Dennis Rasmussen: The Infidel and the Professor

David Hume is widely regarded as the most important philosopher ever to write in English, but during his lifetime he was attacked as “the Great Infidel” for his skeptical religious views and deemed unfit to teach the young. In contrast, Adam Smith was a revered professor of moral philosophy, and is now often hailed as the founding father of capitalism. Remarkably, the two were best friends for most of their adult lives, sharing what Dennis Rasmussen calls the greatest of all philosophical friendships. The Infidel and the Professor is the first book to tell the fascinating story of their friendship—and how it influenced their world-changing ideas. Read on to learn more about the relationship between these two towering figures in Western philosophical thought.

Who were David Hume and Adam Smith, and why are they important?
Hume and Smith were eighteenth-century Scots who ended up becoming two of the most significant figures of the Enlightenment, and indeed the entire Western tradition. Hume is widely regarded as the greatest philosopher ever to write in the English language. He’s also among the most provocative of philosophers: a powerful critic of both religion and the capacities of human reason, as well as a forceful champion of commerce and the all-around benefits of civilization. Smith is almost certainly history’s most famous theorist of commercial society, or what we’d now call capitalism—in fact, he’s often hailed as the founding father of capitalism. As his modern interpreters never tire of pointing out, though, Smith was far more than an economist who theorized the invisible hand and championed free trade. Instead, he was a professor of moral philosophy who included political economy as just one of his many intellectual interests, and he recognized—to a greater degree than Hume, as a matter of fact—a number of potential dangers and drawbacks associated with commercial society. It’s truly remarkable that two thinkers of this stature were best friends for most of their adult lives; that’s a big part of what inspired me to write the book.

It’s certainly remarkable that they were best friends, but you go so far as to claim that theirs was the greatest of all philosophical friendships. That’s a big claim.
Yes, it is, but I think it’s a warranted one. In fact, it takes some effort to think of who the closest rivals would be. During the course of writing the book this became something of a parlor game that I played with fellow political theorists, philosophers, and intellectual historians: What was the greatest friendship in the history of philosophy? Most people’s first instinct is to say Socrates and Plato, but given the four-decade age disparity between them, their relationship was probably more one of teacher and student, or perhaps mentor and protégé, than one of equals, and in any case the record of their personal interactions is scant. Ditto for Plato and Aristotle. Locke and Newton admired one another, but could hardly be said to be close friends. Heidegger and Arendt had more of a (stormy) romantic relationship than a friendship, as did Sartre and de Beauvoir (with somewhat less drama). As for Montaigne and La Boétie, Lessing and Mendelssohn, Bentham and James Mill, Hegel and Schelling, Marx and Engels, and Whitehead and Russell, in each of these cases at least one member of the pair falls considerably below Hume and Smith in terms of impact and originality. Emerson and Thoreau approach closer to their level, if we choose to count them as philosophers rather than literary figures. The leading contenders among philosophers are probably Erasmus and Thomas More, but in terms of influence and depth of thought most would give the clear nod to Hume and Smith.

You suggest that the context in which Hume and Smith’s friendship took place was almost as remarkable as the friendship itself; can you say a bit more about that?
Hume and Smith were the leading figures of what’s now known as the Scottish Enlightenment, which was really one of history’s intellectual golden ages. Scotland began the eighteenth century as a poor, backward outpost on the fringe of Europe, but Hume’s and Smith’s lifetimes saw the arrival of a vibrant new age of economic prosperity and cultural achievement. Some of the important men of letters of the period, in addition to Hume and Smith, included Hugh Blair, Adam Ferguson, Henry Home (Lord Kames), Francis Hutcheson, John Millar, Thomas Reid, William Robertson, and Dugald Stewart. This Scottish renaissance also comprised natural scientists like the founder of modern geology, James Hutton, the chemist Joseph Black, and James Watt of steam engine fame, as well as artists like the painter Allan Ramsay, the playwright John Home, and the architect Robert Adam. Hume and Smith knew all of these figures personally, and they each play a role in the book. I also describe their encounters with some of the luminaries of the age beyond Scotland, including Jean-Jacques Rousseau, Benjamin Franklin, Samuel Johnson, James Boswell, Edward Gibbon, Edmund Burke, and Voltaire.

Did Hume and Smith influence one another’s ideas and writings, in addition to being close friends on a personal level?
Hume was almost certainly the single greatest influence on Smith’s thought. There are numerous references to him, both explicit and implicit, throughout Smith’s writings. The reverse is less true, as Hume—the older of the two by a dozen years—had composed almost all of his works before Smith even began to publish his, though Hume did write an anonymous review of Smith’s first book, The Theory of Moral Sentiments, soon after its release. That’s not to say, however, that Smith simply adopted Hume’s views wholesale. On the contrary, he modified almost everything he touched. The book explores where and how Smith drew on his friend’s thought and where and how he challenged it on a host of topics, including morality, economics, politics, religion, and the workings of the human mind more broadly.

What’s the significance of the title—why The Infidel and the Professor?
One of the running themes of the book is that Hume and Smith adopted broadly similar views, but very different public postures, toward religion and the religious. Hume was a religious skeptic; he never denied outright the existence of a higher power, but he deemed the principal arguments on behalf of one highly implausible, and he considered the effects of religion to be mostly pernicious. This will be somewhat controversial, but I argue that Smith’s views on this score were substantially closer to Hume’s—that is, substantially more skeptical—than is usually assumed. In making this case I place a special emphasis on a controversial public letter that Smith wrote soon after Hume’s death in which he chronicled—some would say flaunted—the cheerfulness and equanimity of Hume’s final days and described his unbelieving friend as a paragon of wisdom and virtue. Whereas Hume was fairly forthright about his lack of faith, however, Smith generally went to great lengths, in both his writings and his personal life, to avoid revealing his religious beliefs (or lack thereof). These contrary postures led to equally contrary reputations: Hume was christened “the Great Infidel” and was deemed unfit to teach the young—he twice sought professorships, but in both cases the clergy opposed his candidacy decisively—while Smith became a respected professor of moral philosophy.

Does the book break any other new ground?
The literatures on Hume and Smith taken individually are vast, but this is—nearly unbelievably—the first book on the two of them considered together, so it’s easily the fullest account of their personal and intellectual relationship. On a related note, the book also provides the first systematic treatment of Smith’s responses to Hume’s thought over the course of his entire career, from his early essay on the history of astronomy (which was written by 1746) through the final edition of The Theory of Moral Sentiments (which was published in 1790). Still further, the book aims to shift the usual assumptions regarding what’s original and important in Hume’s and Smith’s writings. For much of the twentieth century Smith’s philosophical writings were deemed to be little more than a series of footnotes to Hume’s, and as an economist Hume has long been regarded as a minor predecessor of Smith, insofar as he is taken notice of at all. Ironically, putting the two side by side serves to highlight the importance of Smith’s contributions to moral philosophy and Hume’s to political economy. Smith followed Hume in developing a moral theory based on human sentiments, but his version of moral sentimentalism incorporated several significant improvements on Hume’s. Conversely, Hume argued for free trade and stressed the moral, social, and political benefits of commerce several decades before The Wealth of Nations appeared, and it’s striking how much of that work builds on Hume’s insights.

RasmussenDennis C. Rasmussen is associate professor of political science at Tufts University. His books include The Pragmatic Enlightenment. He lives in Charlestown, Massachusetts.