The positive economist in retrospect
 

Jennifer Burns: Milton Friedman: the last conservative. New York: Farrar, Straus & Giroux, 2023, 578 pp.

 

Milton Friedman is perhaps best known in philosophy of science for his 1953 essay “The Methodology of Positive Economics,” in which he famously defended the view that economic theories should be assessed for the accuracy of their predictions and not the realism of their assumptions. Over the ensuing six decades, philosophers of economics and the social sciences furiously debated Friedman’s claim time and again, either on its own grounds or by connecting it to broader philosophical positions (canonically, Popper’s). Thanks to the historian J. Daniel Hammond, who extensively interviewed Friedman and explored his archive, philosophers of economics already had a decent grasp on how Friedman built his methodology (e.g., Hammond 2009). However, there are still some good reasons for a philosopher of science to plunge into Jennifer Burns’ new archivally based biography of Friedman.

For a start, it allows us to reconsider Friedman’s methodological piece from a different angle: its politics. In presenting himself as willing to recommend only those economic policies whose predictions were best supported by the evidence, Friedman cultivated an image as someone who, assuming some shared values, sought to build a political consensus on economic policies, urging the economic profession generally to predict the most likely effects of their theories and advise policymakers only on the grounds of empirically validated predictions. Through Burns’ biography, however, we learn how far from consensus-seeking Friedman was as an economist up to the publication of his 1953 piece and beyond. To be sure, economics had been a polarized discipline long before Friedman joined its rank, with the late-nineteenth-century division between classical and progressive economists giving way by the era of the Great Depression to a division between neo-classical and institutional economists, with young Friedman (born in 1912) by then a front-row spectator. The first part of Burns’s biography maps all these controversies onto the landscape of US economic policy, locating Friedman’s personal and intellectual development at each stage.

Friedman lost no time in joining the battle. Already as a graduate student, he started challenging the few existing areas of consensus among his senior colleagues. His doctoral advisors and employers at the National Bureau of Economic Research had to deal with Friedman’s research on the monopolistic practices of the American Economic Association – too hot a topic for a supposedly non-partisan economic observatory. After a protracted negotiation, Friedman got away with his claims. “There is no significant study in the field of economics whose results are not likely to be used in public controversy”, argued Friedman (92). But he also engaged in private controversies. For almost a decade, he went back and forth between academic jobs and the US Administration, taking active part in the internal politics of both, usually with polarizing effects. For instance, Friedman’s well-known fight against the Cowles Commission, masterfully dissected by Burns, was by no means a purely intellectual quarrel about their differences on how to test a model. Friedman actively chased Cowles out of Chicago, formally advising against further funding, preventing academic appointments and personally harassing some of its members. “A collective picture of Friedman was emerging,” claims Burns: “a retrograde thinker at best, a political hack at worst” (201). When he obtained the prestigious John Bates Clark medal in 1951, it was not because of his success as an apolitical consensus-builder but in spite of his reputation as a deeply political controversialist.

According to Burns, Friedman nevertheless went on to distance himself from that reputation through his collaborations with four overlooked women: Anna Schwartz, Rose Friedman (his wife), Dorothy Brady and Margaret Reid. Burns shows how many of Friedman’s masterpieces, e.g., on the monetary history of the US (Friedman and Schwartz 1963) or on the consumption function (Friedman 1957), originated in his regular exchanges with all these female economists with whom he engaged in egalitarian exchanges, at least until the point of publication, where often he claimed authorship. Burns explores the complexity of these personal dynamics, in particular in his marriage, leaving readers to reach their own conclusions.

In the second half of the book, Burns explains how the positive economist became the public intellectual between the 1960s and 1980s. First came the political essays published in his collection Capitalism and Freedom (1962), followed by his regular columns in Newsweek, and later on by his television series and book Free to Choose (1980), all of them developed with the crucial assistance of Rose Friedman. In parallel, Friedman became an advisor for politicians in the US and abroad, reaching his simultaneous apogee and nadir under Richard Nixon’s presidency. The latter part of Burns’ biography becomes, in fact, a political history of the US, tracing Friedman’s efforts to articulate a form of libertarian conservatism, with mixed success. For Burns, his anti-poverty policy, enacted via the negative income tax, had a better posterity than his compromises on the fight against segregation.

