I. Smith’s Approach to Inquiry: Background and Foundations

Smith’s interest in what we now call PPE may come as a surprise to those who know him only as the author of Wealth of Nations. The Wealth of Nations itself famously opens with a defense of the advantages of specialized divided labor, and argues, in the context of its study of the pin factory, that specialized divided labor “occasions, in every art, a proportionable increase of the productive powers of labour” (WN 1.1.4).^{Footnote 3} And for additional confirmation of the remarkable productivity increases that specialized divided labor makes possible, Smith goes on to celebrate its advantages to “those who are called philosophers or men of speculation, whose trade it is, not to do any thing, but to observe every thing.” Indeed philosophers, just like pin makers, are said to be more productive if they focus their attention on ever narrower questions and problems:

In his unpublished drafts of this passage Smith names the sub-specializations that he has in mind, noting that “we have mechanical, chemical, astronomical, physical, metaphysical, moral, political, commercial, and critical philosophers” (ED 2.20). And this, he clearly thinks, is all to the good: the fact that philosophy has been “subdivided into various provinces” explains its increased productivity (LJA vi.43).

Smith thus clearly recognized the benefits of specialization in philosophical or scientific inquiry, and his celebration of its division into ever-smaller “provinces” may seem on its face to read like a challenge to the sort of inquiry PPE involves. Yet these claims need to be read in the context of Smith’s own career as a teacher and researcher. Smith held only one academic appointment in his career, teaching for thirteen years at the University of Glasgow, and his work at Glasgow was in fact consummately interdisciplinary.^{Footnote 4} Smith was originally hired in 1751 as Professor of Logic, and his first biographer reports that in his logic class, “after exhibiting a general view of the powers of the mind, and explaining so much of the ancient logic as was requisite to gratify curiosity,” Smith then “dedicated all the rest of his time to the delivery of a system of rhetoric and belles letters” (Stewart 1.16). This course has come down to us in the form of a set of student lecture notes that have been preserved and published under the title of Lectures on Rhetoric and Belles Lettres. Even a casual reading of this text is bound to leave modern readers impressed by the amount of work that went into the preparation of this course. Yet for all this work, Smith was hardly able to skate by on his initial preparation. In his second year at Glasgow, Smith was appointed to the chair of moral philosophy — a chair that required teaching not simply a new course, but one that we would today consider interdisciplinary. His biographer reproduces a report about this from one of Smith’s former students:

Only two years into his teaching career, Smith was responsible for offering instruction in subjects that we today can recognize as integral parts of disciplines ranging across logic, rhetoric, theology, moral philosophy, law, political science, and economics. Thus for all his celebration of disciplinary specialization in the Wealth of Nations, Professor Smith could lay legitimate claim to familiarity with and indeed a high degree of competence in philosophy, politics, and economics.^{Footnote 5}

Yet what matters for us here is not simply the fact that Smith was interested in these fields, but how he extended and exported insights from one field to others. For example, students of Smith’s moral philosophy know that spectatorship is key to his ethics; the foundational role of the “impartial spectator” has long been a focus of studies of Smith’s moral thought.^{Footnote 6} But spectatorship is also key to his methods of inquiry. We have already had a hint of this in his description of philosophers; recall those “philosophers or men of speculation, whose trade it is, not to do anything, but to observe everything” (WN 1.1.9). Smith’s claim that the activity of philosophy lies in “observing,” along with his explicit association of philosophy with “speculation,” suggests the centrality of seeing to philosophic or scientific inquiry. By making this association, Smith locates himself in an ancient tradition that associates philosophy with seeing; both the ancient Greek word for theory, theoria, and the Sanskrit word for philosophy, darsana, famously find their roots in their respective languages’ words for the verb describing the activity of sight.^{Footnote 7} But what is important for us here is that the sort of philosophical sight that Smith practices focuses on seeing systems. In this sense, the key feature of Smithean philosophical sight — what renders it not just mere sight but insight — is the capacity to see how pluralities of discrete entities are coordinated in a way that forms a coherent whole. This is the sort of seeing that often governs Smith’s inquiries into complex systems. From his studies of the history of science and the history of language to his studies of moral judgments and the price system, Smith aims to show how what might appear to be random associations of discrete entities on closer examination reveal themselves to be integrated wholes composed of interconnected elements. On these grounds, Smith’s inquiry into the fields associated with PPE might be said to be synthetic in two ways. It is synthetic first insofar as it shows how a certain type of philosophical sight can synthesize seemingly discrete and independent pluralities into a unified whole. It is synthetic in a second sense insofar as it bridges multiple fields of inquiry, using the process of generating conceptualizable wholes in one discipline as a template or pattern for similar efforts in other disciplines.

