The acrimonious breakup of the short-lived friendship of Rousseau and Hume has often been studied, most recently in Rousseau's Dog: Two Great Thinkers at War in the Age of Enlightenment by David Edmonds and John Eidenow. Zaretsky and Scott's new examination does not add to what is known about the episode, since they, too, draw from the usual limited sources: the correspondence of the protagonists and their contemporaries, Hume's account, and the observations of biographers and commentators. But they do offer fresh insights in musing on the character and quirks of these extraordinary thinkers and in asking what their quarrel reveals about the varying perspectives lurking behind the reductionist label, the “Age of Reason.”

The dissolution was especially troubling at the time because, as they suggest, philosophy was thought to be a way of life, as it had been in classical times, and not the detached academic pursuit it has since become. Rousseau's well-known alienation from Diderot and the other Parisian philosophes was bad enough, but the break with Hume seemed to show that the life of the mind could not provide a humanistic alternative to the sense of community offered by the Age of Faith that so many were trying to escape.

The record is well established. The rupture came after Rousseau got into trouble (not for the first or last time) and Hume came to the rescue. In February 1765, Rousseau published a polemical attack on the ruling council of Geneva for violating his native city's republican constitution. In it he repeated the religiously heterodox view he had expressed in Émile. Encouraged by Voltaire, who hated Rousseau as a kind of Enlightenment apostate but cynically accused him of irreligion, the political leaders Rousseau targeted issued a declaration condemning the book. The citizens of Geneva, where The Social Contract and Émile had previously been burned, heartily agreed. When this anathema was endorsed by the pastor in the village where Rousseau had been living, he felt he had to leave Swiss territory. A woman admirer contacted Hume, who expressed great respect for Rousseau and wrote to assure him of a warm welcome in England. Rousseau agreed to take the asylum he was offered, provided only he could bring his dog Sultan and Thérèse Le Vasseur, his mistress and housekeeper. After arriving in London in January of 1766, Rousseau thanked Hume in his own uninhibited fashion, at one point apologizing for reproaching him by suddenly sitting himself on the knee of the reserved Scot, kissing him, and covering his face with tears. Hume not only arranged for Rousseau to stay at nominal expense in a country home belonging to a wealthy acquaintance, but was also making progress in trying to get him a royal pension. Soon, however, Rousseau turned on his benefactor, accusing him of orchestrating attacks in the press and among his friends, and of slyly maneuvering to dishonor him. Later, in the Confessions, Rousseau referred to the contretemps by claiming that he had deliberately been driven into exile and delivered to his enemies. Hume, who had ignored an earlier warning from Baron d'Holbach that in befriending Rousseau he was nursing a viper in his bosom, reacted with astonishment, telling friends that he thought Rousseau “absolutely lunatic.” Against advice from colleagues (including Adam Smith) who urged him to suffer in silence, Hume rushed to publish an account of what had transpired, quoting their correspondence, and it soon became a cause célèbre in the salons of Paris. As a result, Zaretsky and Scott nicely observe, “the querelle became an affaire.”

Zaretsky and Scott point out that although Hume and Rousseau made an odd couple in terms of personality, they shared an intellectual affinity and were both suspected of unorthodoxy by their Calvinist brethren. In contending that reason was the instrument of sentiment, they stood against the central rallying point of the age, as defined by philosophers in the mainstream. Ultimately, Hume contended, reason was “the slave of the passions.” Rousseau went so far as to say that “the thinking man is a depraved animal.” Both were hounded by religious fanatics for their critical view of dogmatic religion and their advocacy of toleration.

Otherwise, however, they were very different. Hume delighted in the conversational jousts of the salons, where he was called “le Bon David.” He wrote two rigorously logical tracts on epistemology and the origin of moral sentiments, as well as a history of England. Although he was skeptical of the powers of reasoning, he was an empiricist and welcomed the progress of the arts and sciences. Rousseau loathed the artifice and babble of polite society and sought solitude in the wild where he could botanize and daydream. He wrote a novel that launched the Romantic movement and argued that the vaunted advances in civilization had only removed man from the simplicity and authenticity of nature. These differences in the realm of ideas expressed themselves in contrasting attitudes and behavior. Hume was coolly deliberative and diffident; Rousseau, hotly emotional and temperamental: in themselves, they were the embodiment of the clash between reason and passion.

This much of the story is told very well in this illuminating study. What is missing is an attempt to link the intellectual and moral perspectives of Rousseau and Hume to their political theories. Hume is often considered a utilitarian because he sought to show that moral rules derive from self-interest. Unlike the later philosophical radicals, however, he was a conservative utilitarian, who contended that the very idea of justice derived from the institution of property. His “Idea of the Perfect Commonwealth,” Frederick M. Watkins remarked, “rests on the belief that political justice can best be attained in a country where the monopoly of political power is exercised by men with substantial property qualifications” (Hume: Theory of Politics [Austin: University of Texas Press, 1953], xvii). Rousseau blazed a far more egalitarian path when he showed that people can be at the same time ruled and free if they rule themselves. Is there some connection between these divergent political views and their philosophies and ways of life? Perhaps not, but the question is worth considering in the glaring light of their brief but meteoric encounter.