ABSTRACT: Economists have long been criticized for their use of highly idealized models. In Economics rules: Why economics works, when it fails, and how to tell the difference [Oxford: Oxford University Press, 2015] Dani Rodrik responds to this criticism by offering an account of models that emphasizes the diversity of models in economics. Rodrik’s account presents a rare opportunity for economists and philosophers of economics to engage in mutually beneficial exchange that could better our understanding of the power and limits of economics, and the rights and wrongs of the dismal science. The symposium on Rodrik’s Economics Rules is the first attempt to seize this opportunity.
Keywords: economics, philosophy of economics, criticism of economics, history of economics, Dani Rodrik, symposium
JEL Codes: B40, B41
Everyone is familiar with the (aesthetically) unpleasant walking-paths on public green fields. Usually, around these fields there are constructed paths for the service of the beloved citizens. However, citizens seem to deviate from these designed paths and take shortcuts passing through the green fields, through the zones they should not pass. The outcome of this behaviour is the death of the plants and the emergence of paths on these fields. Is there a good and acceptable explanation of why these walking-paths emerge? What kind of an explanation would be acceptable?
One scenario about the emergence of these paths may be the following. The first person to take a shortcut through the aforementioned field believes that his behaviour will do no harm to the green field and proceeds to take the shortcut. Obviously, he will in
fact have a negligible impact on the field. Subsequently, a second person, without being aware of the fact that he is the second person, takes the same shortcut with similar thoughts in mind. However, although the second person’s impact is still negligible, in time the damage on the plants accumulates. After some time, if some other people take that very same shortcut the damage will soon become visible. As a consequence, even if some earlier citizens did not intend the outcome of their behaviour, the damage to the plants will become visible; and hence the emergence of the path.
The plants may recover if everybody ceases to use the path. However, people generally continue taking shortcuts given the fact that they see the damage previously done by others. What are they thinking? Do they intend to bring about and maintain a visible path with no plants on it? Probably (and hopefully) not! Their reasoning is perhaps the following: ‘Even if I do not take the shortcut, some others will, thus the path will stay there anyway. Then, why should not I take the shortcut?’ So in this scenario, although individuals do foresee the outcome of their behaviour, they think that the creation of the path would be inevitable, given that everyone takes the shortcut. Moreover, if one particular individual is the only one taking the shortcut, the consequence of her action would be negligible. Thus, she takes the shortcut without intending to create such a nasty path. In this scenario the damage done to the plants has reinforced other people
to use that same path for it already exists. Thus, unless someone intervenes, the path is there to stay.
Would this scenario explain the emergence of these walking-paths? It sounds reasonable, but definitely not everyone is likely to accept this explanation. In fact, this was just one possible explanation. By introspection some of you may think that there may be other motivations behind taking these shortcuts. You may argue that people do not think about the consequences of their action at all when taking these shortcuts or you may think that these paths are intentionally created. For example, you may argue that one of those paths emerged due to a poorly planned city park which resulted in people intentionally taking a particular shortcut to show their dissatisfaction with the planning of this particular public space.
The above is yet another possible way to explain the emergence of these paths. More importantly, this explanation contradicts the previous general scenario. Thus one is tempted to ask: ‘unless some evidence is provided why should we believe in such speculations?’ If we would ask different people to explain this fact, we would get many different explanations. Many of these explanations would contain a story that makes the emergence of the path plausible. Hence, we would be left with many different (but not necessarily mutually exclusive) speculations or conjectures instead of ‘proper’ explanations. The fact that there are walking paths on public green fields is ostensibly simple to explain; however, it seems we are left only with conjectures.
Broadly speaking, conjectures and their explanatory characteristics are the subject matters of this book. It examines one particular type of explaining practice in social sciences, namely explaining the emergence of institutions (e.g., conventions and norms) and macro-social structures as unintended consequences of human action, from a methodological and philosophical perspective.
Explanations of ‘unintended consequences’ show numerous similarities with the above example of walking-paths on public green fields. The basic similarity however is that they seem to lack empirical content and as such they can be criticised as being simple conjectures with no explanatory value. This book illustrates the merits and demerits of such explanations by examining some of these attempts to explain institutions and macro-social structures as unintended consequences.
This is a book about ‘unintended consequences of human action’ and the mechanisms that bring about these consequences. It investigates the explanatory role of the models that characterise institutions and macro-social structures as unintended consequences of human action.
Many economists argue that certain institutions and/or social structures, such as money, language, rules of the road, fairness, segregated city patterns, and localisation are unintended consequences of human action. Similar ideas can be found in other disciplines, such as in philosophy of language (e.g., Lewis 1969), in political philosophy (e.g., Nozick 1974), in linguistics (e.g., Keller 1994) in philosophy of science (e.g., Hull 1988), in sociology (e.g., Merton 1936, Boudon 1982). The above list, which can definitely be extended, illustrates the importance of the problem of explaining unintended consequences in social sciences and in (political) philosophy. Popper (1962: 342) acknowledged the significance of unintended consequences for social sciences by arguing that the explanation of unintended consequences of human action is ‘the main task of theoretical social sciences.’ Yet unintended consequence is a vague concept and as such it may denote many different things. In this book we will be concerned with a subset of the set of possible unintended consequences; the one which is of paramount importance to economics in explaining institutions and macro-social structures. The rough description of this subset is as follows (see Mäki 1990b, and Chapter 2 & 5):
Individuals do not intend to bring about a social phenomenon (e.g., a social institution, or a macro-social structure).
The consequence of their action is a social phenomenon (i.e., an institution or a social structure)
One individual alone is not enough to bring about the ‘social’ consequence—that is, independent actions of similar (in the sense that they do not intend to bring about the consequence) agents are needed.
An explanation of unintentionally hurting your hand, or an explanation of the unintended consequences of a government tax plan does not fall under the above definition and hence are not examined in this book. The former is not examined because the consequence is not a social phenomenon (violates condition b—and c depending on the case); the latter is not examined because the intention is about a social institution (condition a is violated). Given our definition, ‘unintended consequence’ is a crucial component of the ‘theory of spontaneous order’, of Adam Smith’s ‘invisible hand’, of Carl Menger’s notion of ‘organic phenomena’ and of ‘invisible-hand explanations’. It lies at the core of many contemporary models of institutions and macro-social structures.
The theory of spontaneous order finds its origins in 18th century Scottish Thought and it is defined with its characterisation of the social order as ‘unintended consequence of countless individual actions’ (Hamowy 1987: 3). Adam Smith, the founder of modern economics, who was part of this tradition, presented a metaphorical statement of ‘spontaneous order’ with the ‘invisible hand’. Menger, on the other hand, presented a closely related account of spontaneously created social institutions where he considered them as being similar to ‘organic phenomena’. Many social scientists and philosophers followed Smith and Menger by trying to answer versions of their questions about institutions and macro-social structures. Their aim was to show how institutions and social structures could emerge (or persist) without any design. Generally it is believed that neoclassical economists followed Smith’s lead and tried to prove his insights. However, neoclassical economists’ approach is only one of the possible ways to interpret Smith’s insights. There are at least two different interpretations of the ‘invisible hand’: the one that stresses ‘processes’ and the other that emphasizes ‘end-states’ (see Chapter 5). Neoclassical economists’ approach is an end-state interpretation: The ‘invisible hand theorem’ in economics stresses the consequences (e.g., optimum allocation of resources), rather than the processes that bring about these consequences.
This book is mainly concerned with what may be called the process interpretation of the invisible hand. Under this interpretation the ‘invisible hand’ represents causal and structural relationships and processes that may bring about unintended social consequences. Explanations under this particular interpretation can be gathered under the notion of ‘invisible-hand explanations’. An invisible-hand explanation aims to show the process that brings about the unintended consequence. Rather than merely focusing on the properties of the end-state (e.g., equilibrium), it explicates the way in which the end-state may be reached (Nozick 1974, Ullmann-Margalit 1978). It is possible to find many examples of such process models in the contemporary literature. The most prominent examples are game-theoretic models of institutions that show how institutions may emerge (or persist) as an unintended consequence of human action (e.g., Bicchieri 1993, Sugden 1986, Ullmann-Margalit 1977, Young 1998 etc.). Another area where unintended consequences are important is the emerging field of agent based computational economics (e.g., Axelrod 1997, Axtell et al. 1999, Epstein and Axtell 1996, Marimon, McGrattan et al. 1990 etc.). The pioneers of the game-theoretic literature acknowledge David Hume, Adam Smith and Carl Menger as their forefathers (see Lewis 1969, Sugden 1986, Ullmann-Margalit 1977, Young 1998) and similarly agent based computational economists generally acknowledge their intellectual debts to Adam Smith and Thomas Schelling (e.g., see Epstein and Axtell 1996, Tesfatsion 2002).
