The friendship between David Hume and Adam Smith ¨C which lasted for more than two decades, from 1750 to 1776, the year of Hume¡¯s death ¨C is undoubtedly one of the most interesting and productive intellectual partnerships in the history of modern thought. It is somewhat surprising that it should not have received more attention from scholars.

The main reason for this neglect ¨C as Dennis C. Rasmussen explains in the introduction to his engaging The Infidel and the Professor ¨C is the scarcity of surviving historical evidence. The ¡°infidel¡± Hume and the ¡°professor¡± Smith were both ¡°averse to having their unpolished writings and their private lives made public¡±. This shared aspiration to reserve led them to destroy a large part of their personal papers and correspondence, leaving for posterity only a few, much cited, letters and the occasional recollections of acquaintances. Indeed, more than two centuries later Rasmussen admits to a sentiment of guilt for his scholarly attempt to violate their privacy.

The fact that his two protagonists were never involved in any bitter public disputes no doubt helped discourage the interest of contemporaries as well as of future generations: steady friendly relations do not on the whole attract great curiosity. But another crucial factor was the evolution of the social sciences during the 19th and 20th centuries. The transformation of what Hume called the ¡°experimental science of man¡± into a set of distinct academic disciplines has gradually imprisoned Smith and him in the separate specialist domains of, respectively, economics and philosophy.

In exploring the friendship between the two men, Rasmussen is also trying to break down these disciplinary barriers, showing how their contributions originally ranged over moral philosophy, epistemology, jurisprudence, history and political economy. And their way of thinking about the position of man within modern society was often far more global and inclusive than we now tend to find in the two disciplines that have adopted them as major representative figures.

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Rasmussen constructs his twin portraits through a series of alternating biographical chapters. Both born in Scotland ¨C Hume in Edinburgh, Smith in the small town of Kirkcaldy ¨C the two men were separated by a significant age gap (Hume was about 12 years older) and by a marked difference in temperament that dictated their respective career paths. The flamboyant and worldly Hume was unable, or unwilling, to conceal his deeply sceptical philosophical views, especially on the subject of religious belief, an attitude that soon gained him a reputation for atheism and even for immorality. The fierce hostility of the Scottish church prevented him from being appointed to any of the academic posts to which he initially aspired. As he had no family fortune to rely on, he ended up accepting a series of minor diplomatic posts on the Continent, in particular in Italy and France; more important, he became a successful independent writer, thanks to the various editions of his Essays , but especially to his greatly popular History of England (1754-1761).

Smith, on the other hand, although in fact equally critical of religious superstition and bigotry, was far more guarded in expressing his personal opinions on the subject. His prudence made it possible for him to occupy first the chair of logics, and later that of moral philosophy, at the University of Glasgow, where he had been a student. His two major works, The Theory of Moral Sentiments (1759) and the Inquiry into the Wealth of Nations (1776), grew to a large extent from material and discussions developed during the years of his teaching activity.

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Today, Smith¡¯s cautious attitude towards academic and religious authorities may seem somewhat hypocritical if not cowardly; but it is difficult for us to measure the pressure that orthodoxy could exercise upon people¡¯s lives, even in a relatively free country such as Scotland. Indeed the viciousness of some of the attacks against those deemed to be ¡°free thinkers¡± was well up to the level of contemporary hate campaigns in social media. As Rasmussen recalls, when Hume published the volumes of his History of England on the Tudors after those on the Stuarts, it was said by a critic that he wrote his works backwards, ¡°the way witches say their prayers¡±.

Smith ¡°encountered¡± Hume for the first time in the early 1740s, as a student at Balliol College, University of Oxford, when he read his controversial philosophical work, A Treatise of Human Nature, only to have the book confiscated by the academic authorities. They actually met in person in Edinburgh a few years later, probably around 1750. No details of this first meeting are known, but the two continued to keep in touch, exchanging letters and manuscripts and occasionally making the 13-hour journey that separated Glasgow, where Smith lived, from Edinburgh, Hume¡¯s favourite place of residence.