From a methodological standpoint, it is interesting to see the role Friedman’s predictive abilities played in this second half of his career. Burns illuminates Friedman’s long fight to orient the policy of the Federal Reserve according to the measures of the money supply that he and Schwartz had constructed in A Monetary History of the United States. Money-supply measures such as M2 were held to predict, most significantly, inflation – a major policy target in the turbulent 1970s. Under Nixon’s presidency, Friedman would have direct access to the chairman of the Federal Reserve, his old mentor Arthur Burns, and indirect access to Nixon through his former Chicago colleague George Shultz.

Despite their personal connection, Friedman never succeeded at persuading Arthur Burns – an institutional economist at heart – about his monetary predictions. Just as had happened a decade earlier, in the famed “battle of the radio stations” (so called because the initials of the principal combatants were AM and FM), Friedman’s predictions were not so difficult to challenge: it was enough to dispute which construct rightly measured the importance of money. Even if a monetary aggregate yielded several right predictions – as did happen to Friedman’s in the early 1970s – it could lose its predictive traction without warning. When, in the 1980s, under Paul Volcker, the Fed started to track systematically several monetary aggregates, it was unable to anticipate the effects of its own interventions, to Friedman’s perplexity. In the words of Jennifer Burns, “Slowly, painfully, Friedman would learn that monetarism was built on data from a world that no longer existed: the regulated and regimented postwar era, the land the New Deal built and inflation swept away” (397).

Friedman had rightly captured the importance of money and the role of the Fed in managing it, persuading both his fellow economists and US public opinion. However, this persuasion was not achieved through an array of successful predictions about well-defined variables, as per Friedman’s positivist stance. According to Burns, the key to Friedman’s persuasion is that his ideas “matched experience, offered new ways to tackle old problems, and predicted what would happen next” (468). Using the venerable hedgehog-or-fox dichotomy, I’d say instead that Friedman was an economist hedgehog, a thinker with one big idea from which bold predictions follow, as distinct from the eclectic foxes who put together different information sources to make more accurate forecasts. It was enough that Friedman’s predictions about inflation were broadly correct a few times, at the right moments to capture the world’s attention. Nobody seems to have cared much about the details of his predictive record, e.g., how much better the predictions from his monetary aggregates were compared with those of his competitors.

Friedman certainly offered new ways to tackle old problems; but rather than matching his audiences’ experience, he shaped it with his incessant public engagement. In this, he was perhaps more of an artist than a scientist. His engagement skills – boosted by his wife’s assistance – went well beyond the stereotype of the positive social scientist he might have wanted to be at the start of his career. In my view, philosophers of the social sciences who want to capture what Friedman was need new categories about what social scientists can and should be. Burns’ biography is an excellent case study to test their predictions.

References

Hammond, J. R. 2009. “Early Drafts of Friedman’s Methodology Essay.” In U. Mäki, ed., The Methodology of Positive Economics. Cambridge: Cambridge University Press, pp. 68-89.

Friedman, M. 1953. “The Methodology of Positive Economics.” In Essays in Positive Economics. Chicago: University of Chicago Press, pp. 3–43.

Friedman, M. 1957. A Theory of the Consumption Function. Princeton: Princeton University Press.

Friedman, M. 1962. Capitalism and Freedom. Chicago: University of Chicago Press.

Friedman, M. and Friedman, R. 1980. Free to Choose: A Personal Statement. New York: Harcourt.

Friedman, M. and Schwartz, A. 1963. A Monetary History of the United States, 1867–1960. Princeton: Princeton University Press.