Provisionally then, Smith’s aim as a philosophical or scientific inquirer might be described as an effort to establish the connections that bind together seemingly unrelated and chaotic multiplicities and demonstrate how they might be shown to appear to the mind as stable systems governed by uniform processes.^{Footnote 8} Put slightly differently, Smith can be said to be engaged in a sort of methodological e pluribus unum, generating wholes out of pluralities. Yet this itself requires something more than simply capacity for sight. For sight to become insight, Smithean inquiry also requires a second faculty, namely a capacity for association. As several have noted, Smith’s essay on the history of astronomy prominently highlights the association of ideas — an epistemic concept central to Hume among many thinkers with whom Smith was engaged.^{Footnote 9} But for our purposes, the capacity for associating resembling objects makes it possible creatively to join together objects and ideas in ways that illuminate connections well beyond those evident to sight alone. In this sense, sight and imagination each have specialized roles to play in the labor of Smithean inquiry, with sight affording initial access to the discrete data out of which the imagination subsequently forges synthetic connections, allowing this data to be conceptualized as an interconnected system. This, at any rate, seems to be the process consistently at work in and across Smith’s investigations of questions as diverse as the history of science, the evolution of human language, the emergence of moral norms, and the functioning of economic institutions.

II. The History of Astronomy

Smith’s first sustained written engagement with disciplines beyond those to which he would later be recognized as a preeminent contributor comes in the form of his three essays on the history of astronomy, the history of logic and metaphysics, and the history of physics. These essays tend to be studied today for the light they shed on Smith’s epistemology and his conception of scientific inquiry. To this end, they focus particularly on the way in which the “intellectual sentiments” of wonder, surprise, and admiration, when supplemented by the principles of association, serve to engender and advance scientific inquiry.^{Footnote 10} But in addition to developing a theory of the epistemic faculties at work in the mind of an individual inquirer, these essays also offer intellectual histories of their subjects, tracing their progress and evolution — and it is this side of the essays that is important for our study of Smith’s synthetic approach to inquiry. On this front, the essays aim to establish a coherent synthetic narrative out of a number of disparate items; in this sense, his “history of astronomy” is itself a synthetic enterprise in which a historical narrative is built out of a set of disparate and even conflicting discrete theories that have been linked together to form a chain. The astronomy essay in this way forms a key part of Smith’s larger project of developing what his literary executors described as “a connected history of the liberal sciences and the elegant arts.”^{Footnote 11} Moreover, Smith evidently regards the history of astronomy not simply as a connected linear trajectory but a dynamic and evolutionary system that has recently achieved a stable equilibrium.

To see this, we need to turn to the text itself. After describing the essential intellectual sentiments in the first part of the essay, in the second part of the essay Smith turns to the mechanism of association via resemblance. This has often been read as extending Hume’s understanding of the epistemic faculties of the individual human mind.^{Footnote 12} This is clearly right, but in Smith’s hands it takes on unique broader applications. For when Smith describes the operations of association, he sets forth not merely the core principles of human psychology but also the principles on which he himself will draw in constructing his synthetic history of astronomy. Here is how he begins:

Here Smith describes how individual inquirers synthesize discrete objects. But it also suggests how Smith himself will synthesize the discrete objects of his inquiry — that is, the discrete astronomical theories developed by different individuals over time — into a “history of astronomy.”

