- Email: [email protected]
Understanding and explanation: Living apart together?
Studies in History and Philosophy of Science 44 (2013) 505–509
Contents lists available at SciVerse ScienceDirect
Studies in History and Philosophy of Science journal homepage: www.elsevier.com/locate/shpsa
Understanding and explanation: Living apart together? Henk W. de Regt VU University Amsterdam, De Boelelaan 1105, 1081 HV Amsterdam, The Netherlands
a r t i c l e
i n f o
Article history: Available online 28 December 2012 Keywords: Scientific understanding Explanation
a b s t r a c t This introductory essay to the special issue on ‘understanding without explanation’ provides a review of the debate in philosophy of science concerning the relation between scientific explanation and understanding, and an overview of the themes addressed in the papers included in this issue. In recent years, the traditional consensus that understanding is a philosophically irrelevant by-product of scientific explanations has given way to a lively debate about the relation between understanding and explanation. The papers in this issue defend or challenge the idea that understanding is a cognitive achievement in its own right, rather than simply a derivative or side-effect of scientific explanations. Ó 2012 Elsevier Ltd. All rights reserved.
When citing this paper, please use the full journal title Studies in History and Philosophy of Science
1. Introduction It might seem a commonplace to say that the aim of science is to provide understanding of the world around us. Scientists and laypeople alike will typically regard understanding as one of the most important and highly-valued products of scientific research. This may seem unsurprising: Who would doubt that science has given us understanding of such diverse phenomena as the motion of the heavenly bodies, the tides, the weather, earthquakes, the formation of rocks and fossils, electricity and magnetism, and the evolution of species? Climate scientists, who try to understand the process of global warming and other climate changes, provide a contemporary example of the centrality of understanding as an aim of science. The main task of the Intergovernmental Panel on Climate Change (IPCC) is to assess progress in scientific understanding of climate change, as can be gleaned from its most recent report. In the one-page introduction of the technical summary of Climate Change 2007: The Physical Science Basis (IPCC, 2012), the terms ‘understand’ or ‘understanding’ are used nine times. Here is a typical quote: ‘‘While this report provides new and important policy-relevant information on the scientific understanding of climate change, the complexity of the climate system and the multiple interactions that determine its behaviour impose limitations on our ability to understand fully the future course of Earth’s global E-mail address: [email protected] 0039-3681/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.shpsa.2012.12.002
climate. There is still an incomplete physical understanding of many components of the climate system and their role in climate change’’ (IPCC, 2012, my italics). For a long time, however, philosophers of science have largely ignored the topic of understanding and focused instead on explanation. The main reason was that Carl Hempel’s influential approach to scientific explanation denied that understanding is an epistemic aim of science, and assumed it to be a merely psychological byproduct of explanations. Accordingly, understanding was viewed as a topic that was perhaps interesting for psychologists and historians of science but was of no value for a philosophical analysis of science. This situation has changed dramatically in recent years. Understanding has become a hot topic in philosophy of science, as is shown by the fact that high-profile journals in the field regularly publish papers on it. Recent examples are Grimm (2010), Khalifa (2012a, 2012b), Newman (2012), de Regt (2009), and Wilkenfeld (2011). While these authors differ in their views about the exact characterization of understanding, its relation to explanation and the way to achieve it, they all agree that it is a legitimate philosophical topic in its own right. This idea is also shared by the contributors to the volume Scientific Understanding: Philosophical Perspectives (de Regt, Leonelli, & Eigner, 2009), who investigate scientific understanding using a variety of approaches, and treat it as a notion that can be related to, but is not fully dependent on or inextricably connected to, explanation. In sum, the traditional consensus has given
506
H.W. de Regt / Studies in History and Philosophy of Science 44 (2013) 505–509
way to a lively debate about the relation between understanding and explanation. The present collection of papers, which originate from a workshop held at the Lorentz Center, Leiden, The Netherlands (May 31–June 4, 2010), aims to contribute to this debate by presenting in-depth studies of the role and status of understanding in science. The authors defend or challenge the idea that understanding is a cognitive achievement in its own right, rather than simply a derivative or side-effect of scientific explanations. They do so in various ways, using both systematic analyses and case studies of scientific practice. Thus, Michael Strevens and Victor Gijsbers develop general analyses of understanding, using examples from the natural sciences. By contrast, Frank Hindriks and Stephen Turner zoom in on the way understanding is achieved in the social sciences. In this introductory essay I will review the main positions in the debate about the relation between explanation and understanding through a critical discussion of some recent contributions. Subsequently, I will highlight the main themes discussed in the papers collected in this special issue, and evaluate their views on the prospects of a healthy relationship between understanding and explanation. 2. Looking back: scenes from a marriage In his 1965 essay ‘‘Aspects of Scientific Explanation,’’ which gives an exhaustive account of the covering law model, Hempel observes that there is a link between explanation and understanding: ‘‘Very broadly speaking, to explain something to a person is to make it plain and intelligible to him, to make him understand it’’ (Hempel, 1965, p. 425). Hempel notes, however, that whether or not a given explanation is intelligible to a specific person and makes him understand the phenomenon, will vary and is a relative and subjective matter. This is a pragmatic aspect of explanation, which may be an interesting subject for empirical investigation but is irrelevant for a logical analysis of explanations. According to Hempel, it may therefore safely be ignored by philosophers of science, who should be interested only in the objective features of explanations. If there is a philosophically relevant sense of understanding, it is ‘‘understanding in the theoretical, or cognitive, sense of exhibiting the phenomenon to be explained as a special case of some general regularity’’ (Hempel, 1965, p. 257). But this objective kind of understanding is obviously nothing else than explanation of phenomena by subsuming them under covering laws. In sum, on Hempel’s view, philosophers should either ignore understanding as a subjective by-product of scientific explanation, or simply identify it with explanation. Although later philosophers of explanation, such as Michael Friedman, Philip Kitcher and Wesley Salmon, were less dismissive of the notion of understanding, only recently has understanding become a separate subject of philosophical study.1 While not denying that explanation and understanding are intimately related, many contemporary authors claim that understanding can and should be analyzed independently of explanation and they propose different accounts of it. My own account emphasizes that scientific understanding requires that relevant theories are intelligible, which in turn demands that the properties of these theories are appropriately geared to the skills of the scientists who use them. As such, intelligibility is a pragmatic condition that typically varies with the context (de Regt, 2009; de Regt & Dieks, 2005). Recently, however, a criticism of the distinctiveness of understanding has been advanced by Kareem Khalifa, who defends the thesis that ‘‘Any philosophically rele-