 

{2024}{Metascience} 

 

Completing the landscape on models and scientific representation 

Roman Frigg: Models and theories: a philosophical inquiry. London:Routledge, 2022, 495 pp, 

Open access at: https://www.taylorfrancis.com/books/9781844654918

“What are theories? What are models? And how do models and theories relate to each other? These are the core questions that this book is concerned with” (1). These expansive questions predictably give rise to a monumental 500-page monograph that Roman Frigg presents as, at once, an introduction, a literature review, and a critical assessment (1). On all these tasks, the book works very well. Unlike standard textbooks, Frigg does not indulge in didactic simplification: he smoothly walks the reader from the elementary concepts to the upper echelons of the question under analysis.  Having been an active participant or direct witness of two decades of debates on the title topics, Frigg’s scholarship and insight are often extraordinary. And so is the organization of the material presented. In a time where books are often collected papers in disguise, here discussions are systematically developed through the book’s four parts until each of the running threads is exhausted. Yet, the number of cross-references and signposts makes it almost impossible for the reader to get lost.

Reviewing this book requires hard choices. I will mainly focus on the first two parts in which Frigg presents his original view of the old masters’ views in our discipline, from Carnap to Suppe, hoping it will be less known to the average reader than the content of parts three and four. In them, Frigg discusses the last forty years of work on models and scientific representation, completing the landscape that he had already presented in his previous volumes. 

The first part of the book introduces the Linguistic View of Theories: “a scientific theory is a description of its subject matter in a formal language” (5). Frigg’s first move is to separate the Linguistic from the traditional Received View (RV) to make his initial claim: the latter may have fallen, but the former lives on.  Both are based on three principles, and the first two are reasonably similar between the two views: 1) “The language in which the theory is formulated has a logical structure that allows scientists to derive propositions from other propositions and to formulate proofs of theorems,” and 2) “A theory contains general principles, or axioms, which are the theory’s laws” (18). The difference lies in the third principle: 3) whereas for the linguistic view, in the language of the theory there are pre-theoretical terms and technical terms that arise within the theory, in the Received View, the terms are either logical or extra-logical and the latter are further divided into theoretical and observational.

Frigg rehearses, in Chapter 1, some standard objections against the RV, showing that most of them are based “either on misattributions, misunderstandings, or on hasty conclusions” (25). The real problems for the linguistic view appear in the following three chapters, and they are addressed in an equally constructive way. In Chapter 2, Frigg presents the role of models in the RV as alternative interpretations of a theory’s formalism, i.e., as logical models without any representational role. A consequence of the denial that models play a representation role is that according to RV a theory is connected to the world only by the observation terms and correspondence rules. A persistent strand of argumentation is that the limiting results in first-order logic, notably Gödel’s first incompleteness theorem and the Löwenheim-Skolem theorem, show such an analysis to be untenable. But, Frigg observes, these arguments are not conclusive, and they would only be a problem if the RV was inextricably tied to first-order logic, a claim for which he finds no evidence.

The challenge discussed in Chapter 3 is whether the distinction between theoretical and observation terms is tenable, to what extent observations are theory-laden, and how the relation between observation and data should be understood. Frigg concludes that the distinction between observation terms and theoretical terms should be given up and replaced by a dichotomy between antecedently understood and new terms, where the latter might be analysed in terms of Balzer, Moulines and Sneed’s notion of the T-theoreticity. This leaves the question of how data models fit into a linguistic view of theories. According to Frigg, the linguistic view is not reductive in this regard: scientific data should not be reduced to sentences to understand their epistemic input on a theory, data models can also do the job. 

Chapter 4 is about the semantics of theoretical terms, and how to define them. Although the review of the alternatives under discussion is significantly longer than in any other chapter—starting with verificationism ending with the causal theory of reference—Frigg takes no sides here. “This is still an active field of research” (140) is the chapter’s bottom line. Probably he does not need to take sides: of the three principles defining the RV, he just needs the first two, pertaining to the logical structure of theories and the presence of axioms, to assert the viability of the Linguistic View.  

