Dennis Rasmussen: National Friendship Day

Today, August 6, is National Friendship Day. Rather than celebrate this Hallmark holiday by sending a slew of greeting cards, as its originators hoped, I propose to use it to raise and answer a fascinating but seldom-asked question: What was the greatest friendship in the history of philosophy?

I am convinced that the answer is clear, once the leading contenders have been considered: the greatest of all philosophical friendships was that of David Hume and Adam Smith. Hume is, after all, widely regarded as the most important philosopher ever to write in English, and Smith is almost certainly history’s most famous theorist of commercial society, or what we would now call capitalism. They are two of the most significant figures in the entire Western tradition, and they were best friends for most of their adult lives. My new book, The Infidel and the Professor, follows the course of Hume and Smith’s friendship from their first meeting in 1749 until Hume’s death more than a quarter of a century later, examining both their personal interactions and the impact that each had on the other’s outlook.

During the course of writing the book I frequently invited fellow political theorists, philosophers, and intellectual historians to nominate alternative friendships as the greatest in the history of philosophy. Most people’s first instinct was 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 strongest 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.

Given their stature and influence it is remarkable that no book has heretofore been written on Hume and Smith’s personal or intellectual relationship. One likely reason for this is that friendships are more difficult to bring to life than feuds and quarrels: conflict makes for high drama, while camaraderie does not. It is perhaps not surprising, then, that there have been many books written on philosophical clashes—think of David Edmonds and John Eidinow’s Wittgenstein’s Poker and Rousseau’s Dog, Yuval Levin’s The Great Debate, Steven Nadler’s The Best of All Possible Worlds, Matthew Stewart’s The Courtier and the Heretic, and Robert Zaretsky and John Scott’s The Philosophers’ Quarrel, to name only a few recent titles—but far fewer on philosophical friendships. Even biographies of Hume tend to devote less attention to his long friendship with Smith than to his brief quarrel with Rousseau, which, sensational as it may have been, was not nearly as central to Hume’s life and thought.

The relative lack of attention paid to philosophical friendships, while understandable, is unfortunate. Friendship was understood to be a key component of philosophy and the philosophical life from the very beginning, as even a cursory reading of Plato or Aristotle should remind us. The latter famously claimed that friendship is the one good without which no one would choose to live even if he possessed all other goods, and Hume and Smith clearly concurred. Hume held that “friendship is the chief joy of human life,” and Smith proclaimed that the esteem and affection of one’s friends constitutes “the chief part of human happiness.” Indeed, Hume proposed a small thought experiment to prove Aristotle’s point. “Let all the powers and elements of nature conspire to serve and obey one man,” he suggests. “Let the sun rise and set at his command: The sea and rivers roll as he pleases, and the earth furnish spontaneously whatever may be useful or agreeable to him. He will still be miserable, till you give him some one person at least, with whom he may share his happiness, and whose esteem and friendship he may enjoy.”

Aristotle divides friendships into three types: those motivated by utility, those motivated by pleasure, and—the highest and rarest of the three—those motivated by virtue or excellence. Smith draws a similar distinction in his first book, The Theory of Moral Sentiments, though he insists that the latter alone “deserve the sacred and venerable name of friendship.” Smith’s relationship with Hume represents a nearly textbook model of this kind of friendship: a stable, enduring, reciprocal bond that arises not just from serving one another’s interests or from taking pleasure in one another’s company, but also from the shared pursuit of a noble end—in their case, philosophical understanding.

An examination of Hume and Smith’s personal and intellectual relationship thus allows for a different kind of reflection on friendship than is found in the works of Plato, Aristotle, Cicero, Montaigne, Bacon, and the like. Whereas these leading philosophers of friendship tend to analyze the concept in the abstract—the different forms that friendship takes, its roots in human nature, its relationship to self-interest, to romantic love, and to justice—a consideration of Hume and Smith allows us to see that rare thing, a philosophical friendship of the very highest level in action: a case study, as it were. As my book aims to show, it is a friendship very much worth celebrating.

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