ORI GIN AL ARTICLE
Mechanistic Explanation: Integrating the Ontic and Epistemic
Received: 10 July 2013 / Accepted: 10 July 2013 Springer Science+Business Media Dordrecht 2013
Abstract Craver claims that mechanistic explanation is ontic, while Bechtel claims that it is epistemic. While this distinction between ontic and epistemic explanation originates with Salmon, the ideas have changed in the modern debate on mechanistic explanation, where the frame of the debate is changing. I will explore what Bechtel and Craver’s claims mean, and argue that good mechanistic explanations must satisfy both ontic and epistemic normative constraints on what is a good explanation. I will argue for ontic constraints by drawing on Craver’s work in
Sect. 2.1, and argue for epistemic constraints by drawing on Bechtel’s work in Sect. 2.2. Along the way, I will argue that Bechtel and Craver actually agree with this claim. I argue that we should not take either kind of constraints to be fundamental, in Sect. 3, and close in Sect. 4 by considering what remains at stake in making a distinction between ontic and epistemic constraints on mechanistic explanation. I suggest that we should not concentrate on either kind of constraint, to the neglect of the other, arguing for the importance of seeing the relationship as one of integration. 1 The Ontic–Epistemic Distinction for Mechanistic Explanation
The original distinction between ontic and epistemic explanation is due to Salmon and situated against the background of Hempel’s classic account of explanation, and related views. So, for example, Salmon writes: ‘In its classic form—the inferential version—the epistemic conception takes scientific explanations to be arguments.’
He contrasts this with his own conception of explanation: ‘The ontic conception sees explanations as exhibitions of the ways in which what is to be explained fits into natural patterns or regularities . . . [and] usually takes the patterns and regularities to be causal’ (Salmon 1984, p. 293). There are more versions of the
P. Illari (&)
University College London, London, UK e-mail: firstname.lastname@example.org 123
DOI 10.1007/s10670-013-9511-y epistemic conception, and further nuances of Salmon’s views worthy of study, but my aim here is to examine the debate currently under way in the mechanisms literature.
Carl Craver and William Bechtel have taken inspiration from Salmon’s distinction, and adopted its language, to disagree about the nature of mechanistic explanation: Bechtel claims that mechanistic explanations are epistemic, while
Craver claims they are ontic. And this dispute is important to the mechanisms literature widely, because most new mechanistas agree with Craver. As Wright points out: ‘Perhaps because of their common interests in causality, most New
Mechanists have hitched their wagon to Wesley Salmon’s ontic conception of scientific explanation’ (Wright 2012, p. 376). Certainly Machamer et al. (2000) gives an ontic conception, Machamer (2004) seems to maintain it, and Glennan (2002, 2005) explicitly agrees. So if any of Bechtel’s criticisms are right, that is of wide importance to the mechanisms literature. Since only Bechtel and Craver of the major mechanistas defend their view in any extended way, I will focus on their work. Further, their work needs examination as what their specific claims are takes some work to understand, as they do not simply adopt a pre-existing clear distinction.
I begin with Craver. There are two different things that Craver classifies as ontic explanation, which may both derive from Salmon. First, Craver holds that mechanistic explanation involves fitting a phenomenon into the causal structure of the world: ‘I argue that good explanations in neuroscience show how phenomena are situated within the causal structure of the world (Salmon 1984; Craver 2007, p. 21)’. Here, explanation involves showing or exhibiting something about the causal structure of the world. Elsewhere, though, Craver says: ‘Other times, the term explanation refers to an objective portion of the causal structure of the world, to the set of factors that bring about or sustain a phenomenon (call them objective explanations). . . . Objective explanations are not texts; they are full-bodied things.
They are facts, not representations’ (Craver 2007, p. 27). Here, any reference to exhibition or showing is dropped. In this case the mechanism itself explains.
Bechtel holds that explanation is deeply concerned with understanding, and is essentially a human activity: ‘Explanation is fundamentally an epistemic activity performed by scientists’ (Bechtel 2008, p. 18). Given Bechtel’s concern with understanding and the cognitive abilities of human beings in his overarching project of understanding mechanistic explanation, it is easy to assimiliate his view to a psychologism where an explanation is anything that generates an entirely subjective ‘aha’ feeling on the part of the receiver of the explanation. This is a view that may well be rejected on the grounds that science is not in the business of making people merely feel as though they have understood the world. However, as Waskan (2011) argues, there is also a ‘success’ interpretation of ‘understanding’, which requires success in understanding the real world. As Bechtel firmly classifies his own view as epistemic, it seems likely that this is the sense he intends, which is consistent with the idea that explanations generate knowledge. So Bechtel seems to agree with his close collaborator: ‘It is surely right to say that mechanistic explanatory texts aim to increase knowledge about mechanisms. . .. Obviously, knowledge of how things work is an epistemic matter if anything is, which is just to say that analysis of
P. Illari 123 mechanistic explanatory texts properly requires a broadly epistemic conception of mechanistic explanation’ (Wright 2012, p. 382). So, for Bechtel, and Wright, mechanistic explanations are texts, or descriptions and so on, that aim to increase knowledge about mechanisms. For the epistemic conception, the text or description explains. There are further complexities of Bechtel’s real concern for the needs of actual cognizers in mechanistic explanation, which I will return to later, applying