The next step is to show the compatibility of the Linguistic View with the Model-Theoretical View (MTV), in which a scientific theory is mainly a family of models. Frigg had already warned his readers, in the first part of the book, that his “liberal” version of the RV is “in fact indistinguishable from a liberal” MTV: for both, the analysis of theories should be formal; in the liberal RV a theory would be “a language with a family of models”; in the liberal MTV a theory would be a family of models with a language. Here is another foundational claim of the book: “The consensus then is that any reasonable analysis of a theory must be a dual view” (167). 

The second part shows how far this consensus goes. Chapters 5 to 7 deal with the mainstream version of the MTV, in which models are mathematical structures.  Chapter 5 presents Suppe’s foundational ideas, lists the main developments of this view, and considers how the MTV solves the problems discussed in Part 1. New problems, of course, appear—-e.g., do models constitute or represent a theory? Crucially, Frigg presents here his case for having language as a key ingredient of the MTV. 

In Chapter 6, he hammers this point in a thorough discussion of the representational role of models in the MTV, in which Frigg draws on his previous work on scientific representation to map the territory with several adequacy conditions and reference problems. Two contending approaches are considered: the Data Matching Account and the Morphism Account. In the former, “a model M is a scientific representation of target T iff a measurement performed on T yields data model D and D is isomorphic to M’s empirical substructure” (212).  Siding with Bogen and Woodward, Frigg quickly discards it, arguing that the theories represent phenomena, not data models. In the Morphism account, “M is a scientific representation of T iff M is isomorphic to T” (201). The first problem here is in specifying in what sense the objects in the target system are a structure isomorphic to a set-theoretic M. And then Frigg proceeds to show in detail how morphism accounts are ill-equipped to deal with some desiderata that any view of scientific representation should meet. 

Chapter 7 explores the links between models belonging to the same theory in the light of the Munich structuralist school, Balzer, Moulines, and Sneed. The distinctions introduced in this account to deal with the different models within a theory successfully illuminate problems like theory-ladeness. But the Munich school does not have a solution for the problems so far detected in other structuralist accounts.
Chapter 8 completes this second part examining Giere’s and Suppe’s non-structuralist accounts of the MTV. Although the key ingredients are now models conceived as abstract entities representing the world through similarities, these accounts equally fail to meet Frigg’s desiderata for scientific representation, for the same underlying reason: language also plays an essential, but unexamined role in these alternative versions of the MTV.  

We are now halfway through the book. The lesson that emerges clearly from the discussion is that “purist” versions of either the linguistic or the model theoretical view are untenable. As Frigg puts it in the Envoi: “Any tenable account will have to see theories as consisting of both linguistic and non-linguistic elements” (490). This means that a defensible analysis of theories must be a dual view. Frigg’s discussion at this point remains programmatic. He sketches the main outlines of a dual view, but he leaves the task of working out the details of such a view to future research.  

In the third and the fourth part, we are treated to an in-depth exploration of twenty-five more years of controversies on scientific representation. Unlike the previous two parts, there will be no unifying threads like the RV or the MTV: the focus is now on models in scientific practice, without any overarching program of rational reconstruction. 

Each chapter in Part 3 deals with open questions about how models represent. In Chapter 9, we find several contenders for the very notion of scientific representation: namely, direct representation, inferentialism, and representation-as approaches. The next three chapters present critical discussions of specific kinds of representation via models: analogy in Chapter 10, abstraction and approximation in Chapter 11, and idealisation in Chapter 12. Whereas Chapter 9 closes with an overview of Frigg’s own DEKI account (where the acronym stands for denotation, exemplification, keying up, and imputation), on which he has extensively published elsewhere, the other chapters in this third part are critical assessments of the state of the art in the respective subject areas.