Carl Menger’s (1892a) story of the emergence of a medium of exchange, Thomas Schelling’s (1969, 1971, 1978) models of residential segregation, Peyton H. Young’s (1993a, 1996, 1998) model of emergence of the rules of the road and Joshua Epstein’s and Robert Axtell’s (1996) ‘Sugarscape’ (where they grow artificial societies from the bottom up) are well known examples of such models. These examples range from verbal models (or stories) to formal game theoretic and computational models. Despite the differences in their methods and research tools there is an important similarity between them. Each shows how institutions and macro-social structures may emerge (or persist) as an unintended consequence of the (inter)actions of individuals. In order to do this, the authors conjecture (in the latter case with the help of computers) about the conditions under which individual actions may lead to the social phenomena in question. The common feature of these examples is that the observed social phenomenon (i.e., institution or macro-social structure) is ‘produced’ within the model-world by conjecturing about the initial conditions (e.g., environmental conditions, characteristics of the agents etc.) that may bring about the social phenomenon in question as an unintended consequence of the interactions of the agents. Moreover, these models are typically ahistorical in the sense that historical facts about the social phenomenon in question do not seem to play any role in these models. They are general and thus they are supposed to be applicable to all instances of the social phenomenon in question in different times and places. These models illustrate the possible ways in which certain mechanisms may interact (or may have interacted) to produce the types of institutions or macro-social structures in question.
More strikingly, some of these models seem to challenge the common sense and the historical knowledge about these social phenomena. For example, while many believe that money is a matter of design and was issued by central authorities in the past, Menger argues that it was brought about by the (inter)actions of individuals who were pursuing their self-interests without the intention to bring about a commonly acceptable medium of exchange. Schelling, on the other hand, shows that if individuals cannot tolerate living as an extreme minority in their neighbourhood, then residential segregation cannot be avoided even if they are happy in a mixed neighbourhood. Of course this seems to go against our belief that strong discriminatory preferences (e.g., racism) and economic factors (e.g., wealth differences among ethnic groups) are the main causes of residential segregation. A more recent example is Young’s model of the rules of the road. He shows that the rules of the road may emerge with the accumulation of the precedent as an unintended consequence of the (inter)actions of the individuals. This model also goes against the belief that the rule that specifies on which side of the road one should drive was designed and imposed by central authorities like other traffic rules. Finally, Epstein and Axtell show how under certain conditions fundamental social structures and group behaviours (e.g., institutions, segregation, cooperation) could emerge from the micro level. In this example, social phenomena are quite literally grown by the authors.
All of the aforementioned examples pose difficult questions for social scientists and philosophers. How could these models explain anything if they are simply speculations about the initial conditions under which social phenomena may be brought about as unintended consequences? In other words, we understand that these authors are able to ‘produce’ a certain social phenomenon in their model world as an unintended consequence of the interactions of model agents. However, given that these models are so abstract, ahistorical and speculative, how could they be used to explain something about the real world?
The philosophical and methodological challenges posed by these models created many debates in related areas. These debates constitute a significant part of the controversies about the role of abstract modelling in social sciences. The related question here is whether we can learn anything about the real world by studying highly abstract models. This is one of the basic questions of philosophy of science. The usual defence of scientific models is the claim that they isolate the relevant parts of the real world and that such realistic representations of the real world give a close to true account of the phenomenon in question when other things are absent or constant. Some economists also use the argument from realistic representation in defence of their models. For example, Young (1998: 10) argues that the assumptions of his models ‘represent a fairly accurate picture of reality.’
However, the main criticism to these models is that they ignore the relevant facts, such as the history of the social phenomenon in question—and therefore they do not realistically represent the relevant parts of the real world. For example Menger’s ‘the origin of money’ does not take into account the way in which money was issued and introduced in history. Moreover, Schelling’s model of segregation seems to sidestep two of the most important facts about segregation—the presence of strong discriminatory preferences and the role of economic factors. Thus the argument concerning realistic representation either has to demonstrate why history is irrelevant, or to show the complementarity between these models and history.
As mentioned above, these models start with the problem (e.g., that there is residential segregation) and try to produce the conditions under which this problem may emerge as an unintended consequence of human (inter)action. This methodology invites criticism for the following two reasons. Firstly, it seems to be one sided, for it tries to construct a model that shows something that the author wishes to see (e.g., residential segregation as an unintended consequence). Secondly, it may be argued that if one devotes enough time and energy it should be possible to construct a reasonable model that is able to show whatever we wish.
Given the focus of this book the relevant place to start seeking solutions to these problems is the literature on ‘invisible-hand explanations.’ It is argued in this literature that invisible-hand explanations are valuable independently from their truth for they explicate the process that may have brought about the social phenomenon at hand (Ullmann-Margalit 1978). This suggests that these models are valuable even if they are false, or even if they do not get the facts right. It is argued that explication of a hypothetical process that is sufficient to bring about the social phenomenon in question is valuable for its own sake. However, it is not explained why this explication would be valuable, or in what sense it would help us understand the real world. Simply this argument does not help us much unless it is explicated! This is merely a statement of the author’s intuition about the value of these ‘explanations’. Economists use these models because they believe that they are valuable. For example, Robert Sugden (2000) argues that the reason we believe that these models are conveying a true message about the real world is that we find them ‘credible’—by way of examining Schelling’s segregation model. He argues that these models are credible like a good story or a novel. Sugden’s basic argument boils down to the statement that we think these models are valuable because we find them plausible. This argument cannot demonstrate the value of these models unless it explains why they are plausible and in what sense plausibility of a conjectural process sheds light on the real world.
Another type of justification comes from computer simulations. It is argued that artificial environments (models, computer models) are used to gain insights about the social phenomenon in question (e.g., see Gilbert and Doran 1994a, Liebrand et al. 1998) or that models and computer simulations are like experiments where we test our ideas (e.g., see Drogoul and Ferber 1994) or that they are similar to thought experiments (e.g., Liebrand 1998, Liebrand et al. 1998). Briefly it is argued that models and simulations help us in finding out the necessary conditions under which certain results (e.g., segregation) are brought about (within the computer model) and in easily exploring the properties of these model environments. In this account these models are not for explanation but for exploration. However, this does not answer our question about moving from the model world to the real world. Specifically, a satisfactory defence of these models would have to tell us how to translate the results of the model in order to interpret the real word.
The discussions about the interpretation of game theory are also relevant in this respect. As mentioned above, some economists like Young use the argument from realistic representation to justify game-theoretic models. Yet not every game theorist would agree with this. One of the most prominent scholars of this field, Robert Aumann (1985) (also see van Damme 1998) argues that realisticness of the models does not matter that much. According to him, the conclusions are much more important: If the model is applicable to many situations and is productive, then it is a good model. He also argues that game theory (and other sciences—in his opinion) ‘is not a quest for truth, but a quest for understanding.’ He says, ‘science makes sense of what we see, but it is not what is “really” there’ (van Damme 1998: 181, 182). Aumann basically argues that game-theoretical models help us in putting together what we observe in a coherent framework, that they help us in fitting things together. He also argues that they lead to prediction and control. However, if we accept Aumann’s interpretation of game theory (and science) we are still faced with the following questions: Firstly, if the models of institutions and macro-social structures do not represent the reality how could they lead to prediction and control, and most importantly to understanding? Secondly, Aumann emphasises the productiveness and applicability of the models. Yet the current state of the modelling of institutions and macro-social structures (as unintended consequences) cannot be considered to have many real world applications or satisfactory predictive power. Should we then conclude that these models are not valuable?
It is the argument of this book that all of the interpretations expressed above convey justifiable intuitions about these models. That is, ‘realisticness’, ‘explication’, ‘credibility’, ‘exploration’, and ‘fitting things together’ are all parts of a framework that would help us in making sense of these models. However, there is no existing framework where these things are presented coherently and satisfactorily. It is the main task of this book to develop such a framework and to use it to gain new insights into the contemporary literature that characterises institutions and macro-social structures as unintended consequences of human action.
