David Hume and Adam Smith: the Friendship Between Two Enlightenment Thinkers

By Nathan Curland

If you haven’t noticed, we seem to be in the middle of an Adam Smith revival. Competing elements wish to claim him as one of their own. On the right is the conservative Adam Smith Institute (UK), which calls him the father of the capitalist system. On the left are the liberal Scottish defenders of Smith who argue that his theories have been cherry-picked and deliberately misinterpreted by the right to serve their own ends; that, in fact, Smith was not only an economist but a philosopher who understood deeply the pitfalls of unbridled capitalism and warned against its vices.

I learned of these competing claims by listening to Freakonomics Radio’s 3-part series In Search of the Real Adam Smith. This in turn led me to look for writings that might shed light on Smith’s life and philosophical leanings. When I found this book that linked David Hume, probably the most famous atheist philosopher of the 18th century, with the “capitalist” Smith, I was intrigued. What did these two men have in common that would make them such close friends?

Author Dennis C. Rasmussen is an associate professor of political science at Syracuse University and he clearly did a lot of research to put this book together (with a large notes section). His style is easy to read, despite the inclusion of quotes and paragraphs using the English of 18th-century Great Britain. He follows both Hume’s and Smith’s lives from birth to death and, along the way, reminds us of the historical times that they lived through that helped shape their lives and worldviews.

David Hume and Adam Smith are two of the most prominent figures of the Scottish Enlightenment. Hume was older, having been born in 1711 to a Scottish laird, a lower-ranking noble landholder. Smith was born in 1723 to a “modestly affluent” customs officer. Both lost their fathers when they were young and were raised by their mothers. Both families had enough means to send their sons to university: Hume to Edinburgh University at the age of 10 and Smith to Glasgow University at the age of 14. (Rasmussen reminds us that in the early 18th century, Scottish universities were more like boarding schools and didn’t reach their intellectual peaks until the late 1700s.) 

However, neither could count on substantial stipends: Hume as a third child would not inherit his father’s estate and Smith’s mother lacked the means to support him throughout his life. As a result, finances were always on their minds until both, in their own ways and through their own intellects, acquired appointments that eventually made them financially secure.

Both Hume and Smith were brought up in strictly religious Presbyterian households, but both lost their faith in organized religion early in their careers, largely due to their voracious appetites for reading the readily available works of previous “free thinking” philosophers. For example, Hume, according to James Boswell, said he “never had entertained any belief in Religion since he began to read (John) Locke and (Samuel) Clarke.” Smith, by the time he finished his university years, was influenced by the same works but also by the then-available treatises that Hume had published. 

Hume determined early in life that he wished to be known as a philosopher and was not shy about poking at the religious establishment, which was very powerful in Scotland during that period. He also had an affable, gregarious personality and easily made friends, even among much of the clergy. So though he had many detractors, his temperament likely saved him from severe censorship and in fact made him popular among the intelligentsia of the time. It did, however, stand in the way of his obtaining a university position in the religiously controlled Scottish Colleges. 

Adam Smith was more guarded about his nonbelief in his public writings and lectures. As a result, despite some rebukes he might have received from his superiors, he was able to garner a professorship at Glasgow University, where he served for many years. And though he had many friends, unlike Hume, his personality was more introverted and he developed a reputation for being a bit “absent.” He was also a writer known for his preciseness and attention to detail and did not want any of his works that he considered unfinished to be posthumously published. As a consequence, he had many of his papers destroyed after his death by his literary executors. Therefore, we don’t know as much about his deep inner thoughts as we do of Hume’s.

Hume was a prolific writer, mostly essays on various topics that he would pull together into publications over time. Most of his publications were considered controversial at the time because of both his general anti-religion stance and his dislike of the current political parties (Whigs and Tories). He is best known for his two Treatises on Human Nature and his History of England.

Smith, in contrast, developed his thoughts through lectures, both at the university and in public, and carefully pulled them together in only two great works during his lifetime: The Theory of Moral Sentiments (1759) and The Wealth of Nations (1776). Both were very well received at the time and are what made him famous. A third work, Principles That Lead and Direct Philosophical Enquiries, was not published until after his death and was held back by him, likely because of the controversial nature of its topics. (The book revealed his disdain for the clergy and their mixing of religious concepts into university curricula.)

Hume and Smith first met in 1749. At the time, Smith was in his late 20s and giving public lectures, some of which Hume likely attended since they both belonged to a number of societies.  From Hume’s letters, we know they had a lively correspondence thereafter and considered each other close friends the rest of their lives though they resided in different cities (Hume in Edinburgh, Smith in Glasgow).

Philosophically, Hume and Smith had similar worldviews but there were differences, likely due to their different stations. Hume, from a noble household, aspired to philosophy whereas Smith was more concerned about the practical aspects of society. For example, both believed that the only solid foundation for knowledge was through experience and observation, i.e. the scientific method; nor can one wholly rely on reason (because reason relies on a starting premise, which can be in error). However, Smith notes that scientific theories are “inventions of the imagination” and therefore must forever be subject to revision if the observations so require.

When it comes to morality, both agreed that it arises from common human sentiments, i.e. values (sounds like humanism!); specifically, our feeling for approval or disapproval. Under this philosophy, humans are endowed with “sympathy” (better defined today as “empathy”). But Smith had a deeper definition than Hume. Hume saw sympathy as a passive reaction (you smile when someone smiles at you), whereas for Smith it was more of a projection — to feel sympathy you must “walk in the other’s shoes” and understand the “why” for the emotion.

As for religion, both believed that the ultimate standard of right and wrong did not come from divine will. But where Hume believed religion was entirely “pernicious,” Smith saw that it could supply some comfort to the believer and therefore serve as a “buttress” for morality. Furthermore, Smith supported the separation of church and state so that no sect could become powerful enough to control the workings of all society. Hume, however, despite his disregard for religion and desire for religious toleration, favored a state religion in order to “bribe their [the clergy’s] indolence and render it superfluous to be farther active” and make them ultimately subservient to civil authority.

When it came to economics, both Hume and Smith approved of free markets, most especially between states, arguing they would improve efficiencies, while the resulting trade would ease political tensions. They saw the prevailing mercantilism as a philosophy of “beggaring your enemy” and warned about the dangers of imperialism and accumulating large public debt. Smith also warned about the evils of a highly commercial society, such as the tendency of merchants to collude against the public interest. 

Today Smith is widely heralded for the concept of “the invisible hand,” which is used by conservatives to mean the positive feedback loops created by each person working for his or her own gain and unknowingly creating a dynamic thriving society. However, Smith’s meaning was actually more in line with Hume’s notion of the “unintended consequences,” both good and bad, that can result from uncontrolled commerce, thus requiring carefully thought-out constraints.

There is much more to this book for the reader than I can cover in this review. Hume and Smith lived during a highly volatile century and each had their own travels and travails. Multiple wars and insurrections were raging in Europe during this period, which ended with the American and French Revolutions. Rasmussen follows his two protagonists throughout with many anecdotes and history lessons along the way. It is an interesting and enjoyable read.

The Infidel and the Professor: David Hume, Adam Smith, and the Friendship that Shaped Modern Thought, by Dennis C. Rasmussen (Princeton University Press, 2017)