In Part 4, the author really struggles not to be carried away by casuistry and find philosophical threads connecting an immense and disperse literature. The opening thirteenth chapter engages in a mostly case-based debate on the autonomy of models from theories. Frigg provides a reasonably representative sample of how this autonomy has been analysed in the models in scientific practice literature. We also find a very nice overview of the debate between some leading authors in this approach and their counterparts in the MTV on whether the latter’s account of models captures the diversity of scientific practice—Frigg doubts it. The three final chapters are also opinionated. In Chapter 14, discussing the ontology of models, Frigg sets some desiderata and defends his own Waltonian fictional account, in line with DEKI. Chapter 15 deals with some philosophical dilemmas arising from the proliferation of models, exploring, for example, how robustness analysis exploits it for good or how perspectivism makes sense of the variety. These are ongoing debates, and the challenges Frigg proposes for the latter view are, in my view, worth considering. The last chapter, Chapter 16, contains an original classification of model types that I will just quote, for the sake of brevity: “1) Model types pertaining to model-target relations; 2) Model types pertaining to carriers; 3) Model types pertaining to the process of model construction and to models’ relation to theory; 4) Model types pertaining to the uses and functions of models in the scientific process” (467–468).  

What is the moral that the reader should draw from this second half of the book? In the final “Envoi”, Frigg is at once short and ambitious: “The next step in a discussion of representation will be to get to a better understanding of particular representation relations and the styles to which they belong, as well as to integrate an account of how models represent into a broader understanding of the structure of theories” (490). In other words, merge the main threads of this book into a unified view. Frigg has masterfully laid out the foundations of this project for any newcomer in the discipline, like Suppe did with his own volume in the 1970s. We can only hope it will orient future debates with similar success.

{January, 2024} {Metascience}

The rule in the knowledge machine

Michael Strevens, The Knowledge Machine: How Irrationality Created Modern Science, Liveright, New York, 2020, 350 pp. hard-back, 30$

The Knowledge machine is a book about the Iron rule of explanation (IRE). According to Michael Strevens, science has worked because scientific communities have strictly played by this rule ever since Newton. In the author’s own words, this is:

The rule demanding that all scientific arguments be settled by empirical testing, along with the elaborations that give the demand its distinctive content: a definition of empirical testing in terms of shallow causal explanation, a definition of official scientific argument as opposed to informal or private reasoning, and the exclusion of all subjective considerations and nonempirical considerations (philosophical, religious, aesthetic) from official scientific argument. [293]

With the IRE Strevens wants to settle the Great Method debate, initiated by methodists like Popper and Kuhn and then dominated by radical subjectivism (now prevalent among historians and sociologists of science). According to Strevens, the former focused on the wrong rule, be it falsificationism or the organization of scientific paradigms. The latter deny that there is any correct rule,  scientific outcomes are just like any social agreement, a matter of taste, interests, power etc. Strevens accepts the role of all these factors in the dynamics of science, but condensed into plausibility rankings, “a scientist’s level of confidence that a hypothesis or other assumption is true” [293]. But subjectivity is then constrained by the IRE: the game of science is about scientists organizing empirical tournaments in which a winner emerges, independently of the conflicting interests or values of the participants. According to Strevens, the accumulation of evidence, in the long run, brings about consensus on the true theory, the one that explains all relevant observations.

The gist of the iron rule is to minimize scientific debate about things scientists may not easily agree on and motivate scientists to “squeeze every last drop of predictive power” from a scientific paradigm. For Strevens, playing by the IRE and only the IRE is irrational: the IRE “imposes a wholesale prohibition on all forms of nonempirical thinking, no matter their track record, no matter how well they synergize with empirical observations” [237]. A chapter on the fruitfulness of beauty as a guiding principle of science exemplifies this point. But the alternative (using some other guiding principles in addition to the IRE) is worse: scientists may never reach an agreement.

Strevens discusses the Thirty Years’ War to illustrate how making religion a private matter is the best strategy to avoid civil unrest, and modern science would have its foundation in this separation. The recipe is still valid today: Keep empirical tests separate from any other consideration and let these tests proceed until a consensus is reached, keepscience working like a well-oiled automaton (a knowledge machine), do not meddle with the IRE.

Although Strevens is famous for his dense prose and subtle conceptual analyses, The Knowledge Machine was conceived as a popular philosophy book, an a quite successful one at that –already with reviews in major international newspapers and magazines such The New Yorker. A reason for this lies in the long collection of snapshots in the History of science that illustrate the concepts presented above and make for a fun reading. Radical –and a few moderate- subjectivists will probably challenge the details of these abridged case studies, but this is a scholarly debate, for which Strevens will probably be ready –although the footnotes and references are rather sketchy so that it is often difficult to determine the depth of his knowledge of each particular case.

