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Baron de Montesquieu and Adam Smith: Equivalents or Complements?

physiocrats enlightenment french enlightenment montesquieu spirit of the laws henry clark

March 15, 2023

“Montesquieu was the real French equivalent of Adam Smith.” So said John Maynard Keynes in his forward to the 1942 French edition of his General Theory of Employment, Interest, and Money. I was asked recently whether I agreed with Keynes’ statement. It’s a layered question, because Keynes seems to have meant at least two things by his remark. Narrowly, he embraced Montesquieu’s view that interest rates are a function of the supply and demand of money, rather than of savings and investment.1 But more generally, Keynes preferred Montesquieu over the Physiocrats for what he called “his perspicacity, the clarity of his ideas, his common sense (qualities which every economist should possess).”2
The idea that Montesquieu was an economist, worthy of comparison with the Physiocrats and with Adam Smith, may itself strike us as a bit odd at first sight. Generally speaking, Montesquieu is thought of today primarily as a political and constitutional thinker and perhaps secondarily as a kind of sociologist of law. He was an inspiration behind the American founders, the interpreter of English liberty and especially of the ideas of the separation of powers and checks and balances. He was the theorist of limited government, writing in an age that had suffered grievously from the activist governments of the dynastic monarchies.
A closer look reveals, however, that there was a great deal of economic material in Montesquieu’s work. A glance at the Table of Contents shows that at least the cluster of books 20-23 are all concerned with “commerce,” a word that had a somewhat broader reach than it does for us. In addition, book 7 on luxury, book 13 on taxes, and book 18 on topography were also of great interest to the “true” political economists of the age, not to mention the four books he dedicated to climate. His paradox was that, though not really a political economist himself, he was the one author that every political economist of the age felt obliged to engage. Conversely, Adam Smith’s Wealth of Nations was closer in genre to Montesquieu’s work than we might at first imagine. Though its presentation clearly marks it as a treatise on “political economy,”3 the first paragraphs frame it as a work inspired by the most canonical question of contemporary social thought, namely the transition between the pre-civil and the civil state.4
As social scientists, their methodology was much the same: it was to use history, with its comparative study of law and customs, in order to make sense of the human past, the better to guide achieve an improved present. This is in strong contrast, for example, with the Physiocrats, whose approach to economics was less historical, less comparative, more rational-deductive than either Smith or Montesquieu. Like David Hume, who was friends with each of them, they treated the past as the best available laboratory for understanding human nature.
They also shared a certain ambivalence about the public use of their doctrines for political purposes. Montesquieu in particular was reluctant to be associated with an overall set of talking points or take-aways from his work. “I do not write to censure that which is established in any country whatsoever,” he wrote.5 And yet, it is clear at numerous points that he did want to see changes in how some things were done. In the very paragraph after the one quoted, he added that “It is not a matter of indifference that the people be enlightened.”
Smith’s position was also ambivalent, though in a different way. On the one hand, he called his book a “very violent attack . . . upon the whole commercial system of Great Britain.”6 He openly named some of the things he wanted to see changed, often in mordantly polemical language: the apprenticeship system, the guild system, the law of settlement in the Poor Law, sumptuary law, and many others.