PLAN AND SUMMARY OF THE BOOK
To be able to develop such a framework one has to understand what these models really accomplish. The most obvious way to do this is to carefully examine these models and their methodology. But before doing this, a clarification of the very idea of ‘unintended consequences’ is needed. The Second Chapter analyses and explicates the concept of unintended consequences to prevent misunderstandings that may be caused by its vagueness. In particular, the subset of the set of possible unintended consequences, which is relevant for understanding the models of institutions and macro-social structures as unintended consequences, is specified.
In Chapters Three and Four, the most prominent examples of such models, Menger’s ‘origin of money’ and Schelling’s ‘checkerboard model of segregation’ are examined. It appears they are natural candidates for several reasons. First of all, these models are paradigmatic examples of ‘explaining unintended consequences of human action’ and of invisible-hand explanations. Contemporary authors consider these models as conveying the key insights about their subject matter and about the way in which related issues should be handled. Their models are the predecessors of contemporary research in modelling institutions and macro-social structures as unintended consequences of human (inter)action. Menger is considered to be one of the founding fathers of the theoretical approach to institutions as opposed to the historical approach (e.g., see Rutherford 1994, Schotter 1981). Schelling’s model is one of the main predecessors of agent-based computer models (e.g., see Epstein and Axtell 1996, Blume and Durlauf 2001, Pancs and Vriend 2003, Rosser 2000, and Casti 1989) and it is considered to be the paradigmatic example of explaining with mechanisms in social sciences (e.g., see Hedström and Sedberg 1998). Briefly, since their models play an important role in the history of ‘explaining unintended consequences of human action’ understanding Menger’s and Schelling’s models should shed light on the related areas of contemporary research.
Another good reason to start our examination with these models is the fact that both Menger and Schelling are explicit about their methodology. In their work, they explain why they prefer the type of research they are engaged in. Moreover, in the literature there is a considerable amount of philosophical discussion about their methodology. As previously mentioned, their works are predominantly considered to be paradigmatic examples of invisible-hand type of ‘individualistic’ explanations (e.g., see Nozick 1974, Pettit 1996, Rosenberg 1995, Rutherford 1994, Ullmann-Margalit 1977). It is also common to examine the recent game-theoretical models of institutions alongside invisible-hand explanations (e.g., see Langlois 1986bc, Mäki 1993, Rosenberg 1994, Rutherford 1995, Vanberg 1994). It has also been stated that the authors of these models (including the authors of the computational models) consider themselves as following the invisible-hand tradition, or providing the mechanisms behind the invisible hand. For these reasons there is a considerable amount of resources that may help us in our quest. Thus we are more likely to find hints about the nature of similar models by starting our examination from Menger and Schelling’s models and their relation to the invisible hand. In addition, this choice makes it easier to see the common misunderstandings about ‘explaining unintended consequences of human action’ for the literature on invisible hand type of ‘individualistic’ models is abound with controversies. The Fifth Chapter undertakes the task of examining ‘invisible-hand explanations’ in light of the chapters on unintended consequences, and Menger and Schelling’s models. This examination sheds light on the nature of invisible-hand explanations. Particularly, an important misunderstanding about the relation between ‘unintended consequences’ and the ‘invisible hand’ is removed. By way of removing this misunderstanding the chapter prepares the ground for examining contemporary examples of invisible-hand explanations.
Menger and Schelling’s models and insights were reconsidered and remodelled by contemporary authors. For this reason there is an explicit link between these models and the contemporary literature we wish to understand. This gives us a chance to evaluate the progress of this ‘research program’. For example, some of the papers directly related to Menger’s account of the medium of exchange can be listed as follows: Duffy and Ochs (1999), Gintis (1997), Kiyotaki and Wright (1989), Marimon, McGrattan et al. (1990), Schotter (1981), Selgin and Klein (2000), Townsend (1980), Young (1998). Some of the follow-ups to Schelling’s segregation model are the following: Clark (1991), Epstein and Axtell (1996), Sander et. al. (2001), Young (2001), and Zhang (2000, 2004ab). By examining these reconsiderations we may indeed see whether there is any progress or whether contemporary tools (e.g., game theory and computer modelling) improve the way in which we understand and explain the origin of money and segregation. Accordingly, the Sixth Chapter examines the more recent models of the emergence of money in detail, while recent reconsiderations ‘residential segregation’ are used as examples in Chapter Seven.
Particularly, in Chapter Six it is argued that we should not evaluate models that characterise macro-social phenomena as unintended consequences in isolation from other related models of the same phenomenon. In order to substantiate this proposition, recent reconsiderations of Menger’s explanation of the origin of money are examined. The chapter shows how Menger’s intuitions are further explored in the modern literature in various ways. It is argued that these recent models test the logical soundness of Menger’s arguments but do not bring us any closer to the real world. Recent models of the origin of money do not introduce new mechanisms but test the plausibility of the mechanisms that were suggested by Menger. While these models increase the plausibility of the idea that media of exchange may be brought about unintendedly, it is argued here that the idea that fiat money may be considered as an unintended consequence of human action does not appear to have a firm basis. Moreover, the chapter examines and demonstrates the relation among these models. This examination supports the thesis that different models have different functions and different models of the same phenomenon may be considered as forming a loose framework for explaining particular instantiations of it.
Chapter Seven explores the philosophical literature on models and explanation to provide a firmer basis for the arguments of the previous chapters. In particular, firstly, the concept of partial potential explanations is explicated. Secondly, it is argued that models help us explain by way of providing a proper way to conceptualise the phenomenon under question. Yet this further implies that the relationship between the model world and the real world is rather complex. Thirdly, it examines this complex relationship by way of discussing the related philosophical literature in light of the previous chapters. Fourthly, it is argued that similarity between models that are examined in this book and the real world amounts to the existence of certain (known) tendencies (individual mechanisms) in the model world. For this reason these models may be interpreted as revealing the possible ways in which these tendencies may interact, even if some of the assumptions of these models do not hold. Fifthly, the chapter emphasises the importance of exploration. Particularly, it shows how one may gain confidence about the implications of an existing model by way of further exploring its premises and results. To do this the chapter discusses reconsiderations of the checkerboard model. Finally, the chapter fortifies the idea that no model of this sort should be evaluated in isolation from other related models.
Chapter Eight examines the modern game theoretical models of conventions in light of the ideas developed in previous chapters. These models may be considered as attempts to provide a general theory of the emergence of conventions. The chapter reviews some of the existing game-theoretic literature on conventions and shows that existent conventions and norms, particular institutions and history are crucial for explaining the emergence of conventions. Six arguments are put forth in the chapter: (i) Static models of coordination (and convention) are concerned with examining the conditions under which certain outcomes are plausible, rather than explaining why and how such outcomes are brought about. Hence such models are in line with the end-state interpretation of the invisible hand. (ii) Dynamic models of coordination provide partial potential (theoretical) explanations of the emergence of coordination and conventions. Hence such models are in line with the process interpretation of the invisible hand. (iii) None of these models rule out the possibility that coordination and conventions may be brought about intentionally. Rather they examine whether successful coordination and conventions may emerge as unintended consequences of human action. The interpretation of these models as providing partial potential explanations is well in line with this remark. (iv) Explaining particular cases (e.g., explaining the emergence of a particular convention) necessitates empirical research. Nevertheless, general models of coordination and conventions need not be empirical or historical. (v) The collection of different models of coordination and conventions may be considered as providing a general framework for empirical research and providing singular explanations. (vi) Game-theoretic models in general may be interpreted as providing a framework for analysis, rather than providing ultimate explanations concerning social phenomena and individual behaviour. The Final Chapter concludes the book with questions for further research.
The Invisible Hand in Economics How Economists Explain Unintended Social Consequences INEM Advances in Economic Methodology London: Routledge, 2008.
This is a book about one of the most controversial concepts in economics: the invisible hand. The author explores the unintended social consequences implied by the invisible hand and discusses the mechanisms that bring about these consequences.