What was less clear to me though was the message this book is sending to the public. As Strevens acknowledges in the first half of the book, his predecessors in the Great Method Debate were all conveying an image of scientists that became hugely influential among the educated Westerners: the Popperian dissenter, the Kuhnian Cold warrior, the Latourian black-boxer. These images made plain sense against the background of the political dilemmas of their time, partly reconstructed by Strevens for his readers. However, about our own dilemmas, Strevens remains mostly silent and his final advice sounds almost like an oracle: “Do not tamper with the workings of the knowledge machine. Set its agenda, and then step back: let it run its course” [285]. Strevens does not explicitly says  who is meddling with the IRE and who would oppose it after grasping Streven’s consequentialist argument. Perhaps a few ongoing agendas in philosophy of science (and on Science and Technology Studies) could be seen as targeting the IRE. Feminist standpoint theories, for instance, defend a reassessment of what counts as evidence to illuminate potential sexist biases. Similarly, advocates for the embedment of philosophers in scientific laboratories claim that conceptual analyses can have a real impact on the advancement of science. Would any of these approaches count as threats to the IRE?

Perhaps  more serious meddlers  are the many forms of populism proliferating around the world. After all, the IRE has a technocratic taste: once their goals are set by democratic parliaments, science, like hospitals, courts, or central banks, work better as independent institutions where experts make relevant decisions according to their own rules. Challenging the autonomy of science in the name of “subjective or nonempirical considerations” would be a typical populist move. For instance, I would count as populist the call to accommodate  patients’ preferences in the design of clinical trial at the expenses of traditional debiasing methods (such as blinding). But I cannot tell whether this is the sort of challenge with which  Strevens is concerned because almost of all of the examples discussed in the book are success stories from the natural sciences before 1950.

It is always nice to be reminded of how well some scientific disciplines have worked in the past and, at least to me, the IRE seems a plausible account for this success. But I am not sure about the effectiveness of such a reminder in persuading contemporary audiences about the benefits of the autonomy of science. My first concern is that such reminders have been tried before with not much success. Reading The Knowledge Machine, I could not but think of Max Weber’s arguments about the scientific vocation. Like Strevens, Weber was inspired by how the Protestant reformation and brought about a world in which the private faith of individual agents had unintended beneficial consequences for everyone (i.e., economic growth), provided that the Church and the State were kept apart. Like Strevens, Weber praised scientific specialization and called for leaving aside all value judgments so as to prioritize consequentialist considerations. And yet the Great Method debate started because, after World War II, only Merton was persuaded that a general code of conduct was enough to account for the success of science. WillStrevens’ arguments be more persuasive today?

I agree that having clearly articulated (iron) rules will  increase the public trust in any institution. Nonetheless, my second concern is that the problem we are now facing is the increasing mistrust regarding the enforcement of any such rule. Think again of randomized clinical trials in medicine: despite the conflicting interests at stake, the systematic implementation of the IRE allows the truth about whether medical treatments work to emerge with the accumulation of evidence (thanks, e.g., to the Cochrane collaboration). And yet more and more patients are persuaded that the whole testing system is bankrupt because some particular trials are rigged by their corporate sponsors. A Weberian reminder that scientists have successfully played by the IRE in the past to everyone’s satisfaction and that we should keep their effort going will do little, in my view, to appease an audience sceptical about whether the IRE is being enforced today

But maybe I am overinterpreting Strevens’ argument. After all, defending science from the meddlers is just the topic of 7 pages out of 300. Perhaps this is just a public reminder that science works for a very simple reason that the examples in the book easily convey. It is an entertaining read and it will help to comfort any Weberian soul struggling to keep alive her faith in science in our increasingly challenging world. At least, it has helped me. 

{August, 2021}

{Metascience}

 

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