Over the past few decades, much has been written about the distinctive cultural context represented by the Scottish Enlightenment, with its unique combination of provincial settings and cosmopolitan ambitions, of political frustration after the loss of independence and extraordinary intellectual achievement. Hume and Smith, with their shared concerns about the nature of modern commercial society, about the moral consequences of secularisation and economic growth, were clearly a product of this distinctive background. As their reputation spread within European intellectual circles, they gained access to London society and to Parisian salons, such as that of Madame de Boufflers. There, they tasted the pleasures of literary fame, meeting prominent intellectuals such as Voltaire, Diderot, Rousseau and the Physiocrats.

Both seem to have been at ease in such fashionable settings, if in a rather different style: Hume witty and flirtatious, Smith retiring and famously absent-minded (one account describes him, deep in meditation, dipping a slice of buttered toast into his hostess¡¯ teapot). Yet they remained faithful to their roots and finally returned to Scotland.

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Like other scholars who have addressed the issue before him, Rasmussen can only offer plausible conjectures about the crucial questions raised by the collaboration between the two authors. How and where exactly did Hume and Smith influence one another? Was The Theory of Moral Sentiments an indirect attempt on Smith¡¯s part to correct some of Hume¡¯s assumptions about the dynamics of selfishness and altruism in individual human responses? To what extent can we say that The Wealth of Nations was based upon Hume¡¯s philosophical intuitions about men¡¯s greed and craving for social approval? Did Smith himself play any role in the shaping of Hume¡¯s reflections on the political and economic prospects of post-revolutionary British society?

What his book does offer, on the other hand, is a clearer, more exhaustive picture of the common ground that existed between the two thinkers, a map of the intersections, echoes and mirroring perspectives that connect their works. The Infidel and the Professor is written in a style that makes it accessible to non-specialists, who can discover through it the story of two exceptional and very engaging personalities. But it is also of interest for those who are already familiar with Hume¡¯s and Smith¡¯s lives and works, as it allows us to see them as part of a collective intellectual project. Above all, it reminds us of what the social sciences were originally meant to be: a broad critical reflection on the condition of human beings exposed to the bewildering transformations that modernity brought to their lives.

Biancamaria Fontana is professor of the history of political thought at the University of Lausanne.

The Infidel and the Professor: David Hume, Adam Smith, and the Friendship That Shaped Modern Thought
By Dennis C. Rasmussen
Princeton University Press
336pp, ?24.95
ISBN 9780691177014
Published 13 September 2017

The author

Dennis Rasmussen, associate professor of political science at Tufts University, was born in St Louis, Missouri, but spent his childhood in Michigan. He was an undergraduate at Michigan State University¡¯s James Madison College, which offered, he says, ¡°the close faculty-student interaction of a liberal arts college along with the resources of a major research university¡±. Inspirational teaching spurred him to pursue an academic career, so he went on to a PhD in political theory at Duke University, where he is grateful to the diversity of the faculty for exposing him to a wide ¡°variety of viewpoints and approaches¡±.

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Already the author of two other books in which David Hume and Adam Smith are central figures, Rasmussen was ¡°eager to explore their lives and their relationship in greater depth¡­It is remarkable that two thinkers of the stature of Hume and Smith were best friends for most of their adult lives ¨C indeed, I argue that theirs was the greatest of all philosophical friendships ¨C and equally remarkable that no book had been written on their personal or intellectual relationship¡­I have always enjoyed reading books that combine biography with philosophy, particularly those that seek to tell a story in an accessible and entertaining way, so I decided to try my hand at writing one.¡±

Asked about the importance of the Enlightenment in the current political climate, Rasmussen responds that it ¡°has never, at least in my lifetime, been more ¡®relevant¡¯. I would not want to suggest that the thinkers of the 18th century somehow possessed the hidden keys to solving all of today¡¯s problems, but I do think that the works of Hume and Smith, in particular, have a number of important lessons to teach us regarding the virtues of open-mindedness and intellectual humility, moderation and pragmatism, civility and respect, and the importance of relying on concrete evidence rather than gut instinct or abstract ideology.¡±

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Matthew Reisz