On the other hand, he followed his friend David Hume in making a very clear distinction between the philosopher and the mere partisans. The latter, he believed, were destined to adopt a distorted view of the world, the better to display their party loyalty, and ultimately they contributed to the factionalism inimical to popular government. Thus, he contrasted the “legislator,” whose task is to rise above party passions and embrace certain general principles of administration—such as those of political economy itself—and what he calls “that insidious and crafty animal, vulgarly called a statesman or politician,” who always takes his lead from the passions of the moment.7 In a late addition to the Theory of Moral Sentiments, moreover, perhaps in response to the looming upheavals in 1789-90, he invoked the “divine maxim of Plato” against the use of any violence in the advocacy of reforms, however urgent they may seem.8
The audience for both authors prominently included the decision-making elites of their respective societies. In 1784, a major reference work for administrators and diplomats cited Grotius, Pufendorf and Montesquieu as the essential authors amidst a sparse selection. A mere two years later, Smith was virtually the only authority cited. So Montesquieu was seen as a fit source for political economy for decades—until Smith became generally available in a French edition in the mid-1780s.9 A 1788 letter to the Journal de Paris that saw both works as useful for administrators remarked that Great Britain, in producing Adam Smith’s work, had now repaid France for having produced that of Montesquieu. A couple of years later, a reviewer for Le Spectateur national made the somewhat more specific point that the Wealth of Nations represents a new era in “the history of political science, like The Spirit of the Laws.” Some readers regarded Smith’s book as a kind of English response to Montesquieu’s Spirit of the Laws, both of them being general attempts to show how to design a civilized society. One reviewer wrote that Smith “starts with a luminous fact [the division of labor] to then illuminate an immense horizon, that is, to unfold the principles and, so to speak, the contexture of the organization of civilized societies.” Another began by asserting, “everyone knows in a general way that this work by Smith is the most learned and profound analysis ever made of the path of development of human societies, and of the causes that lead them more or less rapidly to prosperity.”10 Even before all this, Smith’s Scottish friend Hugh Blair wrote to him shortly after its appearance: “I am Convinced that since Montesquieu's Esprit des Loix, Europe has not received any Publication which tends so much to Enlarge and Rectify the ideas of mankind.”11
Montesquieu and Smith were each regarded both as apostles and as scientists of liberty. Montesquieu was an inspiration throughout 1789 as upheaval unfolded in France, before being eclipsed by Rousseau in the minds of a more radical breed of activist.12 During the Revolution, too, Smith’s book was recommended to patriots and administrators alike as indispensable: one 1790 compendium promised to put “the science of government and administration within the reach of everyone.” At a later point, revolutionary officials were sent to the provinces supplied with copies of Smith’s Wealth of Nations. Looking back years later, one observer noted that when a French translation of Smith’s work appeared, “all minds were in a state of ferment about political economy and about liberty . . . We read it with eagerness, we learned it by heart, we cited it as an authority.”
As scientists of liberty, both authors subjected commerce to abstract analysis; it was the only way the subject could be rescued from the vested interests. “Liberty of commerce,” wrote Montesquieu, “is not a faculty granted to traders to do what they want; this would instead be the servitude of commerce.” Rule of law and neutrality between merchants and tax collectors is the best way to guarantee this authentic freedom.13 Smith, too, distinguished the interests of merchants from the interests of trade. The whole mercantile system, he argued repeatedly, had been devised for the former as a “conspiracy” against the latter; freedom alone could rescue it from their clutches.14
This freedom thus had a moral valence, as the case of slavery also attests. Each author addressed that question in both a moralistic register and a scientific one. The Frenchman’s treatment of slavery in book 15 contained a withering moral critique of attempts to justify it.15 But it also included an observation in the register of political economy, as Keynes might have noticed: The mines in the Turkish province of Timisoara, he argued, were richer but less productive than those in nearby Hungary: whereas the latter were beginning to use modern machines in combination with free labor, the “imagination of the Turks never went beyond the brawn of their slaves.”16 The idea that free labor was more economically productive than slave labor would have a long future in the debate over abolition.