The book questions, examines and explicates the strengths and weaknesses of invisible-hand type of explanations of emergence of institutions and macro-social structures, from a methodological and philosophical perspective. Aydinonat analyses paradigmatic examples of invisible-hand explanations such as Carl Menger’s ‘Origin of Money’ and Thomas Schelling’s famous checkerboard model of residential segregation in relation to contemporary models of emergence of money and segregation. Based on this analysis, he provides a fresh look at the philosophical literature on models and explanation and develops a philosophical framework for interpreting invisible-hand type of explanations in economics and elsewhere. Finally, the author applies this framework to recent game theoretic models of institutions and outlines the way in which they should be evaluated.
Covering areas such as History, Philosophy of Economics and Game Theory, this book will appeal to philosophers of social science and historians of economic thought as well as to practicing economists.
Conjectural models aim at devising the initial conditions required for individual actions to generate a given social phenomenon as unintended consequence. Social scientists make frequent use of this modeling technique. Indeed the list of those who have applied it – from Smith to Menger, from Schelling to Lewis – reads likely a veritable “who’s who” of the last 250 years of social sciences. Yet the question of how these purely speculative models may actually enjoy any explanatory power with respect to real world phenomena has only rarely been tackled. Aydinonat’s outstanding work fills this gap by thoroughly investigating the philosophical and methodological challenges posed by conjectural models and by developing a coherent and persuasive framework to account for the role of abstract theorizing in the social sciences. The book is a candidate to become compulsory reading for methodologists and philosophers of science, as well as for those economists who take seriously the issue of their models’ epistemological foundations.
by Robert Sugden:
There is a long tradition in the social sciences, going back to Adam Smith, of explaining social phenomena as the unintended consequences of human actions. In this illuminating book, Aydinonat investigates the structure of such explanations and the nature of the claims that can legitimately be derived from them. In the process, he analyses some of the classic ideas in social theory – Smith’s invisible hand, Carl Menger’s explanation of the emergence of money, Thomas Schelling’s analysis of racial segregation, and David Lewis’s theory of convention – with acuity and subtlety. This is a significant contribution to the philosophy of social science which will also engage the interest of reflective economic theorists.
by Edna Ullmann-Margalit:
The book’s choice of the topic with which economists and philosophers could start engaging each other cannot be improved on. The notion of the invisible hand, and the type of explanations it gives rise to, of social patterns of behavior as unintended consequences of individual actions and interactions, are just right for the cross-fertilization between a variety of philosophical ﬁelds, prominently including the philosophy of science, on one side, and economic theory, prominently including game theory, on the other. Moreover, the experience of reading this book leaves the reader feeling that the choice of author for this undertaking can hardly be improved on either.
Trained both in economics and in philosophy, Emrah Aydinonat has formal and technical skills as well as a historical sensibility and a keen intellectual curiosity, and he has the tenacity to go on digging for gem-stones where previous visitors to the same terrain seem content with surface pebbles. Setting himself the task of developing a framework capable of making sense of the marketplace of extant models, and then to use this framework to ‘gain new insights into the contemporary literature that characterizes institutions and macro-social structures as unintended consequences of human action’ (p. 7), he has produced a book that is pleasingly disciplined and well organized.”
“Aydinonat’s book provides a historical context in which the notion of the invisible hand emerged, and analyzes the concepts and the distinctions behind this notion at such a high resolution that no scholar is likely to revisit this territory ever again. Any and every future discussion of the invisible hand – and there are sure to be such – will from now on make the obligatory reference to this book and simply take off from it. (Read the review)
by Mark Blaug
This is a splendid book about a controversial concept in economics, the notion that there may be unintended benevolent social consequences of actions undertaken by individuals for entirely private reasons and that these consequences are not merely benevolent but are capable of producing an order that appears to be designed although it is actually the product of spontaneous action. (Read the review)
by Wade Hands:
In summary, I found Aydinonat’s book to be a very important contribution to the literature. This is not to say that I would not quibble about specific details of his argument – but it does provide a very useful, and quite coherent, framework for thinking about the explanatory power and adequacy of invisible hand-type explanations. Such explanations are so pervasive in economics – for some they define economics – and yet we previously lacked any coherent framework for situating them within the broader context of scientific explanations in general. Aydinonat has provided us with a badly needed framework for investigating these issues. The Invisible Hand in Economics will not be the last word on invisible hand explanations, but it will become an obligatory reference point for any future research on the subject, and I recommend it to anyone who would like to better understand this very important class of models. (Read the review)
by Warren Samuels:
This study by a sensitive and imaginative intellect is a substantive contribution to the literature developing the meaning of the concept of ‘‘the invisible hand’’ while simultaneously attempting to establish how interpretation can be structured to convey ‘‘understanding’’ albeit not ‘‘truth.’’ (Read the review).
by Anna Alexandrova:
Where do social institutions and phenomena come from? A venerable tradition in economics seeks to explain some of these institutions and phenomena, for example, money, traffic rules, racial segregation and many others, using a concept of invisible hand. Such explanations show a phenomenon to be an unintended outcome of a multitude of actions and interactions of individual persons. In a book based on his doctoral dissertation, Emrah Aydinonat seeks to a) give an account of what sort of social phenomena are susceptible to this sort of explanation, b) evaluate the success of some of the most famous explanations of this type, and along the way, c) draw lessons for philosophical accounts of formal models in economics. In many ways, this book represents philosophy of economics at its finest. It is impeccably informed on the present state of economics, sensitive to the history of the discipline and full of interesting and thoughtful philosophical analysis. A significant problem, however, is that the central notion of the paper – partial potential explanation – does not receive an appropriate articulation. After presenting Aydinonat’s views, I explain the problems and why they matter. (Read the review)
ABSTRACT. This paper discusses the epistemic import of highly abstract and simplified theoretical models using Thomas Schelling’s checkerboard model as an example. We argue that the epistemic contribution of theoretical models can be better understood in the context of a cluster of models relevant to the explanatory task at hand. The central claim of the paper is that theoretical models make better sense in the context of a menu of possible explanations. In order to justify this claim, we introduce a distinction between causal scenarios and causal mechanism schemes. These conceptual tools help us to articulate the basis for modelers’ intuitive confidence that their models make an important epistemic contribution. By focusing on the role of the menu of possible explanations in the evaluation of explanatory hypotheses, it is possible to understand how a causal mechanism scheme can improve our explanatory understanding even in cases where it does not describe the actual cause of a particular phenomenon.
Citation: Ylikoski, Petri & N. Emrah Aydinonat. 2014. “The Diversity of Models as a Means to Better Explanations in Economics.” Journal of Economic Methodology, 21 (1), 19-36. https://doi.org/10.1080/1350178X.2014.886470
ABSTRACT. In Economics Rules, Rodrik [(2015). Economics rules: Why economics works, when it fails, and how to tell the difference. Oxford: Oxford University Press] argues that what makes economics powerful despite the limitations of each and every model is its diversity of models. Rodrik suggests that the diversity of models in economics improves its explanatory capacities, but he does not fully explain how. I offer a clearer picture of how models relate to explanations of particular economic facts or events, and suggest that the diversity of models is a means to better economic explanations.
KEYWORDS: Theoretical models, explanation, diversity of models, how-possibly reasoning, functions of models
Imagine a first-year economics student. After attending six lectures in introductory economics, and carefully studying the first six chapters of his economics textbook, s/he gets comfortable with the basic supply-demand model. Bedazzled by the potential uses of this simple model and explanatory power of economics in general (looking at the covers of economics made fun books convinces her/him about this), s/he starts thinking that the supply-demand model is the only thing that s/he needs to know. As a firm believer of market solutions to everything, s/he quits school in order to give it back to you, the people. S/he becomes a politician (or adviser, author, columnist, the president…) and starts applying what s/he learned from the textbook to real-world problems. Because s/he skipped all other courses, s/he does not have any idea about how to conduct research on these important societal problems. So s/he bases all of his policy decisions (or suggestions) on the basic supply-demand model and a little bit of armchair reasoning. James Kwak’s book, Economism, is a critique of this student’s abuse of basic economics.
More properly, Economism is a book on the dangers of applying simplistic economic models to complex real-world problems. According to Kwak, economism is the act of trying to explain all social phenomena and to solve all societal problems with basic economics.
