Adam Smith mentions Plato a number of times in the Wealth of Nations, and uses his writings as source on ancient education practices. But to the best of my knowledge only one doctrine by Plato is ever mentioned. Interestingly enough this is not Plato’s account of the division of labor or human inequality—two topics central to the argument of the Wealth of Nations. This can’t be due to unfamiliarity with Plato’s writings because these are used throughout and sometimes in rather specific ways in The Theory of Moral Sentiments.
Rather, at first glance the passage I am about to mention seems to be an aside involving a seemingly minor issue.
The editors of Glasgow Edition quite plausibly suggest that Adam Smith has the following passage of the Republic in mind: “Then good speech and good music, and grace and good rhythm, follow good nature, not that silliness which we call good nature in compliment, but the mind that is really well and nobly constituted in character.” (400) I don’t think that’s right.
the editors of Glasgow edition go on to note, correctly, that the first quoted sentence both cites and echoes Spirit of the Laws 4.8.1:
That judicious writer, Polybius, informs us that music was necessary to soften the manners of the Arcadians, who lived in a cold, gloomy country; that the inhabitants of Cynete, who slighted music, were the cruellest of all the Greeks, and that no other town was so immersed in luxury and debauchery. Plato is not afraid to affirm that there is no possibility of making a change in music without altering the frame of government. Aristotle, who seems to have written his Politics only in order to contradict Plato, agrees with him, notwithstanding, in regard to the power and influence of music over the manners of the people. This I fancy must be explained in the following manner. It is observable that in the cities of Greece, especially those whose .principal object was war, all lucrative arts and professions were considered unworthy of a freeman.
Smith echoes this passage from Montesquieu (which goes on more) already earlier in WN (4.9.47, p. 683), too.*
By contrast, I think it’s pretty clear that Smith and Montesquieu are echoing a really specific point made in the Republic:
For a change to a new type of music is something to beware of as a hazard of all our fortunes. For the modes of music are never disturbed without unsettling of the most fundamental political and social conventions, as Damon affirms and as I am convinced.—Republic 424c in Shorey’s translation [emphases added; Reeve’s “the greatest political laws” may be better for πολιτικῶν νόμων τῶν μεγίστων.]
I have something of an obsession with this passage (recall here; and here) because in it Damon is treated as a recognized authority in the art of government by Socrates. To simplify a bit, Socrates seems to think that musical innovation is very dangerous to political stability. As Montesquieu puts it, there is “no possibility of making a change in music without altering the frame of government.” This sounds less weird to our ears if we recall that music — widely conceived — is central to education and socialization in the culture.
It’s worth noting that compared to Montesquieu, Smith weakens the claim attributed to Plato (and the others): for him music only plays a role in “mending their morals.” One may well think that Smith has ‘refuted’ Plato and Montesquieu (and the others) not so much with an appeal to empirical evidence of the superiority of Romans, but rather by changing the subject (and so is not talking about Republic 424c.)
However, as we have already seen for Montesquieu, music’s role in mending morals is treated as similar to the claim Socrates attributes to Damon. Montesquieu clearly treats the latter as a generalization of the former. This makes sense because the two claims presuppose, in Montesquieu’s hands, the same causal mechanism (viz. musical education or cultivation determines social character of a population). So, by ‘refuting’ the weaker claim, Smith need not concern himself with the stronger claim. (I leave aside how convincing this refutation is.)
I could stop here. But Smith also offers an error theory for the mistake of Plato, Aristotle, and Polybius. The error consists of something like this: long lasting cultural institutions or traditions express, in virtue of longevity, political wisdom either of the founders of society or of wider culture that has preserved tradition (say by finding it useful). And so, the error involved regarding traditions as sacred to political society.
I don’t need to remind the reader that the error itself is a view often associated with Burke, and that some admirers of spontaneous order have also attributed it to Smith. It plays a non-trivial role as common ground in the American political phenomenon known as ‘fusionism’ between conservatism and so-called classical liberalism. My point is that this attribution to Smith deserves considerable qualification given his error theory at WN 5.1.f.40, pp. 775-6.
*“The policy of the antient republicks of Greece, and that of Rome, though it honoured agriculture more than manufactures or foreign trade, yet seems rather to have discouraged the latter employments, than to have given any direct or intentional encouragement to the former. In several of the ancient states of Greece, foreign trade was prohibited altogether; and in several others the employments of artificers and manufacturers were considered as hurtful to the strength and agility of the human body, as rendering it incapable of those habits which their military and gymnastic exercises endeavoured to form in it, and as thereby disqualifying it more or less or undergoing the fatigues and encountering the dangers of war. Such occupations were considered as fit only for slaves, and the free citizens of the state were prohibited from exercising them.”
Bertrand Russell wrote something to the effect that Plato's Republic was a design for a city-state that would be internally stable and good at fighting wars. It's stuck with me, I assume from a long-ago reading of the History of Western Philosophy. I've mentally welded that on to Popper to form a negative view of Plato, without reading him in any depth.