The key to this process is an inquirer’s capacity to see a chain that connects one discrete phenomenon to others. This process begins with wonder, the intellectual sentiment that we are said to experience when we are confronted by any discrete phenomenon that “stands alone and by itself in the imagination, and refuses to be grouped or confounded with any set of objects whatever” (HA 2.3). Wonder in this sense prompts a sort of psychic distress, and this distress is heightened when we are confronted not simply by one unconnected phenomenon but “a succession of objects which follow one another in an uncommon train or order” (HA 2.5). In such circumstances, no connection or association can be found between the objects that we see. This is important as it helps Smith to define the opposite of this psychically disturbing state. This more harmonious state is brought about when objects come to be seen as “connected together in the fancy, that the idea of one seems, of its own accord, to call up and introduce that of the other.” This however requires a creative application of the association of ideas by the imagination or “fancy.” Only when the imagination thus comes to extend the initial work done by sight can we in fact see a coherent whole:

In this way imagination supplements the senses, forging connections that enable the building of wholes out of the raw data afforded by sensation.^{Footnote 13} This is especially key for our purposes. Many have noted the role that imagination plays in Smith’s theory of scientific inquiry insofar as it especially helps to build bridges between seemingly disconnected phenomena, focusing especially on how the imagination encourages “the supposition of a chain of intermediate, though invisible, events, which succeed each other . . . and which link together those two disjointed appearances” (HA 2.8). But what remains to be seen is the degree to which Smith himself practices what he here describes; in this sense, Smith, in building his history of astronomy, can himself be seen as engaged in the project of establishing imaginative connections between discrete concepts — in this case, astronomical theories — in such a way that bridges them together and thereby enables a coherent synthetic account of progress in the discipline to emerge.^{Footnote 14}

Seeing this requires turning from the epistemic accounts of Parts 1 and 2 of the essay to the historical narrative set forth in Parts 3 and 4. This narrative is itself consistently governed by two synthetic principles as it develops its evolutionary and progressive account of the history of astronomy. First, it consistently attributes the success of individual theories to a capacity to synthesize phenomena in ways more compelling than those offered by rival theories. In this vein, Smith begins by noting how the “Italian school” was “capable of connecting together, in the imagination, the grandest and the most seemingly disjointed appearances in the heavens” (HA 4.4). He then turns to Eudoxus, who refined the Italian school’s theory of concentric spheres by adding more spheres in such a way that “the imagination could easily attend to and pursue, and which connected together that otherwise incoherent diversity of movements observable in the sphere of the planet” (HA 4.7). So too the rival theory founded on the invention of eccentric spheres and epicycles, sought “to connect together those disjoined appearances, and to introduce harmony and order into the mind’s conception of the movements of those bodies” (HA 4.13). Likewise, Copernicus “without the assistance of epicycles, connected together, by fewer movements, the complex appearances of the heavens” (HA 4.30).

All of these accounts conspicuously emphasize how their subjects forged imaginative connections between discrete phenomena. But Smith’s own activity as a historian of science is guided by a similar ambition. Smith’s narrative is built around a series of instances in which the advances of one theory give rise to “new inequalities” for which a remedy could only be provided by a new theory (HA 4.7); in this way Smith shows how one innovation gives rise to further innovations in an effort to remedy the problems posed by earlier innovations. In this way, the history of astronomy comes to seem less like a series of radical breaks and disconnections and more like a unitary and evolving narrative itself governed by a “chain of intermediate though invisible” connections (HA 2.8). And seen in this way, Smith’s study of the history of astronomy reveals itself to be not merely an account of the principles that govern philosophical inquiry but a philosophical inquiry in its own right. In his conclusion to the second part of the essay, Smith famously describes philosophy as “the science of the connecting principles of nature” (HA 2.12). But in Smith’s hands, the history of philosophy is itself a synthetic and hence philosophical enterprise, one dedicated to discovering the connecting principles of scientific theories and organizing these discrete theories into a coherent and readily grasped whole.