“[Economism] rests on the premise that people, companies, and markets behave according to the abstract, two-dimensional illustrations of an Economics 101 textbook, even though assumptions behind these diagrams virtually never hold in the real world.” (Chp.1)
You might ask: But who does that? Is there really anyone out there who acts like a university dropout president (politician, adviser, author, columnist…)? Kwak’s book provides enough evidence to show that economism is a real problem. And if you think about it, you might find your own examples of economism. Think about those politicians, columnists, experts, and journalists who talk about taxes, minimum wages, regulation, inflation, healthcare etc. Think about how TV and radio programs, podcasts, blogposts, tweets, etc. help an oversimplified supply-demand logic to reproduce and invade people’s brains. And think about how easy it is for anyone to have an illusion of understanding economics. If you could Google it, you could think that you know it! Search for tax policy, drug policy, minimum wage policy, or any other thing you like. You’ll get a quick answer and a fix for your problem. Anyone who is willing to learn some economics but does not have the time to do it properly can be infected with economism quite quickly. So Kwak’s attempt to warn us concerning the dangers of economism is a valuable endeavor.
Of course, Kwak is not the first person to warn us against the abuse of basic economics. Noah Smith, for example, wrote about economism in 2016. He called it 101ism. See for example, Most of What You Learned in Econ 101 Is Wrong, and 101ism. And here is something from Paul Krugman: 101 Boosterism. Last year, Dani Rodrik also warned us against misuses of economic models in his Economics Rules. Also note that there is a huge literature in philosophy of economics that discusses the limits of idealized and abstract models in economics. Given this background one expects a lot from a book length treatment of economism, or 101ism.
My expectations were very high. This is probably why I am disappointed. I knew in advance that in the book Kwak would be discussing how economism misleads us concerning issues such as the minimum wage, tax policy, and financial regulation. So I expected a detailed and careful discussion of these topics. Something that would go beyond the blog posts and columns cited above. Moreover, I really wanted to learn about the origins of economism. I wanted to learn who to blame, and why. On top of this, there was a lot of buzz on my twitter feed which also raised my expectations. I did not expect Kwak to dive into philosophy of science, but I was expecting that he would have some serious discussion of the limits and merits of simple, abstract, idealized models. At least I was expecting Kwak to go beyond just reminding us that economic models are unrealistic, and that they employ simplifying assumptions.
Even though Kwak uses considerable amount of space and several supply and demand graphs to demonstrate the possible ways in which that Econ 101 models may mislead us, he does not show the reader how one should really think about the issues discussed in the book. His argument basically boils down to the following claim: Econ 101 thinking is erroneous because the world is more complex than the basic model, and the empirical evidence concerning the matter is mixed. For example, Kwak (in Chp. 9) summarizes economism’s claim concerning labor markets as follows: “The minimum wage causes unemployment and harms poor people”. And here is how he summarizes how things are in reality: “The minimum wage (around current levels) has little impact on unemployment and reduces poverty”. Or, he summarizes economism’s claim concerning financial markets as follows: “People only buy financial products that are good for them”. And he argues that the more likely reality is “many people make poor choices about complex products such as Option ARMs”. Fair enough. But how should one avoid economism and think about these issues? Does Kwak have an answer to this question?
First note that Kwak does not argue that economics is useless or that economists should abandon their beloved simple models. He argues that
“The answer to economism is not to reject economics altogether. Rather, the immediate antidote to economism’s simplistic model of reality is more and better economic analysis, which can help identify the fundamental drivers of social phenomena or select the most effective solutions to difficulty problems” (Chp.9)
“Recognizing that economics does not provide a single simple answer to all questions is a crucial step in throwing off the blinders of economism” (Chp.9).
So Kwak seems to think that economic models help us understand the world. But he does not tell the reader how. The world is complex. All economic models are similar to the basic supply-demand model in that they simplify and employ unrealistic assumptions. Kwak does not help us in finding our way from simple models to more complex reality. If we would like to avoid economism, how should we approach the subject matter? What is the appropriate way to use economic models? Not clear! Kwak does not really attempt to answer these questions. We learn that we should be careful about the dangers of economism, and that is about it.
What about the origin and sources of economism? Kwak has a whole chapter on that. He makes some strong claims, such as the following:
“For a worldview like economism to take root and grow, it must serve a significant social group.” (Chp.3)
“[Economism] matters because it is one important vehicle that interests groups have used to pursue their objectives during the past half century.” (Chp.3)
“Economism exists because people organizations saw how they could use economic principles to their advantage.” (Chp.3)
“Today, economism reflects the preferences and interests of the very rich more than those of ordinary citizens” (Chp.9)
“The great achievement of economism has been to repackage a political ideology [market fundamentalism or neoliberalism] as a lightweight, easy-to-use, seemingly neutral framework for seeing the world.” (Chp.9)
Basic argument here is that economism benefits the wealthy, thus it must have been intentionally promoted by them. Unfortunately, Kwak does not provide enough evidence that these and other related claims concerning the origins of economism are right. The evidence he provides is basically about some connections between economists, institutions and people with money who funded some of these people and institutions. This lays down some of the connections, but it is not enough. Maybe it is impossible to provide a convincing account of the origin of economism in one chapter, but I was supposing that this was one of this book’s promises. So I was disappointed. To be fair, Kwak cites his resources. In order to get a better sense of the development of economism (especially in USA) one could read: The Idea Brokers (James Smith), The Power of Ideas (Lea Edwards), Building Chicago Economics (eds. Robert Van Horn, Philip Mirowski, and Thomas A. Stapleford), The Road from Mont Pèlerin: The Making of the Neoliberal Thought Collective (eds. Philip Mirowski and Dieter Plehwe), and other works cited by James Kwak.
After reading the book, we learn that economism is bad. Also, we are provided with a list of names and institutions that we could blame. I’ll only mention the names of the economists that pop up: Ludwig von Mises, Friedrich von Hayek (Nobel Prize 1974), Milton Friedman (Nobel Prize 1976), Gary Becker (Nobel Prize 1992), George Stigler (Nobel Prize 1982), and Richard Posner. Unfortunately, Kwak does not discuss the actual contributions of these economists to research. I cannot help thinking that maybe Kwak also got trapped by the simplistic thinking that he criticizes. Remember, he wished to argue that real economics is not like simplistic Econ 101, and that actual research in economics is superior to simplistic Econ 101 thinking. Could it be that the actual contributions of these economists are much more sophisticated and important than they appear in Kwak’s book? Let me just remind you that the list contains four Nobel laureates.
So what is my verdict? I enjoyed reading the book. It introduces the reader to the debates about minimum wages, tax policy, health policy, and financial regulation. Also, the chapter on the origins of economism could be considered as a good first reading on the topic. Nevertheless, I was disappointed because I was expecting much more from the book. So I’ll recommend the book with just one warning: If you would like to have a better understanding of how economists think and how to avoid economism and all that, this book will not help you much. If you are going to read this book, also read Dani Rodrik’s Economics Rules (see my review here). Dani Rodrik provides a much more sophisticated (and accessible) account of economic models and guidelines for using them appropriately. You could also supplement this book with other popular books. For example, you could read Ha-Joon Chang’s Economics: The User’s Guide, which champions a pluralistic approach to economic issues.
If you are wondering about the remedy for economism, remember the economics student who got infected because s/he quit learning economics too early. The first and most important remedy for economism is to keep on studying economics. A good economics education will teach you that if you try to apply a model without taking into account the specifics of the particular real-world problem you are dealing with, you are very likely to misunderstand the problem and its solution. After all, a good Econ 101 is the best cure for 101ism.  Naturally, I would also add some philosophy of economics to the recipe.
 Kwak also list the following institutions: Volker Foundation, Mont Pelerin Society, Foundation for Economic Education (FEE), The American Enterprise Institute, The Heritage Foundation, The Cato Institute, and The Manhattan Institute. Moreover, Kwak points out that authors like Henry Hazlitt and Jude Wanniski helped the spread of economism.
“Paying more attention to topics such as economic history, institutions, behavioral economics, common market failures such as asymmetric information, and empirical methods could help dilute the intellectual hegemony of the competitive market model.” (Chp.9)
But, students of economics learn about most of these topics. Also one of the first things that one learns in economics courses is that assumptions matter. True, there could be more emphasis on institutions, economic history, history of economics thought, and economic methodology. There is much room for improvement in economics education. But this does not justify the now widespread belief that economics education is harmful. I am almost sure that James Kwak would not agree with such a statement, but his book might contribute to this belief.