vant ideas about scientific understanding can be captured by philosophical ideas about the epistemology of scientific explanation without loss’’ (Khalifa, 2012a, p. 17). Khalifa focuses on three specific accounts of understanding, and argues that all three can be replaced by a theory of explanation and that such a replacement has in fact several advantages. I will not go into the details of Khalifa’s arguments here.2 I only note that, even if valid, they do not definitively refute the view that a distinctive analysis of understanding is possible (Khalifa himself admits this much). To achieve this, a more general argument would need to be developed. By contrast, arguments for considering understanding as a distinctive notion are presented by Peter Lipton. In his paper ‘Understanding without explanation’ (2009), Lipton argues with characteristic clarity and lucidity that understanding and explanation should be distinguished. Lipton’s aim is a modest one: he does not intend to argue that understanding is more important than explanation, or that scientists prefer understanding above explanation, nor for any other kind of primacy or superiority of understanding. He only wants to prove that there is ‘‘a gap between explanation and understanding’’ (Lipton, 2009, p. 52), which would imply that investigating the nature of scientific understanding is a legitimate and interesting philosophical topic in its own right. Lipton (2009, p. 43) observes that ‘‘it is tempting to identify understanding with having an explanation.’’ But, he continues, how does having an explanation of a phenomenon bring us from simply knowing that it occurs to understanding why it occurs? The latter involves an extra cognitive achievement, which implies that understanding must be identified with the cognitive benefits that explanations provide, rather than with the explanation itself. Lipton considers four benefits that are typically regarded as forms of understanding: knowledge of causes, necessity, possibility and unification. His strategy is to investigate whether these benefits can also be achieved through other means than explanation. If this turns out to be the case, then we have genuine cases of understanding without explanation, which prove that ‘‘understanding is more extensive and more varied in its sources than those who would equate explanation and understanding allow’’ (Lipton, 2009, p. 44). As regards the benefit of causal knowledge, Lipton argues that this can take an implicit, non-linguistic form, and thus cannot be used for explanation, which is by nature linguistic and explicit. For example, by looking at a planetarium one may gain implicit, causal understanding of the retrograde motion of planets, even if one cannot explain this motion. Similarly, the benefit of unification can be obtained in ways that involve implicit knowledge. Here Lipton refers to Kuhn’s observation that scientists extend their knowledge on the basis of exemplars. They look for analogies between known exemplars and phenomena in a new domain, which may unify the different phenomena. Such reasoning by analogy requires implicit skills and therefore cannot be conceived as an explanatory activity. According to Lipton, one may also understand by seeing the necessity of a phenomenon while not yet having an explanation of it. Galileo’s famous thought experiment that shows that the acceleration of bodies is independent of their mass is an example. Although it proves the necessity of the independence, and thus provides understanding, it does not explain why this independence holds. Finally, Lipton (2009, pp. 51–52) argues that sometimes potential (but false) explanations furnish actual understanding, which implies that one has understanding but not an explanation. Lipton’s thesis that understanding without explanation is possible is criticized by Khalifa (2012b), who defends ‘explanatory
1 A precursor is Peter Achinstein’s The Nature of Explanation (1983), which pays detailed attention to the relation between explanation and understanding. His pragmatic theory of explanation places the pragmatic dimension of explanation that Hempel wanted to neglect at the center of attention. Achinstein’s theory has not had as much impact as the rival theories of Kitcher and Salmon, however. 2 I will try to rebut Khalifa’s criticism of my own theory of scientific understanding elsewhere.
H.W. de Regt / Studies in History and Philosophy of Science 44 (2013) 505–509
idealism.’ This is the thesis that while there may be ways to achieve understanding without explanation, these ‘‘ought to be assessed by how well they replicate the understanding provided by knowledge of a good and correct explanation’’ (Khalifa, 2012b, p. 2). Moreover, he argues that for every case of non-explanatory understanding of a phenomenon P there exists an explanation that would give us greater understanding of P, and attempts to show this for the four cases discussed by Lipton. As regards unification through exemplars, for example, he contends that the alternative of explanatory unification (in Kitcher’s sense) provides all the knowledge that tacit understanding supplies plus knowledge of specific explanations that can be inferred from the general schema (Lipton’s other examples are treated in a similar manner). In my view, however, Khalifa misses the main point of Lipton’s argument. Even if we agree with Khalifa’s analyses of specific cases and accept that ideally one can construct explanations of the phenomena in question, this does not yet show that understanding is actually reducible to or less valuable than explanation. Lipton’s cases of understanding without explanation are compatible with the claim that explanation is an (ideal) aim of science. They do demonstrate, however, that scientific understanding of phenomena can exist independently of explanation, that it is legitimate and important to distinguish between understanding and explanation, and that understanding is a distinctive epistemic aim of science. One may accept explanatory idealism, and still acknowledge the importance of non-explanatory understanding in the reality of scientific practice. If one prefers a descriptively accurate philosophy of science over an idealized picture of it, the notion of understanding cannot be eliminated. 3. Looking ahead: relationship counselling The papers collected in this special issue continue the debate about the relation between understanding and explanation in various ways. While three authors defend a conception of understanding that is independent of explanation, Michael Strevens argues for the contrary position. In his paper ‘‘No understanding without explanation,’’ Strevens defends the ‘‘simple view,’’ that is, the thesis that ‘‘an individual has scientific understanding of a phenomenon just in case they grasp a correct scientific explanation of that phenomenon’’. Strevens’ position is thus congenial to the traditional view that understanding, if it has any philosophical (epistemic) bite, must either be identified with explanation itself or with the grasping of it. On Strevens’ view, understanding is inherently associated with explanations and cannot exist independently of explanation: ‘‘There is no route to scientific understanding that does not go by way of scientific explanation’’. While he does not want to brush away understanding as an irrelevant and unimportant psychological by-product of explanation, he claims that it is a derivative of explanation: ‘‘the norms of correct scientific explanation logically precede and participate in determining the norms of understanding.’’ Strevens’ claim that understanding is the mental act of ‘grasping a correct explanation’ invites an analysis of the notion of ‘grasping’ (as well as of ‘correctness’ and ‘explanation’). He defines ‘grasping’ as a kind of understanding, where he avoids circularity by distinguishing between ‘understanding why’ and ‘understanding that’: we understand why a phenomenon occurs in case we understand that the proposed explanation correctly describes the facts and that they conform to the structure prescribed by the explanation (e.g., a deductive or causal structure). So, like Lipton, Strevens analyzes understanding why as a specific kind of knowledge. He claims that the ‘‘hard philosophical work’’ is to explicate the notions of ‘explanation’ and of ‘understanding that’; as soon as we have succeeded in this, the notion of ‘understanding why’ has been clarified as well. Strevens distinguishes a third type, namely