III. Considerations on Language

Smith’s inquiry into the origin and evolution of language provided him with a second opportunity to utilize his skills at synthetic inquiry, and indeed to extend the processes he had first applied in his study of the history of astronomy to a new field of inquiry. This second inquiry was first published in 1761 as “Considerations on the First Formation of Languages.” Smith’s solicitude for the essay is clear, insisting after its first publication that it be appended to the third and all subsequent editions of the Theory of Moral Sentiments.^{Footnote 15} But why was he so attached to the piece? In part this likely owes to its substantive claims, and especially its suggestion that language represents an unplanned medium of exchange — a claim that has been rightly seen as paralleling several substantive claims in his economic thought.^{Footnote 16} But there is also a methodological significance to the language essay, one that indeed connects it to the astronomy essay. For like the astronomy essay, the essay on languages is synthetic in two senses. First, its sketches of the most significant stages in the history of the evolution of language conspicuously emphasize the way in which they emerged as the result of the human understanding’s proclivities to synthetic association. But in addition, Smith’s account of the larger trajectory of the evolution of language can be seen as an effort in its own right to establish the synthetic connections necessary to explain how the discrete and particular elements of language came to be joined into an interconnected system.

The languages essay hits the ground running, declaring in its opening line that “[t]he assignation of particular names, to denote particular objects, that is, the institution of nouns substantive, would probably, be one of the first steps towards the formation of language” (FFL 1). The significance of this opening consists in its emphasis on “particular names” and “particular objects.” In the astronomy essay, as we have seen, science begins with observation of particular phenomena, and goes on to attempt to account for those further particulars that cannot be brought under existing explanatory categories and thereby to bring within its compass the particulars that stand outside of current models. But language, we now learn, seems to evolve in a similar manner. The first nouns, Smith goes on to explain, are assigned not just to particulars, but to “those objects only which were most familiar to them.” Later,

Language evolves along lines similar to those along which scientific inquiry evolves; that is, recognition of resemblance makes it possible to connect unknown objects to known objects. Indeed just as science aims to define laws that hold across a class of objects and which consequently enable us to see such objects as comprising a single system, so “those words, which were originally the proper names of individuals, would each of them insensibly become the common name of a multitude” via “application of a name of an individual to a great multitude of objects, whose resemblance naturally recalls the idea of that individual” (FFL 1-2).^{Footnote 17}

In this way, both science and language progress by employing the principles of apprehension and association to extend generalizations about known particulars to unknown particulars, thereby unifying them under a coherent heading or system. Yet this is only one way in which the synthetic principle works in Smith’s language inquiry. Smith himself is in fact as much a synthesizer and system builder as those rude “savages” that he profiles in his first pages. This is evident as he turns to his larger account of the evolution of language across its various stages. In turning from his explicit focus on individual language users to the relationships of language users across time, Smith employs a set of synthetic principles to account for this evolution. This is especially evident in his discussion of prepositions. Prepositions are the first new part of speech to follow the development of nouns, and they fascinate Smith for their dually synthetic character. On the most basic level, prepositions are formally defined as connecting instruments: “words which express relation . . . in concrete with the co-relative object” (FFL 5). Thus prepositions, like adjectives, are the inventions of one who “must have observed and compared together a great number of objects, must have remarked their resemblances and dissimilitudes” (FFL 7) — that is, ones who are capable not merely of apprehension but also of comparison and imaginative connecting of objects. And Smith makes clear that this requires a cognitive faculty beyond simple sensation: “A relation is, in itself, a more metaphysical object than a quality,” for indeed “qualities are almost always the objects of our external senses; relations never are” (FFL 12).