If you do not have much time, here is the main message of this review: Economics Rules is an excellent book; a must read for economists, philosophers of economics, and policy makers, and of course for economics students. And if you consider yourself as a critical economist, a heterodox economist, or a social scientist who is critical of the way in which economists work, behave, etc., the book has a lot to offer to you too (probably a lot to disagree about, but also a new perspective on economic models). While Dani Rodrik defends economics against popular lines of criticism; he also presents his own critique.
If you have more time, please read on.
[If you prefer a PDF version, it is available @Research Gate ]
Economics Rules is a book on the nature of economics and economics models. It defends economics against main lines of criticism. It argues that what makes economics powerful is its diversity of abstract and unrealistic models—but this is not a Friedman 1953 type of defense of unrealistic assumptions, as you’ll soon see.
In Economics Rules, Rodrik tries to show that critics have been criticizing economics for the wrong reasons. Economists, on the other hand, were right in defending economics, but they (well, at least most of them) have been doing it all wrong. In order to make his case, Rodrik presents an alternative account of economic models. He argues that this alternative account will provide economists “a better story about the kind of science they practice” (p. ix)—a story that will render most popular lines of criticism useless. As Rodrik puts it Economics Rules explains “why economics sometimes gets it right and sometimes doesn’t” (p. 4) and defends the core of economics—”the role that economic models play in creating knowledge”—but criticizes “the manner in which economists often practice their craft and (mis)use their models” (p. 6).
Rodrik argues that abstract theoretical models are useful, but they are also limited by the assumptions they make. Economic models do not provide us with fundamental economic laws. Their results are dependent on the conditions described by their assumptions. Thus one should be careful in generalizing a model’s results. A common mistake in economics, he argues, is to mistake a model, with the model. In fact, same applies to critics. Popular lines of criticism against economics models also mistake a model, with the model. Critics argue that economic models are too abstract and too detached from the world by way of comparing a model with the real world. However, Rodrik argues that this criticism misses the point because it ignores the diversity of models in economics. Economists’ toolbox is filled with a variety of models, and which (combination) of these models are relevant depends on the case at hand. Thus, he argues, by focusing on one model at a time many critics fail to see what makes economics so powerful.
Economics Rules is filled with interesting and thought provoking ideas and examples from economics, but (I think) its main contribution is Rodrik’s alternative account of economic models. For this reason, in what follows I will only discuss Rodrik’s account of economic models.
Unrealisticness of Economic Models
In the aftermath of the 2008 economic crisis, many economists raised concerns about the way in which economics is practiced. Probably, everyone remembers Paul Krugman’s article in The New York Times Magazine. He argued:
“[…] the economics profession went astray because economists, as a group, mistook beauty, clad in impressive-looking mathematics, for truth. […] When it comes to the all-too-human problem of recessions and depressions, economists need to abandon the neat but wrong solution of assuming that everyone is rational and markets work perfectly. The vision that emerges as the profession rethinks its foundations may not be all that clear; it certainly won’t be neat; but we can hope that it will have the virtue of being at least partly right.” (Paul Krugman, in How Did Economists Get It So Wrong?)
2008 crisis is one reason why economists have become worried about the assumptions they make, but it is not the only reason. Developments in behavioural-experimental economics and neuroeconomics were also pushing economists in a direction that many of them would prefer not going: discussing philosophical issues concerning the nature and scope of economics. Nevertheless, the challenge was powerful and some economists tried to defend their field against criticism coming from these new research areas (e.g., see Gul and Pesendorfer’s The Case for Mindless Economics). For example, the debate concerning neuroeconomics produced at least two journal special issues (1, 2) and one book entitled The Foundations of Positive and Normative Economics: A Handbook (Chaplin and Schotter 2008). (For the story of behaviroal economics and the challenges it presented, I recommend Richard Thaler’s excellent book: Misbehaving: The Making of Behavioral Economics). And there was the students: Revolting against the way in which economics was taught; demanding a more pluralistic economics education and more real world content. This started with the post-autistic economics movement (later changed its name) and after the economic crisis student revolt spread out. Post Crash Economics Society, for example, demanded that economics education should reflect the post-crash world. Now there is a global network for students, called Rethinking Economics who are working to transform economics education for the better
Although debates concerning the explanatory power of economics became popular in the last decade—especially after the 2008 crisis—such debates were not foreign to economists. History of economics is full of debates like this. Take for example the marginalism controversy in 1940s (for a good review, see the 2nd chapter of Jack Vromen’s Economic Evolution). But heterodox economists started criticizing the assumptions that economists much earlier than that. Consider the Methodenstreit (method debate) between Carl Menger and the German Historical School in late 19th century (Carl Menger’s defense of economics is presented in his Investigations—originally published in 1883). Or consider Thorstein Veblen’s criticism of the hedonistic conception of individuals in economics and its psychological foundations in his in Why is Economics not an Evolutionary Science? in 1898 (read at your own risk!).
To cut the long story short, heterodox economists and other social scientists have long argued that economics is disconnected from reality. They thought that it is way too abstract, unrealistic, value laden, atomistic, reductionist etc. Many still argue that that—because of these reasons—economic models cannot explain real world phenomena. That economic models are too abstract and unrealistic—also, mathematical and sometimes mathy—is still the most popular criticism against mainstream economics. And it is in fact true that theoretical models in economics utilize unrealistic assumptions: Perfect rationality, perfect foresight, perfect competition, etc.; you name it! Economics also ignore obviously important explanatory—historical, sociological, institutional, psychological, biological, neural, etc.—factors. In fact, economic models look like fictional worlds, fairy tales, or just so stories that have nothing to do with the real world. But does this mean that economics is useless?
The question is whether we can trust economic models and economists on important policy matters that affects millions of people. Or more generally, can we learn anything from abstract, unrealistic economic models? If so how? Economics Rules is yet another attempt to settle the answers to these questions. In order to do so, it presents an account of economic models that accept the aforementioned properties of economic models and argues that it is because of these properties (simplicity, abstraction, unrealisticness, etc.) that economics is a powerful science.
Models are Experiments
Rodrik’s Economics Rules starts with an account of what models are and what models do. Not surprisingly, Rodrik argues that models are simplifications. Economic models isolate specific mechanisms and how these mechanisms work under certain conditions. These conditions are specified by the assumptions of the model.
Rodrik’s account of models has a close resemblance to Uskali Mäki’s account of models. The method of isolation helps economists theoretically remove the influence of some elements on a set of other elements in a given situation, so that they can focus on their desired set of relations in isolation. This makes models similar to experiments. In laboratory experiments, scientists physically isolate the environment from the influence of other factors in order to study the relationships they wish to understand. So, they engage in material isolation. Models are similar to experiments in that they utilize isolation; but that is theoretical isolation rather than material isolation.
“Models are the laboratories of economic theorists. This is a claim most economic theorists will accept, and many of them have explicitly made it. Just as laboratory scientists design and examine the artificial worlds of experimental situations in their laboratories, economic theorists design and examine the artificial worlds of their theoretical models.” Uskali Mäki (in Models are experiments, experiments are models)
Rodrik agrees with this view of models. He argues:
“As with real experiments, the value of models resides in being able to isolate and identify specific causal mechanisms, one at a time” (p. 24)
All this, however, does not fully explain how we can trust economic models that utilize unrealistic assumptions. How can it be that a model that does not describe reality in a faithful manner can help us explain real world phenomena? And how can we know that causal mechanisms specified by a certain highly abstract model is working in the world? This is not an easy question. In fact philosophers of science and particularly philosophers of economics have been struggling to answer this question for a long time (see the reading list at the end of this review).
Rodrik’s answer partly comes from his depiction of critical assumptions and causal mechanisms specified by the model. Despite the fact that economic models are abstract and unrealistic, Rodrik believes that there should be some grain of truth in a model. Although he does not explicitly say this, successful models depict real causal mechanisms—or real tendencies (more on tendencies later). And by way of studying these real mechanisms (or, tendencies) under different conditions, models teach us about possibilities, and likely outcomes that we may encounter in the real world.
