Two arguments for scientific realism unified David Harker East Tennessee State University, Department of Philosophy, Johnson City TN 37614, USA article info Article history: Received 20 August 2008 Received in revised form 24 June 2009 Keywords: Scientific realism Pessimistic meta-induction Success Progress Aether Novelty abstract Inferences from scientific success to the approximate truth of successful theories remain central to the most influential arguments for scientific realism. Challenges to such inferences, however, based on rad- ical discontinuities within the history of science, have motivated a distinctive style of revision to the ori- ginal argument. Conceding the historical claim, selective realists argue that accompanying even the most revolutionary change is the retention of significant parts of replaced theories, and that a realist attitude towards the systematically retained constituents of our scientific theories can still be defended. Selective realists thereby hope to secure the argument from success against apparent historical counterexamples. Independently of that objective, historical considerations have inspired a further argument for selective realism, where evidence for the retention of parts of theories is itself offered as justification for adopting a realist attitude towards them. Given the nature of these arguments from success and from retention, a reasonable expectation is that they would complement and reinforce one another, but although several theses purport to provide such a synthesis the results are often unconvincing. In this paper I reconsider the realist’s favoured type of scientific success, novel success, offer a revised interpretation of the concept, and argue that a significant consequence of reconfiguring the realist’s argument from success accordingly is a greater potential for its unification with the argument from retention. Ó 2010 Elsevier Ltd. All rights reserved. When citing this paper, please use the full journal title Studies in History and Philosophy of Science 1. Introduction Inferences from scientific success to the approximate truth of successful theories remain central to the most influential argu- ments for scientific realism. Success can be construed in a variety of ways, but verified novel predictions are often considered the most compelling examples for the claim that science couldn’t be that successful if our theories weren’t at least approximately true. 1 Consider Fresnel’s theory’s verified prediction that when a narrow beam of light is directed towards an opaque disc or sphere a white spot will appear at the centre of the shadow that’s created. Intuitively it can seem just too incredible that Fresnel’s theory should correctly anticipate the unexpected phenomenon, yet the theory not be at least approximately true. Nevertheless, even theories that enjoy novel suc- cess are sometimes replaced, and sometimes replaced by theories with radically distinctive ontologies. Historical examples of radical shifts in scientific understanding create well known challenges for the realist. Where the incongru- ence between two successful theories is sufficiently acute, for in- stance, we can no longer describe each as approximately true without stretching the notion so thin as to render it useless for realist ends. Examples of such incongruence thus appear to under- mine the realist’s conviction that success is a reliable indicator of truth. 2 Historical considerations seem to recommend we relinquish realist sympathies. 0039-3681/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.shpsa.2010.03.006 E-mail address: HARKERD@mail.etsu.edu 1 Musgrave (1988) argues that ‘careful realists’, at least since Whewell, have always intended the verification of novel predictions in discussions of scientific success. Worrall (1989b), Leplin (1997), and Psillos (1999) each argue the importance of peculiarly novel success; many recent antirealist arguments also now pay particular attention to such results. 2 The most famous example of the antirealist challenge from the history of science is Laudan (1981). Many interpret Laudan as defending a (pessimistic meta-) induction that implies our own theories are destined for replacement by new theories, radically incongruent with our own. Others (for example Ladyman, 2002) argue convincingly that Laudan should instead be understood as merely providing examples that at least appear to undermine the credibility of the realist’s inference from success to approximate truth. On either interpretation historical considerations present the realist with a significant challenge. Studies in History and Philosophy of Science 41 (2010) 192–202 Contents lists available at ScienceDirect Studies in History and Philosophy of Science journal homepage: www.elsevier.com/locate/shpsa