As Smith begins to chart out the evolution of language in greater detail and over a longer time horizon, his earlier focus on the ways in which language users forged these resemblances begins to give way to an ever more explicit focus on his own emphasis on resemblances. Put slightly differently, just as his narrative of the progress of astronomical science depended on his forging a chain between discrete moments that enables us to see the larger evolution as an unbroken whole, so too his narrative of the evolution of language depends on his forging together various discrete linguistic discoveries into a larger chain that produces a larger whole. This becomes clearer as he comes to treat the evolution of verbs. Smith begins his story on this front noting that even if “the declensions of the ancient languages are so very complex, their conjugations are infinitely more so,” with each complexity owing to “the difficulty of forming, in the beginnings of language, abstract and general terms” (FFL 26). Yet in time, the evolution of verbs comes to represent “undoubtedly a simplification of the language” as that “great variety of declensions” comes to give way to “one universal declension, which is the same in every word” (FFL 33) — a microcosmic illustration of Smith’s basic principle that “language becomes more simple in its rudiments and principles, just in proportion as it grows more complex in its composition” (FFL 41; cf. FFL 30, 36). The key claim here is that the evolution of languages suggests a trajectory toward ever greater unity and simplicity in the same way that astronomy’s progress culminated in the production of a simple and elegant system in which a great number of phenomena could be explained by a single law.

IV. The Moral Sentiments

Smith’s interest in demonstrating how associative connections can help to build unified wholes out of seemingly discrete pieces of information seems evident in his histories of both science and language. But of what significance are these for our appreciation of his contributions to PPE’s central fields of philosophy, politics, and economics? In his ethical and economic writings Smith in fact often employs an approach similar to the one that we have been examining to this point. This section details three manifestations of this approach in the Theory of Moral Sentiments: its account of sympathy, its account of judgment, and its portrait of the one Smith calls “the wise and virtuous man.”

Smith’s theory of sympathy has long been recognized as central to his ethics. Sympathy in fact plays a number of discrete roles in his ethical system, but the most important for our present purposes is its role in the rise of the emergence of moral norms. Smith’s account of how sympathy exchanges function to create universally accepted moral norms is in fact structurally similar to his accounts of the evolutions of both science and language.^{Footnote 18} As we saw above, Smith’s accounts of the evolutions of both science and language are governed by efforts to show how multiple discrete items can be understood as “hanging together” into coherent systems connected by coordinating processes and system-wide laws. This same effort governs Smith’s account of sympathy exchange, which Smith himself largely conceives as an effort to explain how sympathy’s many diverse moral judgments can coalesce on terms of “harmony and correspondence” (TMS 1.1.4.5). As is well known, the challenge here lies in the fact that we always feel much more intensely what affects our own selves than we feel what principally affects other people. Thus for harmony to emerge, on Smith’s account, spectators need to raise the pitch of their concern for others via an effort of sympathy and those being observed to lower the pitch of their concern for themselves through self-command — only in this way can that “correspondence of sentiments between the spectator and the person principally concerned” be brought about (TMS 1.1.4.6). But what is important in this largely familiar process is that the harmony or correspondence that Smith here describes is not akin to simple equality or homogenous uniformity. He knows well that the sentiments of many individuals can “never be unisons”; it is enough if they are merely, as he says, “concords.”^{Footnote 19} Now, these claims do crucial work in Smith’s ethics; as several have seen, Smith here lays the foundations both for his normative insistence on the need to generate a capacity to take on the perspectives of others in society, as well as his understanding of how moral norms can be said to emerge spontaneously and from the bottom up rather than being imposed from on high by elites. But for our purposes, the crucial point is that Smith’s conceptualization of this central feature of his ethics is governed by the same concern that we have seen manifested in several other contexts: namely the effort to uncover the coordinating processes that enable multiple discrete pieces of data to be conceptualized as an integrated whole governed by standards toward which the individual data-points tend to gravitate.