I made a similar argument in The Invisible Hand in Economics (Routledge, 2008). Using examples of Schelling’s models of segregation, models of emergence of a medium of exchange and game-theoretical models of conventions, I argued that highly abstract economic models (in my case, invisible-hand models) provide partial potential theoretical explanations. They are theoretical, because they abstract from the specifics of any particular case (there are exceptions to this of course, like applied models that are fine tuned to the particular case at hand). They are partial, because they are limited by the assumptions (isolations) they make. Each model starts with a specific question and represents only specific aspects of reality. A particular model is very unlikely to provide a full explanation of a specific case at hand. They are potential because they may or may not help us in explaining particular cases. As Rodrik argues, the problem of external validity is not specific to physical experiments, theoretical (or, thought) experiments also suffer from this problem. Thus we cannot know right away whether the results of the model can be generalized and carried to the real world (also see Robert Sugden’s Credible Worlds on this). Once we make sure that the model (or, a combination of some models) applies to a particular situation—that is, it represents the case at hand in a satisfactory manner—we may use the model in explaining that particular case. This commonly requires knowledge about the specific case at hand, and sometimes input from other sciences. But why do we trust in highly abstract models? The reason we believe that some of these models (providing partial potential explanations) have a chance of enlightening us about the real world is that we think that they represent a real causal (or, structural) relation—albeit in isolation.
I think Rodrik would agree with most of this. Nevertheless, here is what Rodrik says:
“The correct answer to almost any question in economics is: it depends. Different models, each equally respectable provide different answers. Models do more than warn us that results could go either way. They are useful because they tell us precisely what the likely outcomes depend on.” (p. 17) “The value of models resides in being able to isolate and identify specific causal mechanism, one at a time. These mechanisms operate in the real world alongside many others that obfuscate their workings is a complication faced by all who attempt scientific explanations. Economic models may even have an advantage here. Contingency—dependence on specific postulated conditions—is built into them” (p. 24).
By utilizing a different set of assumptions each model helps economists to study the possibilities in the real world. Thus, in Rodrik’s account, unrealistic assumptions help economists investigate likely outcomes in different settings. However, Rodrik argues, one should still have a reality check: Some assumptions are critical and model results will be true “only to the extent that their critical assumptions approximate reality” (p. 17). “For a model to be useful in the sense of tracking reality, its critical assumptions also have to track reality sufficiently closely” (p. 26). Note however that this concept of critical assumptions is not entirely clear (more on this later).
So, Rodrik argues that each model focuses on some aspects of the real world rather than others. For this reason, he argues, in economics it is more appropriate to talk about tendencies. This emphasis on tendencies echoes John Stuart Mill and Nancy Cartwright. Although Rodrik does not explicate his conception of tendencies in a way that would satisfy philosophers, his basic point is that what we learn from models is context-specific: Model results help economists explore tendencies in the sense that models help us specify likely outcomes of certain isolated causal factors in different settings. Thus, Rodrik argues, it is a mistake to forget this. One should not carelessly generalize a model’s results, because its result are dependent on its assumptions. Rodrik claims that “economics is a social science, and society does not have fundamental laws” (p. 45), thus economists should not behave as if they have discovered fundamental economic laws.
Models as Fables
Rodrik’s characterization of economic models does not end here. He also uses another analogy: Economic models are like fables. Of course, Rodrik is not the first economist to use this useful analogy. See, for example, how Ariel Rubinstein explains the similarity between fables and models:
“As economic theorists, we organize our thoughts using what we call models. The word “model” sounds more scientific than “fable” or “fairy tale” although I do not see much difference between them. […] A good model in economic theory, like a good fable, identifies a number of themes and elucidates them. We perform thought exercises that are only loosely connected to reality and that have been stripped of most of their real-life characteristics. However, in a good model, as in a good fable, something significant remains.” (Rubinstein, in Dilemmas of an Economic Theorist, p. 881)
In contrast to Rubinstein, Rodrik makes a good use of the fable analogy in defending explanatory power of economic models. According to Rodrik, fables are similar to economic models because, fables are simple, fictional (not real), have clear story lines and morals:
The most important part of the analogy is that there are a multiplicity of fables—sometimes with contradictory morals—each for a different situation. But why is this the most important part of the analogy?
“There are countless fables, and each provides a guide for action under a somewhat different set of circumstances. Taken together, they result in morals that appear contradictory.” (p. 20)
Economic models are like fables in the sense that different models give us different and sometimes contradictory results. The moral of the story—policy conclusions we can derive from the model—is context-dependent. Because different models utilize a different set of assumptions, each model tells us about how the specified mechanism might behave under different conditions. Thus, although economic models are simplifications, using a variety of models economists are able to explore a wide range of possibilities. The same mechanism can produce different results under distinct conditions.
The interaction of the rational and economizing agents give us different results in different models. Rodrik gives several examples. For example, he compares firms in a perfect competition setting with firms in a prisoner’s dilemma setting. The difference is: The first setting (model) describes competition among many firms and the latter is used to describe competition among two large firms. Under perfect competition profit maximizing rational firms will bring about a Pareto efficient result. However, in a prisoner’s dilemma setting, Rodrik argues, the market “is not at all efficient” (p. 15). Each model represents two “different versions of how markets function (or don’t). None of them is right or wrong” (p. 16).
So, we have a diversity of models that sometimes contradict each other. However, according to Rodrik, just like simplicity and unrealisticness of economics models, the diversity of models is not a bug, it is a feature. Having multiple models—each representing a different set of circumstances—is why economics is a powerful social science. One may think of models as providing us with a menu of explanatory factors, or a menu of possible explanations. By exploring the model world by way of changing the assumptions of previous models and by developing new models, economists expand their menu of possible explanations. The cluster of models that are relevant to the case at hand become economists’ toolbox in providing explanations to particular cases. By choosing and fine tuning a (or, a set of) model(s) among the long list of available models, economists try to explain particular cases. The longer the list of models, the wider their menu of possible explanations, and the higher their chances to explain the case at hand. This is why the diversity of models in economics is not a bug, but a feature.
Understanding with theoretical models
I may be biased here (you’ll see why), but I think, Rodrik’s most important contribution in this book is to clearly show—with a lot of examples—how the collection of economic models contribute to our understanding despite the limitations of each individual model.
Let me insert another shameless reference to my own work here. Together with Petri Ylikoski from the University of Helsinki, we wrote a paper entitled Understanding with Theoretical Models. The argument in this paper has some similarities to Rodrik’s argument—although in our case it is filled with philosophical jargon. In this paper we have presented a number of claims concerning the epistemic contribution of theoretical models in economics (and elsewhere). Let me list some of the arguments in this paper together with how I think Rodrik’s argument as an economist parallels (confirms?) our thinking:
One should not evaluate theoretical economics models in isolation from other models. This is a mistake that many philosophers and critics—and sometimes economists—make. To put it like Rodrik, they focus on a model, think that it is the model, and criticize it because it is not sufficiently similar to the real world enough.
A theoretical economic model’s contribution to our understanding can only be fully understood if it is considered in a context of a family of related models and of competing explanations for the same phenomenon. In Rodrik’s words, it is the diversity of economic models that gives power to theoretical reasoning in economics.
Theoretical economic models provide modal understanding: they tell how things could be. They also teach us what cannot happen by showing that certain mechanisms cannot generate the speciﬁed outcomes. In fact, theoretical modelling should be understood as how-possibly reasoning. In Rodrik’s terminology this is to say that economics models helps us answer “what questions?” such as “what is the effect of A on X?” and investigate the answer of this question in isolation under different conditions. By way of doing this they teach us about likely outcomes, possibilities: “Just as social reality admits a wide range of possibilities, economic models alert us to a variety of scenarios.” (p. 209)
A theoretical economic model provides us with an essential understanding of certain causal mechanisms—albeit in isolation. By developing a variety of models economists provide us with a more detailed understanding of mechanisms and the possible ways in which they may interact under different conditions. This makes it easier to adapt the mechanisms specified by economic models to particular cases—in providing explanations to a particular case in hand. In Rodrik’s words: “[Economic models] are contextual and come in almost infinite variety. They provide at best partial explanations, and they claim to be no more than abstractions designed to clarify particular mechanisms of interaction and causal channels.” (p. 114, emphasis added).