Smith also spoke in both registers about the subject. As Jerry Muller has recently noted on this site,17 Smith was a moral critic of Atlantic slavery, pitting Africa’s “nations of heroes” against the “refuse of the jails of Europe,”18 a passage that triggered a tract-length rebuttal by one reader.19 But the abolitionist sentiment gathering force throughout the period, culminating in the clubs and societies of the 1780s, had been largely the work of Quakers, Dissenters, and Evangelical Protestants. Smith’s contribution was to adapt and expand upon Montesquieu’s insight by showing at length how economically productive free labor could be. In his unpublished Lectures on Jurisprudence, a work that may have furnished much of the material for what he called his uncompleted “history and theory of government,” he told his students that a humane man would prefer to sacrifice wealth and liberty alike if it were necessary to prevent the expansion of slavery.20 But to contemporary abolitionists such as Thomas Clarkson, his demonstration of the economic inefficiency of slavery was perhaps as useful as his moral condemnation.21
  1. Montesquieu, The Spirit of the Laws, ed. Anne Cohler, Basia Miller and Harold Stone (Cambridge: Cambridge University Press, 1989), 22.19, 420.↩
  2. J. M. Keynes, “Preface,” in Théorie Générale de l’Emploi, de l’Intérêt et de la Monnaie, tr. Jean de Largentaye (Paris: Payot, 1942), 12.↩
  3. Adam Smith, Wealth of Nations, Intro. 8, 11; I.x.n.1, 255; II.v.31, 372; IV.i.35, 450; IV.ix.38, 678-79, and especially IV.ix.51, 687.↩
  4. Smith, Wealth of Nations, Intro. 4, 8, pp. 10-11↩
  5. Montesquieu, “Preface,” Spirit of the Laws, xliv.↩
  6. Correspondence of Adam Smith, ed. Ernest Campbell Mossner and Ian Simpson Ross (Oxford: Oxford University Press, 1977 [Indianapolis: LibertyClassics, 1987]), letter to Andreas Holt, #208, page 251.↩
  7. Smith, Wealth of Nations, IV.Introduction, 428; IV.ii.39, 468.↩
  8. Adam Smith, Theory of Moral Sentiments, ed. D. D. Raphael and A. L. Macfie (Oxford: Clarendon Press, 1976; repr. Indianapolis: Liberty Fund, 1982), VI.ii.2.16 and VI.ii.2.18, 233-34.↩
  9. See my review of Kenneth E. Carpenter, The Dissemination of the Wealth of Nations in French and in France: 1776-1843 (New York: The Bibliographical Society of America, 2002), in Adam Smith Review (2004) for this and the following paragraphs.↩
  10. Mercure de France, 12 (March 22, 1788):171-75, and Gazette nationale, 220 (April 30, 1802):891-92, both cited in Carpenter, Dissemination, 69, 188; see also 74, 92.↩
  11. Correspondence of Adam Smith, letter from Hugh Blair, letter #188, page 151.↩
  12. Renato Galliani, “La Fortune de Montesquieu en 1789: un sondage,” in Renato Galliani and F. Loirette, eds., Études sur Montesquieu (Paris, 1981), 31–47.↩
  13. Montesquieu, Spirit of the Laws, 20.12-13, quote at 345.↩
  14. Smith, Wealth of Nations, book four; see also quote at I.x.c.27, 145.↩
  15. Montesquieu, Spirit of the Laws, book 15, esp, 15.2 and 15.5 on the Atlantic slave trade.↩
  16. Montesquieu, Spirit of the Laws, 15.8, 253.↩
  17. Jerry Z. Muller, review of Jacob Soll, Free Market: The History of an Idea, on “Adam Smith Works,” Jan. 11, 2023.↩
  18. Smith, Theory of Moral Sentiments, V.2.9, 206-7.↩
  19. See Arthur Lee, An Essay in Vindication of the Continental Colonies of America, from a Censure of Adam Smith, in His Theory of Moral Sentiments (London, 1764).↩
  20. Smith, Lectures on Jurisprudence, ed. R. L. Meek, D. D. Raphael, and P.G. Stein (Oxford: Oxford University Press, 1978; repr. Indianapolis: Liberty Fund, 1982), 185.↩
  21. Daniel B. Klein, “Adam Smith’s Rebuke of the Slave Trade,” The Independent Review, 25, no. 1 (Summer, 2020):91-98, esp. 97-98, citing Clarkson’s 1808 history of abolitionism.↩