some of its theoretical claims are..

The concern with the objectivity of observations is as old as empirical study itself. Protagoras’ assertion that ‘Man is the measure of all things’, though not particularly directed at observations, raised general doubts concerning the objectivity of our beliefs. In the twentieth century, the concern has been brought under the banner ‘theory-ladenness of observation’. In simple terms, since observations are conducted and formulated in theory-specific contexts, they are inadvertently imbued with the prejudices of those contexts - the terms ‘theory’ and ‘observation’ are here broadly construed. Accordingly, it is argued, observations cannot be neutral in the testing of theories.

Consider the aims of the following three influential philosophical views. The semantic view of theories aims to supply the proper form and content of scientific theories. Structural realism aspires to delimit the epistemology and ontology of science. Mathematical structuralism seeks to reveal the epistemological and ontological nature of – you guessed it – mathematical objects. Given their divergent aims they may seem like unlikely bedfellows, but the semantic view of theories, structural realism and mathematical structuralism share enough ground to be able to benefit or suffer from some of the same reasons. What unites the three views is the purely structural analysis of their respective subject matter. The semantic view sees theories as nothing more than families of models, i.e. sets of structures. Representation, according to this view, is a matter of establishing mappings between some models of the theory and target domains. Structural realism judges scientific knowledge and perhaps even ontology to be wholly structural. Mathematical structuralism proclaims that the objects of mathematics are specifiable only up to isomorphism.

Kyle Stanford (2006) argues that the most serious and powerful challenge to scientific realism has been neglected. The problem of unconceived alternatives (PUA), as he calls it, holds that throughout history scientists have failed to conceive alternative theories roughly equally wellconfirmed (by the available evidence) to the theories of the day and, crucially, that such alternatives eventually were conceived and adopted by some section of the scientific community. PUA is a version of the argument from the underdetermination of theories by evidence (UTE) but departs from it in two significant ways: (i) there is a shift from artificially produced rival theories - of the kind typically talked about in the underdetermination debate - to actual rivals and (ii) there is a shift from empirically equivalent rivals to rivals that are equally well-confirmed by the available evidence at a given point in time. In this talk I will argue that by these shifts Stanford successfully manages to find more historical evidence for PUA (than do proponents of UTE), but only at the expense of making his thesis ineffectual.

This paper counters an objection raised against one of Bertrand Russell’s lesser-known epistemological views, viz. ‘‘structural realism’’ (SR). In short, SR holds that at most we have knowledge of the structure of the external (i.e., physical) world. M. H. A. Newman’s allegedly fatal objection is that SR is either trivial or false. I argue that the accusation of triviality is itself empty since it fails to establish that SR knowledge claims are uninformative. Moreover, appealing to Quine’s notion of ontological relativity, I suggest that far from being false, SR knowledge claims seem to be the most that we can hope for.