Main contribution of economists in developing a variety of theoretical economic models is to reﬁne, systematize, and expand the menu of possible explanations. Or in Rodrik’s words: “The multiplicity of models does not imply that anything goes. It simply means we have a menu to choose from and need an empirical method for making that choice.” (p. 73-4)
Scientiﬁc understanding consists of an ability to make correct what-if inferences. Theoretical economic models contribute to our general ability to construct an explanation, new models expand the scope of our explanatory understanding. They allow us to make what-if inferences about a wider set of phenomena. In Rodrik’s words: “What makes economics a science is models. It becomes a useful science when those models are deployed to enhance our understanding of how the world works and how it can be improved.” (p. 83) “Knowledge accumulates in economics not vertically, with better models replacing worse ones, but horizontally, with newer models explaining aspects of social outcomes that were unaddressed earlier. Fresh models don’t really replace older ones. They bring in a new dimension that may be more relevant in some settings.” (p. 67)
I am happy to see that a prominent economist like Dani Rodrik, at least partially, confirms our intuitions concerning theoretical models in economics. Moreover, he presents a lot of examples from history of economics and current debates on economic matters that will help us fine tune our intuitions.
Although I agree with most of what Rodrik says, I also have some small complaints. One of them concerns Rodrik’s conception of critical assumptions. As mentioned earlier Rodrik thinks that there should be some grain of truth in theoretical models: Model’s critical assumptions should reflect reality. But what are critical assumptions? How can we decide whether an assumption is critical, or not? Although Rodik gives some hints, this is not entirely clear. He argues:
“We can say an assumption is critical if its modification in an arguably more realistic direction would produce a substantive difference in the conclusions produced by the model” (p. 26)
This is not very helpful, because one can think of many examples where the results of a model changes as a response to changes in many of its assumption. Is rationality a critical assumption? Is perfect competition a critical assumption? Is “convex preferences” a critical assumption? Is assuming a Cobb-Douglas production (or utility) function critical? The list can go on. Changing these assumptions—making them more realistic—will give us different results under some settings. So how are we going to decide which assumptions are critical?
Although Rodrik gives some examples, I do not think that he resolves this matter satisfactory. But there may be a reason for this. Rodrik argues that “what makes an assumption critical depends in part on what the model is used for” (p. 29). However, as Rodrik—and, Robert Sugden, Uskali Mäki, and David Colander—argues economists do not always provide a users’ guide to abstract theoretical models. More often than not they are silent about what the model could be used for. Moreover, economists sometimes use the same model for different purposes. For this reason identifying critical assumptions may not be as easy as it sounds. It is probably an art, or a craft—requiring economic intuition, experience, etc.—as Rodrik argues: “Good judgement and experience are indispensable, and training can get you only so far” (p. 83). (Note here that Rodrik provides some guidance in the 3rd Chapter of the book.)
How to evade criticism?
So how does Rodrik help economists evade criticism concerning economics? In order to learn that—and many other things–you need to read the book. But here is a chapter by chapter guide to the book.
Chapter by chapter guide to Economics Rules
Chapter 1: What Models Do. The first chapter of the book discusses what models are and what models do. It is in this chapter that Rodrik introduces the variety of models thesis and argues that both unrealistic assumptions and mathematics are useful in economic modelling. He also dismisses the idea that economic models should be more complex and tries to show why we should appreciate the simplicity of economic models.
Chapter 2: The Science of Economic Modeling. In the second chapter, Rodrik makes the case for economics as a social science—distinct from physics. He argues that economics does not have fundamental laws, and economists should not behave as if they have discovered the fundamental laws of economics and society. This chapter also presents a review of what makes models scientific: Models clarify hypotheses, enable accumulation of knowledge, imply an empirical method, and help economists generate knowledge based on shared professional standards. Moreover, in this chapter, Rodrik explains the importance of “second best” thinking, the difficulty of testing economic models, and why knowledge accumulation in economics depends on the development of new models (including explorations of older models—i.e., by way of changing some of their assumptions). Finally, in this chapter, Rodrik presents his take on the Reinhart and Rogoff debate.
Chapter 3: Navigating among Models. In this chapter, Rodrik guides the reader in navigating among models using his own growth diagnostics Then he goes on to explaining the general principles of model selection: How to verify (i) critical assumptions of models, (ii) mechanisms specified by a model, (iii) direct implications of models, and (iv) incidental implications. This chapter also discusses lab experiments, (randomized) field experiments, natural experiments and the problem of external validity.
Chapter 4: Models and Theories. As its title suggests, this chapter discusses the relationship between theories and models. Rodrik demarcates between three questions: What questions (“what is the effect of A on X?”), why questions (“why did some particular event take place?”) and big, timeless questions (“what determines the distribution of income?”). Rodrik argues that economic models answer what questions. Answering why questions requires using particular models or a set of models fine tuned to the specific case at hand—and maybe input from other sciences. Big questions require universal theories, and according to Rodrik it is impossible to formulate universal theories in social sciences. One important argument in this chapter is that general economic theories are frameworks for organizing our thoughts, “rather than stand-alone explanatory frameworks” (p. 116). In order to show this, Rodrik sweeps through history of economics; exemplifying his argument with discussions of theory of value and distribution, and theory of business cycles and unemployment. Later in the chapter he discusses how theories are used in order to explain specific events; using the example of the rise of inequality in US. These types of explanations in economics, Rodrik argues, are not like universal theories, rather they are specific to particular cases. Finally Rodrik argues that economics is a modest science that mostly tries to answer what questions, investigating one cause at a time.
Chapter 5: When Economists Go Wrong. In this chapter Rodrik explains what happens when economists mistake a model with the model and warns against the apparent agreement among economists concerning certain policy proposals. In is in this chapter that Rodrik discusses the financial crises and its aftermath, and the case of Washington Consensus. This chapter clarifies that mistaking a model (more appropriately, economists’ preferred models at the time) for the model is the most important reason why economists go astray. In the case of the financial crisis, the preferred models were models that support the efficient market hypothesis. In the case of Washington Consensus, the preferred models were the models that assume that the main drivers of growth were saving and access to investable funds. So how did economists get it so wrong in both of these cases? Not because they did not have appropriate models (they did), rather they became overconfident concerning some models, and ignored others. They have confused a model, with the In brief, Rodrik argues that economics is not the problem, economists are. Here are some of the mistakes that economists makes: Mistaking a model with the model, overconfidence in a (set of) model(s), false sense of understanding concerning the way in which markets work, market favoritism, inability to connect models with the real world and—for empirical economists—empirics without models.
Chapter 6: Economics and Its Critics. In this chapter, Rodrik responds to critics. He argues that idealization, abstraction, utilization of unrealistic assumptions, methodological individualism are not problems as long as one appreciates the diversity of economic models and accepts the fact that each economic model is an attempt to understand some real world relationships in isolation. Market favoritism is not a problem of economics, and does not require a remaking of economics; it is rather a problem created by some overconfident economists who do not appreciate the diversity of economic models. It is true that economic models cannot be tested like the models in physics, but this is because economics is a social science. Economics deals with this “problem” by way of “expanding the collection of potential applicable models, with newer ones capturing aspects of social reality that were overlooked or neglected by earlier ones” (p. 183). Similarly, because economics is a social science economic models should not be expected to provide precise predictions; rather economics help us make conditional predictions. Contrary to what many critics say, economics is more pluralist than it appears—exemplified by behavioral, experimental and institutional economics. Finally, this last chapter has a discussion concerning whether economic thinking and marketization undermine social values.
Epilogue: The Twenty Commandments. This chapter presents, Ten Commandments for economists and ten for non-economists: these summarize the basic messages of the book for economists and non-economists.
In sum: Economics Rules is an excellent book; a must read for mainstream and heterodox economists, philosophers of economics, policy makers, and of course for economics students.
Let me end the review with Rodrik’s Ten Commandments for economists:
Ten Commandments for Economists
“Economics is a collection of models; cherish their diversity.
It is a model, not the model.
Make your model simple enough to isolate specific causes and how they work, but not so simple that it leaves out key interactions among causes.
Unrealistic assumptions are OK; unrealistic critical assumptions are not OK.
The world is (almost) always second best.
To map a model to the real world you need explicit empirical diagnostics, which is more craft than science.
Do not confuse agreement among economists for certainty about how the world works.
It’s OK to say “I don’t know” when asked about the economy or policy.
Efficiency is not everything.
Substituting your values for the public’s is an abuse of your expertise.”
(Rodrik 2015: 213-4).
Note: All references are to the Kindle (UK) edition:
Rodrik, Dani (2015). Economics Rules: Why Economics Works, When It Fails, and How To Tell The Difference. Oxford University Press. Kindle Edition.
Here is a reading list for those who would like know about what philosophers and philosophers of economists has to say about these matters (in no particular order).