This act of sympathy exchange thus stands as a first instance in Smith’s ethics of the methodological e pluribus unum described above. But this is hardly the only instance. Smith’s account of self-judgment in Part III can be understood on similar lines. Self-judgment, like sympathy, is a central component of Smith’s ethics; as specialists know well, beginning with the fourth edition of the text, published in 1774, a subtitle was added to the work so that its title page announced it as The Theory of Moral Sentiments, or An Essay towards an Analysis of the Principles by which Men naturally judge concerning the Conduct and Character, first of their Neighbours, and afterwards of themselves.^{Footnote 20} As this title suggests, and the book’s argument makes clear, our judgments of ourselves are not the result of any simple comparison of our merits or demerits with an innate or received standard. Thus in a crucial and well-known passage, Smith explains:

This passage has attracted significant attention for the degree to which it seems to suggest Smith’s acceptance of the “social construction of the self.”^{Footnote 21} But it is also significant for its methodological claims. The formal claim here is that it is only by living in society and by studying how all those around us react to us that we come to be provided with the data we need in order to be able to judge ourselves. But at this point we can recognize the degree to which this account is in harmony with Smith’s methodological e pluribus unum. The capacity for self-judgment depends precisely on an agent’s capacity to synthesize into a moral standard the tremendous mass of data afforded by living with others and apprehending their constant judgments of our behavior. Indeed, our principal task as judges of our own selves is to take this multiplicity of data and to distill from it the standard that can serve as a legitimate rule for the ordering of our moral lives.

A third place in the Theory of Moral Sentiments where this methodological perspective is evident is its portrait of “the wise and virtuous man.” Smith presents the wise and virtuous man as a paragon of excellence worthy of our emulation, and in this sense his account of the wise and virtuous man is of key substantive import for his larger theory of virtue.^{Footnote 22} But limiting ourselves again to the methodological significance of this account, what is especially interesting here is the way in which the wise and virtuous man comes to apprehend his conception of moral perfection. On this front, Smith explains,

The excellence of the wise and virtuous man consists not simply in the nobility of his character but also in his capacity for the precise sort of synthetic philosophic insight that has been our focus. Beginning with careful observation afforded by sensibility, the wise and virtuous man takes care to synthesize these discrete observations into a single and “more correct image.” In this sense, the wise and virtuous man is at once a paragon of intellectual as well as ethical virtue, as well as a master practitioner of the synthetic approach that Smith himself practices in his inquiry.

V. Political Economy

How then does Smith’s repeatedly demonstrated interest in synthetic and coordinated processes inform the disciplinary inquiry for which he remains best known, namely his economic inquiry? What follows suggests that Smith’s economic inquiry deserves to be seen as shaped by his commitment to synthetic, exportable pattern uncovering. Indeed his account of the foundational concepts on which his defense of commercial society is built — the division of labor and the price system in particular — are themselves applications of Smith’s synthetic method of inquiry to economic subjects. For just as his inquiries in science and language and ethics were dedicated to uncovering the mechanisms that both coordinate and render coherent seemingly chaotic multiplicities, so too Smith’s economic inquiry aims to show how specific coordinating mechanisms serve to render coherent several phenomena in economics. In this sense, Smith’s economic inquiry cannot be understood simply as an effort on his part to make progress on a set of specific questions that he inherited from previous thinkers. Without denying that Smith was a careful student of available treatments of economic phenomena, his conception of the questions central to economic inquiry seems to have been shaped as much by his methods of engaging non-economic phenomena as by his study of existing economic thought. And insofar as Smith’s economic inquiry is an application of his synthetic methods of studying systems to a new range of human phenomena, his inquiry reveals itself to be exportable, applying the lessons learned in inquiry in fields outside economics to create new insights into economic behavior.

It is beyond the scope of this essay to examine all the ways in which Smith’s economic inquiry in the Wealth of Nations employs this synthetic methodological approach. A full study on these lines would need to examine his treatments of the origin and evolution of money, his views on the advantages of interstate trade, and his treatment of the historical trajectory of and future prospects for interstate order. Here I want to focus only on two places in Book One of the Wealth of Nations where this approach is especially evident: the division of labor and the price system.