507
‘understanding with,’ which applies to understanding theories that we use in explanations. Understanding with comprises the ability to construct an (actual or potential) explanation, and is a precondition for understanding why. Finally, Strevens holds that grasping an explanation does not imply the ability to make it explicit. So he resists Lipton’s (2009) argument that tacit understanding (e.g. of a causal model) cannot coincide with explanation. He also argues against two other examples that Lipton presents in order to show that understanding may be achieved without explanation. In contrast to Strevens, Victor Gijsbers defends the idea that there can be understanding without explanation. In his paper ‘‘Understanding, explanation and unification,’’ Gijsbers argues that there are (at least) two types of scientific understanding, of which only one is inherently related to explanation. Gijsbers starts his investigation into the possibility of understanding without explanation by exploring Lipton’s suggestions. He rejects Lipton’s claim that non-linguistic understanding (for example, as gained by looking at a planetarium) does not involve explanation, and argues that one may have an explanation even if one cannot express it linguistically. But Gijsbers agrees with Lipton’s thesis that the application of Kuhnian exemplars may lead to genuine understanding without explanation, and he elaborates this idea in more detail. As mentioned above, Lipton identifies Kuhnian exemplars with the cognitive benefit of unification because exemplars allow us to see similarities between different phenomena—they provide knowledge of how phenomena fit together. Gijsbers agrees and adds an argument that unification is neither necessary nor sufficient for explanation (see also Gijsbers, 2007). This entails the possibility that understanding is obtained by means of ‘pure’ unification bypassing explanation. According to Gijsbers, such ‘pure’ unification can be found in the activity of classification: if phenomena are unified on the basis of their perceived similarities, this amounts to classifying them and produces understanding without explanation. As an example of such understanding-providing classification, Gijsbers discusses biological classification as practiced in the eighteenth century. Classifying various animals on the basis of their anatomical features allowed biologists to make predictions, which is a cognitive achievement that deserves to be called understanding. It cannot be regarded as explanation, however, because it does not show how the relevant features of animals are determined (for example, causally or nomologically). Accordingly, classification and explanation both produce understanding, but in different ways: explanations identify ‘vertical’ connections via relations of determination, while unifying classifications highlight ‘horizontal’ connections via relations of ‘kinship’. This observation induces Gijsbers to advance a general definition of scientific understanding in terms of seeing connections between individual phenomena. Gijsbers’ account of horizontal and vertical modes of understanding invites a comparison with the views of Michael Friedman and Philip Kitcher, who observed that unification and causal explanation provide, respectively, top-down (or global) and bottom-up (or local) understanding. While the spatial metaphors differ, all three authors acknowledge the existence of complementary types of understanding (cf. de Regt, 2006). A different argument for the possibility of scientific understanding without explanation is given by Frank Hindriks in his paper ‘‘Explanation, understanding, and unrealistic models.’’ Hindriks focuses on the use of models to achieve understanding in economics. The models used in economic explanations are typically highly abstract and idealized: they entail regularities that cannot be found in the real world (The Modigliani-Miller theorem in financial economics is an example). The question arises what economists explain, if anything, by means of these models. Hindriks discusses two influential accounts of economic explanation, by Dan Hausman and Nancy Cartwright, and concludes that both fail
508
H.W. de Regt / Studies in History and Philosophy of Science 44 (2013) 505–509
because they wrongly demand that economic model regularities obtain, which is rarely the case. Hindriks develops an alternative view of explanation in economics, which he calls ‘explanation by relaxation’. On this view, explanations in economics are contrastive: the implications of an abstract and idealized model are compared with those of a relatively realistic model that is obtained by relaxing some assumptions of the original model. On this account, economists do not explain model regularities but rather explain why these regularities fail to obtain. While abstract and idealized models do not explain the regularities that obtain in the real world, they do provide understanding by describing mechanisms that would operate in the absence of any interfering factors. Such a mechanism does exist in the real world: it is ‘‘a stable configuration of causal powers’’. We can obtain understanding of it by, first, constructing an unrealistic ‘basic’ model which gives us knowledge of how the mechanism operates without interference, and subsequently, by discovering how the mechanism is affected by some major interfering factors. If these two conditions have been met, we understand how the mechanism works. However, we have not explained any observed or observable phenomenon; we merely possess a non-factive ‘would-be explanation’ of counterfactual regularities—those that would have obtained in the absence of the interfering factors. Hindriks suggests that this allows for understanding without explanation. To be sure, economists may want to explain why particular model regularities do not occur, and they can do so via explanation by relaxation, which involves understanding of relevant mechanisms. However, even without such contrastive explanations, the economists have gained understanding of mechanisms through basic models. Such understanding is scientifically relevant and can exist without explanation. Hindriks’ paper is concerned with economics, a social science that is often regarded as relatively close to the natural (mathematical) sciences, at least in its methods. What about other social and human sciences? One might think that understanding is an even more central element in these sciences. Indeed, as Johann Gustav Droysen and Wilhelm Dilthey suggested long ago, understanding (Verstehen) can be regarded as the distinctive goal of human sciences (Geisteswissenschaften) such as history, in contrast to the natural sciences, that aim at explanation (Erklären). If we accept this distinction, then it may seem that understanding without explanation is the rule outside natural science. But it is not that simple: even if the distinction is viable, it is blurred and many social sciences must either be located in a grey in-between area or they cross the distinction. Hindriks sidesteps these issues and treats economics as a science which differs from the natural sciences only in its topic and not in its methods or aims. Stephen Turner, by contrast, focuses on how explanations in social science differ from natural-scientific ones. The central concern of his paper, ‘‘Where explanation ends: Understanding as the place the spade turns in the social sciences,’’ is the question of when explanations in social science can be regarded as complete. His investigations of the problems of social-scientific explanation lead to the conclusion that the essential difference between the natural and the social sciences lies in the type of understanding that plays a role in explanations. Turner argues that in social science, explanations are complete only if they are grounded in what Max Weber has called ‘direct understanding.’ Direct understanding is observational and non-inferential: it occurs when we directly understand the meaning of a given act or verbal utterance. Understanding motives or intentions of actors, by contrast, is indirect: we infer them from what we observe together with circumstantial and causal knowledge. Weber calls such indirect understanding ‘explanatory understanding.’ Using an example from epidemiology, in which the relation between maternal obesity and infant mortality is investigated, Turner
shows that attempts to find causal structure always lead to a regress, because prior causal knowledge is needed in order to determine which relations are causal and which are not. He concludes that this can only be stopped if we understand the meaning that the involved actors attach to obesity: ‘‘This is where the regress ends, and where the explanation becomes [. . .] complete: there is nothing in the way of justification beyond direct understanding as defined by Weber’’. A currently popular way of distinguishing between complete social-scientific explanations and mere descriptions of statistical correlations is to demand that explanations describe mechanisms. The latter would be intelligible and provide understanding, while the former can only be used for predictions. As mentioned above, in the context of Hindriks’ paper, mechanisms play a key role in economic explanations as well. Turner asks when a mechanism explanation is truly complete. Like Hindriks, he observes that the mechanisms that social scientists describe in their models are highly abstract and idealized, and he compares them to Weberian ideal-types. Ideal-types are intelligible because of their clarity and simplicity, but moreover because they are based on direct and indirect understanding of actions. It is instructive to compare Turner’s and Hindriks’ analyses of the roles of abstract and idealized mechanisms in social-scientific explanation. Both identify such mechanisms (called ‘basic mechanisms’ by Hindriks and ‘ideal-types’ by Turner) as the sources of understanding. But while Hindriks takes the intelligibility of basic mechanisms for granted, Turner traces the intelligibility of idealtypes to our direct understanding of the meaning of relevant actions and behavior. The analyses of both Hindriks and Turner imply that understanding may exist without explanation, but for different reasons. On Hindriks’ account, understanding without explanation is possible because basic mechanisms can produce understanding even if they do not explain actually observed correlations. On Turner’s account, by contrast, understanding (in its direct form) is required to complete an explanation: it is ‘‘where explanation ends.’’ In other words, explanation depends on direct understanding: explanation cannot do without understanding, but understanding does not require explanation. In sum, the papers collected in this special issue investigate the relation between scientific understanding and explanation in various ways and present different viewpoints. Both Hindriks and Turner argue that in the social sciences understanding is possible independently of explanation. Moreover, according to Turner, social-scientific explanation must be grounded in understanding; without it remains incomplete. Gijsbers makes a case for the idea of understanding without explanation on a different, more general level: he argues that unification by means of classification provides understanding but no explanation. Such non-explanatory understanding can in principle be obtained in both natural and social sciences. While not denying that explanation and understanding may be intimately related, Gijsbers, Hindriks, and Turner regard understanding as a cognitive achievement with a life of its own. Strevens, by contrast, defends the Hempelian idea that scientific understanding is inherently associated with explanation. On his view, understanding cannot live without explanation, while explanation can perfectly well do without understanding. Thus, the authors arrive at diverging conclusions on how understanding and explanation relate to each other. Nevertheless, they take steps in the right direction. For a long time the marriage between explanation and understanding was taken for granted and left unanalyzed. The essays in this special issue are meant to change this unhappy situation and contribute to a deepening of our understanding of the relation. Do understanding and explanation need each other, or should they go their own way? In the interest of a healthy relationship, living apart together seems advisable, at least for the time being.
H.W. de Regt / Studies in History and Philosophy of Science 44 (2013) 505–509
Acknowledgements I thank the Lorentz Center (University of Leiden) and the Netherlands Institute for Advanced Study (NIAS, Wassenaar) for hosting, facilitating, and supporting the Lorentz Workshop Understanding and the Aims of Science (31 May–4 June 2010), where the papers were first presented. James McAllister is thanked for co-organizing the workshop and for helping with the start-up of this publication project, Hans Radder for his comments on an earlier version of this introductory essay, and the referees for reviewing the submitted papers. References Achinstein, P. (1983). The nature of explanation. New York: Oxford University Press. de Regt, H. W. (2006). Wesley Salmon’s complementarity thesis: Causalism and unificationism reconciled? International Studies in the Philosophy of Science, 20, 129–147. de Regt, H. W. (2009). The epistemic value of understanding. Philosophy of Science, 76(5), 585–597. de Regt, H. W., & Dieks, D. (2005). A contextual approach to scientific understanding. Synthese, 144(1), 137–170.
509
de Regt, H. W., Leonelli, S., & Eigner, K. (2009). Scientific understanding: Philosophical perspectives. Pittsburgh, PA: University of Pittsburgh Press. Gijsbers, V. (2007). Why unification is neither necessary nor sufficient for explanation. Philosophy of Science, 74, 481–500. Grimm, S. R. (2010). The goal of explanation. Studies in History and Philosophy of Science A, 41(4), 337–344. Hempel, C. G. (1965). Aspects of scientific explanation and other essays in the philosophy of science. New York: The Free Press. IPCC (2012). Climate change 2007 – The physical science basis, working group I contribution to the fourth assessment report of the IPCC. Cambridge: Cambridge University Press. Published online: Accessed 23.07.12. Khalifa, K. (2012a). Inaugurating understanding or repackaging explanation? Philosophy of Science, 79(1), 15–37. Khalifa, K. (2012b). The role of explanation in understanding. The British Journal for the Philosophy of Science, 63. http://dx.doi.org/10.1093/bjps/axr057. Lipton, P. (2009). Understanding without explanation. In H. W. de Regt, S. Leonelli, & K. Eigner (Eds.), Scientific understanding: Philosophical perspectives (pp. 43–63). Pittsburgh: University of Pittsburgh Press. Newman, M. (2012). An inferential model of scientific understanding. International Studies in the Philosophy of Science, 26(1), 1–26. Wilkenfeld, D. A. (2011). Understanding as representation manipulability. Synthese. http://dx.doi.org/10.1007/s11229-011-0055-x.
