Understanding as explanatory knowledge: The case of Bjorken scaling Kareem Khalifa, Michael Gadomski Department of Philosophy, Middlebury College, Middlebury, VT 05753, USA article info Article history: Received 26 February 2013 Received in revised form 18 June 2013 Available online 29 July 2013 Keywords: Understanding Explanation Knowledge James Bjorken Particle physics abstract In this paper, we develop and refine the idea that understanding is a species of explanatory knowledge. Specifically, we defend the idea that S understands why p if and only if S knows that p, and, for some q, S’s true belief that q correctly explains p is produced/maintained by reliable explanatory evaluation. We then show how this model explains the reception of James Bjorken’s explanation of scaling by the broader physics community in the late 1960s and early 1970s. The historical episode is interesting because Bjor- ken’s explanation initially did not provide understanding to other physicists, but was subsequently deemed intelligible when Feynman provided a physical interpretation that led to experimental tests that vindicated Bjorken’s model. Finally, we argue that other philosophical models of scientific understanding are best construed as limiting cases of our more general model. Ó 2013 Elsevier Ltd. All rights reserved. When citing this paper, please use the full journal title Studies in History and Philosophy of Science 1. Introduction Recently, the concept of understanding has garnered increasing attention among philosophers of science. 1 Yet, there has been little consensus on what understanding actually is. In this paper, we argue that understanding is knowledge of a phenomenon plus knowledge of an explanation achieved through reliable explanatory evaluation (Section 2). We then use a brief episode in the recent history of par- ticle physics to showcase various features of our account (Sections 3 and 4). Finally, we argue that our view fares better than two alterna- tives ably developed by Robert Batterman and Henk de Regt (Section 5). 2. Understanding as explanatory knowledge In this section, we present our account of understanding (2.1), and then present our strategy for illustrating its plausibility (2.2). The remainder of the paper then executes that strategy. 2.1. The explanatory knowledge model of understanding According to our account of understanding: (EK) S understands why p if and only if: (a) S knows that p; and (b) For some q, S’s true belief that q correctly explains p is produced/maintained by reliable explanatory evaluation. Since it is widely (though not universally) held that knowledge is reliably formed true belief, understanding why p is thus knowl- edge that p plus knowledge that q correctly explains p. 2 For this reason we call this the Explanatory Knowledge (EK) model of understanding. Such a view has a venerable history in the philosophy of sci- ence. Grimm (2006) cites Achinstein, Kitcher, Lipton, Salmon, and Woodward as endorsing the view that understanding is a species of knowledge. However, these views focus on the concept of expla- nation, while paying relatively little attention to the concept of 0039-3681/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.shpsa.2013.07.001 E-mail addresses: kkhalifa@middlebury.edu (K. Khalifa), mgadomski@middlebury.edu (M. Gadomski) 1 See Batterman (2000, 2002), De Regt & Dieks (2005), De Regt, Leonelli, & Eigner (2009), Grimm (2006) and Trout (2002). 2 Knowledge requires an additional, ‘‘anti-Gettier condition.’’ Khalifa (2013) argues that reliable explanatory evaluation satisfies this condition. Studies in History and Philosophy of Science 44 (2013) 384–392 Contents lists available at SciVerse ScienceDirect Studies in History and Philosophy of Science journal homepage: www.elsevier.com/locate/shpsa