Smith of course begins the book, as we have already had occasion to note, with an account of the advantages of specialized labor. Indeed it is precisely the division of labor, he makes clear in his first chapter, that occasions the “universal opulence” extending to “the lowest ranks of the people,” and thus establishes the superiority of commercial society to its rivals (WN 1.1.10). But Smith’s interest in the division of labor owes not only to the remarkable alleviation of poverty that it makes possible, but also to the way in which it achieves these remarkable ends. On this front, Smith presents the division of labor as a coordination principle that makes possible the synthesis of the efforts of a great number of dispersed, discrete agents in a way that replicates his accounts of the coordination mechanisms present in his studies of science and language and ethics.

Smith begins his account of the division of labor with the famous example of the pin factory. His utilization of this example is itself an attempt to make evident to spectators the connections between complex systems that too often aren’t apparent given the limitations of sight itself. A pin factory, that is, is a phenomenon that can be seen at a glance:

Smith here uses the pin factory to help us “see” the unified system that otherwise might well go unnoticed given the great dispersal of the agents participating in the coordinated process. In this sense, the pin factory enables us to catch a glimpse of the analogous but much more complex and much less readily apparent coordination of international labor necessary to produce even such simple commodities as that woolen coat of the worker, which, “as coarse and rough, as it may appear” is in fact “the produce of the joint labor of a great number of workmen” (WN 1.1.11).^{Footnote 23} And it is this capacity to enable the unconscious coordination and collaboration of dispersed agents in the production of necessities of life that renders the commercial system of such wonder to Smith, for indeed, “without the assistance and cooperation of many thousands, the very meanest person in a civilized country could not be provided” with life’s necessities (WN 1.1.11).

A second foundational aspect of Smith’s political economy in Book One of the Wealth of Nations that exhibits this same pattern of coordinating dispersed actors is the price system. Smith, as is well known, regards prices as signals in a complex system that gravitates toward a natural price, itself of course famously determined by the quantity of labor that has been put into the production of the commodity; and thus Smith’s notorious claim, so important to Marx, that labor is “the only universal, as well as the only accurate measure of value, or the only standard by which we can compare the values of different commodities at all times and at all places” (WN 1.5.17; cf. WN 1.5.1).^{Footnote 24} What is important here for our purposes is less the accuracy or inaccuracy of the labor theory of value than Smith’s concern to define a principle that unifies all of these phenomena into a common “standard” which makes possible the coordination of dispersed and discrete data:

Smith would repeat the claim soon afterward, insisting that “the market price of every particular commodity is in this manner continually gravitating, if one may say so, towards the natural price.” This observation itself forms the foundation of one of his most crucial normative claims — namely that it is largely “particular regulations of police” that “keep up the market price for a long time together, a good deal above the natural price” (WN 1.7.20). But again, what matters here is how Smith’s theory of the natural price reflects his consistent concern to show how multiplicities of data can be synthesized into a single and coherent system.

VI. Conclusion

Adam Smith has, and will likely continue to be, seen as a quintessential man of the Enlightenment. He certainly was a polymath, but he was hardly a dilettante. His inquiry into multiple diverse substantive fields was itself unified by a constant commitment to uncovering connecting and unifying principles within each of these fields. Moreover, he employed the techniques of pattern detection that he practiced in each of these inquiries to the task of generating new insights into new fields of inquiry, including economics. In so doing, Smith not only distinguished himself as an early practitioner of what we today identify with PPE, but he also provides a useful point of reference for those doing PPE today. The political and economic and philosophical questions faced by today’s practitioners of PPE of course go beyond the substantive questions Smith faced in the eighteenth century, and thus he offers us no pat answers to today’s substantive and methodological questions. But what his example does offer is a means of describing the transition from more traditional forms of disciplinary inquiry to PPE. Smith’s disciplinary inquiry, as we have seen, articulates synthetic associations that serve to clarify the relationship between various discrete pieces of data. But Smith also goes another step, exporting these associations to other fields in a way that helps to illuminate cognate questions in these fields. In this second step lies Smith’s transition from disciplinary inquirer to practitioner of an incipient form of PPE, and attending to his example can provide today’s practitioners of a more advanced form of PPE one way of demarcating their debts to and differences from specialized inquiries in PPE’s cognate fields.