Contents lists available at SciVerse ScienceDirect
Studies in History and Philosophy of Science journal homepage: www.elsevier.com/locate/shpsa
Understanding and explanation: Living apart together? Henk W. de Regt VU University Amsterdam, De Boelelaan 1105, 1081 HV Amsterdam, The Netherlands
a r t i c l e
i n f o
Article history: Available online 28 December 2012 Keywords: Scientific understanding Explanation
a b s t r a c t This introductory essay to the special issue on ‘understanding without explanation’ provides a review of the debate in philosophy of science concerning the relation between scientific explanation and understanding, and an overview of the themes addressed in the papers included in this issue. In recent years, the traditional consensus that understanding is a philosophically irrelevant by-product of scientific explanations has given way to a lively debate about the relation between understanding and explanation. The papers in this issue defend or challenge the idea that understanding is a cognitive achievement in its own right, rather than simply a derivative or side-effect of scientific explanations. Ó 2012 Elsevier Ltd. All rights reserved.
When citing this paper, please use the full journal title Studies in History and Philosophy of Science
1. Introduction It might seem a commonplace to say that the aim of science is to provide understanding of the world around us. Scientists and laypeople alike will typically regard understanding as one of the most important and highly-valued products of scientific research. This may seem unsurprising: Who would doubt that science has given us understanding of such diverse phenomena as the motion of the heavenly bodies, the tides, the weather, earthquakes, the formation of rocks and fossils, electricity and magnetism, and the evolution of species? Climate scientists, who try to understand the process of global warming and other climate changes, provide a contemporary example of the centrality of understanding as an aim of science. The main task of the Intergovernmental Panel on Climate Change (IPCC) is to assess progress in scientific understanding of climate change, as can be gleaned from its most recent report. In the one-page introduction of the technical summary of Climate Change 2007: The Physical Science Basis (IPCC, 2012), the terms ‘understand’ or ‘understanding’ are used nine times. Here is a typical quote: ‘‘While this report provides new and important policy-relevant information on the scientific understanding of climate change, the complexity of the climate system and the multiple interactions that determine its behaviour impose limitations on our ability to understand fully the future course of Earth’s global E-mail address: [email protected] 0039-3681/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.shpsa.2012.12.002
climate. There is still an incomplete physical understanding of many components of the climate system and their role in climate change’’ (IPCC, 2012, my italics). For a long time, however, philosophers of science have largely ignored the topic of understanding and focused instead on explanation. The main reason was that Carl Hempel’s influential approach to scientific explanation denied that understanding is an epistemic aim of science, and assumed it to be a merely psychological byproduct of explanations. Accordingly, understanding was viewed as a topic that was perhaps interesting for psychologists and historians of science but was of no value for a philosophical analysis of science. This situation has changed dramatically in recent years. Understanding has become a hot topic in philosophy of science, as is shown by the fact that high-profile journals in the field regularly publish papers on it. Recent examples are Grimm (2010), Khalifa (2012a, 2012b), Newman (2012), de Regt (2009), and Wilkenfeld (2011). While these authors differ in their views about the exact characterization of understanding, its relation to explanation and the way to achieve it, they all agree that it is a legitimate philosophical topic in its own right. This idea is also shared by the contributors to the volume Scientific Understanding: Philosophical Perspectives (de Regt, Leonelli, & Eigner, 2009), who investigate scientific understanding using a variety of approaches, and treat it as a notion that can be related to, but is not fully dependent on or inextricably connected to, explanation. In sum, the traditional consensus has given
506
H.W. de Regt / Studies in History and Philosophy of Science 44 (2013) 505–509
way to a lively debate about the relation between understanding and explanation. The present collection of papers, which originate from a workshop held at the Lorentz Center, Leiden, The Netherlands (May 31–June 4, 2010), aims to contribute to this debate by presenting in-depth studies of the role and status of understanding in science. The authors defend or challenge the idea that understanding is a cognitive achievement in its own right, rather than simply a derivative or side-effect of scientific explanations. They do so in various ways, using both systematic analyses and case studies of scientific practice. Thus, Michael Strevens and Victor Gijsbers develop general analyses of understanding, using examples from the natural sciences. By contrast, Frank Hindriks and Stephen Turner zoom in on the way understanding is achieved in the social sciences. In this introductory essay I will review the main positions in the debate about the relation between explanation and understanding through a critical discussion of some recent contributions. Subsequently, I will highlight the main themes discussed in the papers collected in this special issue, and evaluate their views on the prospects of a healthy relationship between understanding and explanation. 2. Looking back: scenes from a marriage In his 1965 essay ‘‘Aspects of Scientific Explanation,’’ which gives an exhaustive account of the covering law model, Hempel observes that there is a link between explanation and understanding: ‘‘Very broadly speaking, to explain something to a person is to make it plain and intelligible to him, to make him understand it’’ (Hempel, 1965, p. 425). Hempel notes, however, that whether or not a given explanation is intelligible to a specific person and makes him understand the phenomenon, will vary and is a relative and subjective matter. This is a pragmatic aspect of explanation, which may be an interesting subject for empirical investigation but is irrelevant for a logical analysis of explanations. According to Hempel, it may therefore safely be ignored by philosophers of science, who should be interested only in the objective features of explanations. If there is a philosophically relevant sense of understanding, it is ‘‘understanding in the theoretical, or cognitive, sense of exhibiting the phenomenon to be explained as a special case of some general regularity’’ (Hempel, 1965, p. 257). But this objective kind of understanding is obviously nothing else than explanation of phenomena by subsuming them under covering laws. In sum, on Hempel’s view, philosophers should either ignore understanding as a subjective by-product of scientific explanation, or simply identify it with explanation. Although later philosophers of explanation, such as Michael Friedman, Philip Kitcher and Wesley Salmon, were less dismissive of the notion of understanding, only recently has understanding become a separate subject of philosophical study.1 While not denying that explanation and understanding are intimately related, many contemporary authors claim that understanding can and should be analyzed independently of explanation and they propose different accounts of it. My own account emphasizes that scientific understanding requires that relevant theories are intelligible, which in turn demands that the properties of these theories are appropriately geared to the skills of the scientists who use them. As such, intelligibility is a pragmatic condition that typically varies with the context (de Regt, 2009; de Regt & Dieks, 2005). Recently, however, a criticism of the distinctiveness of understanding has been advanced by Kareem Khalifa, who defends the thesis that ‘‘Any philosophically rele-
vant ideas about scientific understanding can be captured by philosophical ideas about the epistemology of scientific explanation without loss’’ (Khalifa, 2012a, p. 17). Khalifa focuses on three specific accounts of understanding, and argues that all three can be replaced by a theory of explanation and that such a replacement has in fact several advantages. I will not go into the details of Khalifa’s arguments here.2 I only note that, even if valid, they do not definitively refute the view that a distinctive analysis of understanding is possible (Khalifa himself admits this much). To achieve this, a more general argument would need to be developed. By contrast, arguments for considering understanding as a distinctive notion are presented by Peter Lipton. In his paper ‘Understanding without explanation’ (2009), Lipton argues with characteristic clarity and lucidity that understanding and explanation should be distinguished. Lipton’s aim is a modest one: he does not intend to argue that understanding is more important than explanation, or that scientists prefer understanding above explanation, nor for any other kind of primacy or superiority of understanding. He only wants to prove that there is ‘‘a gap between explanation and understanding’’ (Lipton, 2009, p. 52), which would imply that investigating the nature of scientific understanding is a legitimate and interesting philosophical topic in its own right. Lipton (2009, p. 43) observes that ‘‘it is tempting to identify understanding with having an explanation.’’ But, he continues, how does having an explanation of a phenomenon bring us from simply knowing that it occurs to understanding why it occurs? The latter involves an extra cognitive achievement, which implies that understanding must be identified with the cognitive benefits that explanations provide, rather than with the explanation itself. Lipton considers four benefits that are typically regarded as forms of understanding: knowledge of causes, necessity, possibility and unification. His strategy is to investigate whether these benefits can also be achieved through other means than explanation. If this turns out to be the case, then we have genuine cases of understanding without explanation, which prove that ‘‘understanding is more extensive and more varied in its sources than those who would equate explanation and understanding allow’’ (Lipton, 2009, p. 44). As regards the benefit of causal knowledge, Lipton argues that this can take an implicit, non-linguistic form, and thus cannot be used for explanation, which is by nature linguistic and explicit. For example, by looking at a planetarium one may gain implicit, causal understanding of the retrograde motion of planets, even if one cannot explain this motion. Similarly, the benefit of unification can be obtained in ways that involve implicit knowledge. Here Lipton refers to Kuhn’s observation that scientists extend their knowledge on the basis of exemplars. They look for analogies between known exemplars and phenomena in a new domain, which may unify the different phenomena. Such reasoning by analogy requires implicit skills and therefore cannot be conceived as an explanatory activity. According to Lipton, one may also understand by seeing the necessity of a phenomenon while not yet having an explanation of it. Galileo’s famous thought experiment that shows that the acceleration of bodies is independent of their mass is an example. Although it proves the necessity of the independence, and thus provides understanding, it does not explain why this independence holds. Finally, Lipton (2009, pp. 51–52) argues that sometimes potential (but false) explanations furnish actual understanding, which implies that one has understanding but not an explanation. Lipton’s thesis that understanding without explanation is possible is criticized by Khalifa (2012b), who defends ‘explanatory
1 A precursor is Peter Achinstein’s The Nature of Explanation (1983), which pays detailed attention to the relation between explanation and understanding. His pragmatic theory of explanation places the pragmatic dimension of explanation that Hempel wanted to neglect at the center of attention. Achinstein’s theory has not had as much impact as the rival theories of Kitcher and Salmon, however. 2 I will try to rebut Khalifa’s criticism of my own theory of scientific understanding elsewhere.
H.W. de Regt / Studies in History and Philosophy of Science 44 (2013) 505–509
idealism.’ This is the thesis that while there may be ways to achieve understanding without explanation, these ‘‘ought to be assessed by how well they replicate the understanding provided by knowledge of a good and correct explanation’’ (Khalifa, 2012b, p. 2). Moreover, he argues that for every case of non-explanatory understanding of a phenomenon P there exists an explanation that would give us greater understanding of P, and attempts to show this for the four cases discussed by Lipton. As regards unification through exemplars, for example, he contends that the alternative of explanatory unification (in Kitcher’s sense) provides all the knowledge that tacit understanding supplies plus knowledge of specific explanations that can be inferred from the general schema (Lipton’s other examples are treated in a similar manner). In my view, however, Khalifa misses the main point of Lipton’s argument. Even if we agree with Khalifa’s analyses of specific cases and accept that ideally one can construct explanations of the phenomena in question, this does not yet show that understanding is actually reducible to or less valuable than explanation. Lipton’s cases of understanding without explanation are compatible with the claim that explanation is an (ideal) aim of science. They do demonstrate, however, that scientific understanding of phenomena can exist independently of explanation, that it is legitimate and important to distinguish between understanding and explanation, and that understanding is a distinctive epistemic aim of science. One may accept explanatory idealism, and still acknowledge the importance of non-explanatory understanding in the reality of scientific practice. If one prefers a descriptively accurate philosophy of science over an idealized picture of it, the notion of understanding cannot be eliminated. 3. Looking ahead: relationship counselling The papers collected in this special issue continue the debate about the relation between understanding and explanation in various ways. While three authors defend a conception of understanding that is independent of explanation, Michael Strevens argues for the contrary position. In his paper ‘‘No understanding without explanation,’’ Strevens defends the ‘‘simple view,’’ that is, the thesis that ‘‘an individual has scientific understanding of a phenomenon just in case they grasp a correct scientific explanation of that phenomenon’’. Strevens’ position is thus congenial to the traditional view that understanding, if it has any philosophical (epistemic) bite, must either be identified with explanation itself or with the grasping of it. On Strevens’ view, understanding is inherently associated with explanations and cannot exist independently of explanation: ‘‘There is no route to scientific understanding that does not go by way of scientific explanation’’. While he does not want to brush away understanding as an irrelevant and unimportant psychological by-product of explanation, he claims that it is a derivative of explanation: ‘‘the norms of correct scientific explanation logically precede and participate in determining the norms of understanding.’’ Strevens’ claim that understanding is the mental act of ‘grasping a correct explanation’ invites an analysis of the notion of ‘grasping’ (as well as of ‘correctness’ and ‘explanation’). He defines ‘grasping’ as a kind of understanding, where he avoids circularity by distinguishing between ‘understanding why’ and ‘understanding that’: we understand why a phenomenon occurs in case we understand that the proposed explanation correctly describes the facts and that they conform to the structure prescribed by the explanation (e.g., a deductive or causal structure). So, like Lipton, Strevens analyzes understanding why as a specific kind of knowledge. He claims that the ‘‘hard philosophical work’’ is to explicate the notions of ‘explanation’ and of ‘understanding that’; as soon as we have succeeded in this, the notion of ‘understanding why’ has been clarified as well. Strevens distinguishes a third type, namely
507
‘understanding with,’ which applies to understanding theories that we use in explanations. Understanding with comprises the ability to construct an (actual or potential) explanation, and is a precondition for understanding why. Finally, Strevens holds that grasping an explanation does not imply the ability to make it explicit. So he resists Lipton’s (2009) argument that tacit understanding (e.g. of a causal model) cannot coincide with explanation. He also argues against two other examples that Lipton presents in order to show that understanding may be achieved without explanation. In contrast to Strevens, Victor Gijsbers defends the idea that there can be understanding without explanation. In his paper ‘‘Understanding, explanation and unification,’’ Gijsbers argues that there are (at least) two types of scientific understanding, of which only one is inherently related to explanation. Gijsbers starts his investigation into the possibility of understanding without explanation by exploring Lipton’s suggestions. He rejects Lipton’s claim that non-linguistic understanding (for example, as gained by looking at a planetarium) does not involve explanation, and argues that one may have an explanation even if one cannot express it linguistically. But Gijsbers agrees with Lipton’s thesis that the application of Kuhnian exemplars may lead to genuine understanding without explanation, and he elaborates this idea in more detail. As mentioned above, Lipton identifies Kuhnian exemplars with the cognitive benefit of unification because exemplars allow us to see similarities between different phenomena—they provide knowledge of how phenomena fit together. Gijsbers agrees and adds an argument that unification is neither necessary nor sufficient for explanation (see also Gijsbers, 2007). This entails the possibility that understanding is obtained by means of ‘pure’ unification bypassing explanation. According to Gijsbers, such ‘pure’ unification can be found in the activity of classification: if phenomena are unified on the basis of their perceived similarities, this amounts to classifying them and produces understanding without explanation. As an example of such understanding-providing classification, Gijsbers discusses biological classification as practiced in the eighteenth century. Classifying various animals on the basis of their anatomical features allowed biologists to make predictions, which is a cognitive achievement that deserves to be called understanding. It cannot be regarded as explanation, however, because it does not show how the relevant features of animals are determined (for example, causally or nomologically). Accordingly, classification and explanation both produce understanding, but in different ways: explanations identify ‘vertical’ connections via relations of determination, while unifying classifications highlight ‘horizontal’ connections via relations of ‘kinship’. This observation induces Gijsbers to advance a general definition of scientific understanding in terms of seeing connections between individual phenomena. Gijsbers’ account of horizontal and vertical modes of understanding invites a comparison with the views of Michael Friedman and Philip Kitcher, who observed that unification and causal explanation provide, respectively, top-down (or global) and bottom-up (or local) understanding. While the spatial metaphors differ, all three authors acknowledge the existence of complementary types of understanding (cf. de Regt, 2006). A different argument for the possibility of scientific understanding without explanation is given by Frank Hindriks in his paper ‘‘Explanation, understanding, and unrealistic models.’’ Hindriks focuses on the use of models to achieve understanding in economics. The models used in economic explanations are typically highly abstract and idealized: they entail regularities that cannot be found in the real world (The Modigliani-Miller theorem in financial economics is an example). The question arises what economists explain, if anything, by means of these models. Hindriks discusses two influential accounts of economic explanation, by Dan Hausman and Nancy Cartwright, and concludes that both fail
508
H.W. de Regt / Studies in History and Philosophy of Science 44 (2013) 505–509
because they wrongly demand that economic model regularities obtain, which is rarely the case. Hindriks develops an alternative view of explanation in economics, which he calls ‘explanation by relaxation’. On this view, explanations in economics are contrastive: the implications of an abstract and idealized model are compared with those of a relatively realistic model that is obtained by relaxing some assumptions of the original model. On this account, economists do not explain model regularities but rather explain why these regularities fail to obtain. While abstract and idealized models do not explain the regularities that obtain in the real world, they do provide understanding by describing mechanisms that would operate in the absence of any interfering factors. Such a mechanism does exist in the real world: it is ‘‘a stable configuration of causal powers’’. We can obtain understanding of it by, first, constructing an unrealistic ‘basic’ model which gives us knowledge of how the mechanism operates without interference, and subsequently, by discovering how the mechanism is affected by some major interfering factors. If these two conditions have been met, we understand how the mechanism works. However, we have not explained any observed or observable phenomenon; we merely possess a non-factive ‘would-be explanation’ of counterfactual regularities—those that would have obtained in the absence of the interfering factors. Hindriks suggests that this allows for understanding without explanation. To be sure, economists may want to explain why particular model regularities do not occur, and they can do so via explanation by relaxation, which involves understanding of relevant mechanisms. However, even without such contrastive explanations, the economists have gained understanding of mechanisms through basic models. Such understanding is scientifically relevant and can exist without explanation. Hindriks’ paper is concerned with economics, a social science that is often regarded as relatively close to the natural (mathematical) sciences, at least in its methods. What about other social and human sciences? One might think that understanding is an even more central element in these sciences. Indeed, as Johann Gustav Droysen and Wilhelm Dilthey suggested long ago, understanding (Verstehen) can be regarded as the distinctive goal of human sciences (Geisteswissenschaften) such as history, in contrast to the natural sciences, that aim at explanation (Erklären). If we accept this distinction, then it may seem that understanding without explanation is the rule outside natural science. But it is not that simple: even if the distinction is viable, it is blurred and many social sciences must either be located in a grey in-between area or they cross the distinction. Hindriks sidesteps these issues and treats economics as a science which differs from the natural sciences only in its topic and not in its methods or aims. Stephen Turner, by contrast, focuses on how explanations in social science differ from natural-scientific ones. The central concern of his paper, ‘‘Where explanation ends: Understanding as the place the spade turns in the social sciences,’’ is the question of when explanations in social science can be regarded as complete. His investigations of the problems of social-scientific explanation lead to the conclusion that the essential difference between the natural and the social sciences lies in the type of understanding that plays a role in explanations. Turner argues that in social science, explanations are complete only if they are grounded in what Max Weber has called ‘direct understanding.’ Direct understanding is observational and non-inferential: it occurs when we directly understand the meaning of a given act or verbal utterance. Understanding motives or intentions of actors, by contrast, is indirect: we infer them from what we observe together with circumstantial and causal knowledge. Weber calls such indirect understanding ‘explanatory understanding.’ Using an example from epidemiology, in which the relation between maternal obesity and infant mortality is investigated, Turner
shows that attempts to find causal structure always lead to a regress, because prior causal knowledge is needed in order to determine which relations are causal and which are not. He concludes that this can only be stopped if we understand the meaning that the involved actors attach to obesity: ‘‘This is where the regress ends, and where the explanation becomes [. . .] complete: there is nothing in the way of justification beyond direct understanding as defined by Weber’’. A currently popular way of distinguishing between complete social-scientific explanations and mere descriptions of statistical correlations is to demand that explanations describe mechanisms. The latter would be intelligible and provide understanding, while the former can only be used for predictions. As mentioned above, in the context of Hindriks’ paper, mechanisms play a key role in economic explanations as well. Turner asks when a mechanism explanation is truly complete. Like Hindriks, he observes that the mechanisms that social scientists describe in their models are highly abstract and idealized, and he compares them to Weberian ideal-types. Ideal-types are intelligible because of their clarity and simplicity, but moreover because they are based on direct and indirect understanding of actions. It is instructive to compare Turner’s and Hindriks’ analyses of the roles of abstract and idealized mechanisms in social-scientific explanation. Both identify such mechanisms (called ‘basic mechanisms’ by Hindriks and ‘ideal-types’ by Turner) as the sources of understanding. But while Hindriks takes the intelligibility of basic mechanisms for granted, Turner traces the intelligibility of idealtypes to our direct understanding of the meaning of relevant actions and behavior. The analyses of both Hindriks and Turner imply that understanding may exist without explanation, but for different reasons. On Hindriks’ account, understanding without explanation is possible because basic mechanisms can produce understanding even if they do not explain actually observed correlations. On Turner’s account, by contrast, understanding (in its direct form) is required to complete an explanation: it is ‘‘where explanation ends.’’ In other words, explanation depends on direct understanding: explanation cannot do without understanding, but understanding does not require explanation. In sum, the papers collected in this special issue investigate the relation between scientific understanding and explanation in various ways and present different viewpoints. Both Hindriks and Turner argue that in the social sciences understanding is possible independently of explanation. Moreover, according to Turner, social-scientific explanation must be grounded in understanding; without it remains incomplete. Gijsbers makes a case for the idea of understanding without explanation on a different, more general level: he argues that unification by means of classification provides understanding but no explanation. Such non-explanatory understanding can in principle be obtained in both natural and social sciences. While not denying that explanation and understanding may be intimately related, Gijsbers, Hindriks, and Turner regard understanding as a cognitive achievement with a life of its own. Strevens, by contrast, defends the Hempelian idea that scientific understanding is inherently associated with explanation. On his view, understanding cannot live without explanation, while explanation can perfectly well do without understanding. Thus, the authors arrive at diverging conclusions on how understanding and explanation relate to each other. Nevertheless, they take steps in the right direction. For a long time the marriage between explanation and understanding was taken for granted and left unanalyzed. The essays in this special issue are meant to change this unhappy situation and contribute to a deepening of our understanding of the relation. Do understanding and explanation need each other, or should they go their own way? In the interest of a healthy relationship, living apart together seems advisable, at least for the time being.
H.W. de Regt / Studies in History and Philosophy of Science 44 (2013) 505–509
Acknowledgements I thank the Lorentz Center (University of Leiden) and the Netherlands Institute for Advanced Study (NIAS, Wassenaar) for hosting, facilitating, and supporting the Lorentz Workshop Understanding and the Aims of Science (31 May–4 June 2010), where the papers were first presented. James McAllister is thanked for co-organizing the workshop and for helping with the start-up of this publication project, Hans Radder for his comments on an earlier version of this introductory essay, and the referees for reviewing the submitted papers. References Achinstein, P. (1983). The nature of explanation. New York: Oxford University Press. de Regt, H. W. (2006). Wesley Salmon’s complementarity thesis: Causalism and unificationism reconciled? International Studies in the Philosophy of Science, 20, 129–147. de Regt, H. W. (2009). The epistemic value of understanding. Philosophy of Science, 76(5), 585–597. de Regt, H. W., & Dieks, D. (2005). A contextual approach to scientific understanding. Synthese, 144(1), 137–170.
509
de Regt, H. W., Leonelli, S., & Eigner, K. (2009). Scientific understanding: Philosophical perspectives. Pittsburgh, PA: University of Pittsburgh Press. Gijsbers, V. (2007). Why unification is neither necessary nor sufficient for explanation. Philosophy of Science, 74, 481–500. Grimm, S. R. (2010). The goal of explanation. Studies in History and Philosophy of Science A, 41(4), 337–344. Hempel, C. G. (1965). Aspects of scientific explanation and other essays in the philosophy of science. New York: The Free Press. IPCC (2012). Climate change 2007 – The physical science basis, working group I contribution to the fourth assessment report of the IPCC. Cambridge: Cambridge University Press. Published online: