The Philosophers' Quarrel: Rousseau, Hume, and the Limits of Human Understanding

In 2001, David Edmonds and John Eidinow published Wittgenstein's Poker, a bestselling story of the legendary confrontation between two of the greatest philosophers of the 20th century, Ludwig Wittgenstein and Karl Popper. The authors used this brief episode to present the opposing visions firmly held by both participants, rooting their clash not in ideas but in class.

In 2006, Edmonds and Eidinow again used a meeting of two of the greatest philosophers of another age, David Hume and Jean-Jacques Rousseau, to present their contrasting conceptions of philosophy. In 1776, the Scottish Hume, returning to London after a triumphant stint as secretary at the British Embassy in Paris, brought with him the Swiss Rousseau, whose attacks on religion and government left him threatened with imprisonment in France and his native Geneva. But initial mutual delight and affection soon gave way to a public falling out that enthralled Europe.

Robert Zaretsky and John Scott retell the saga of this disastrous encounter. Although their work naturally overlaps with that of the occasionally cited Edmonds and Eidinow, there are differences. While Edmonds and Eidinow have done their homework, they are journalists by profession and cannot muster the details offered by Zaretsky and Scott, both specialists on Rousseau.

Both books introduce famous personages whose opinions bore on the reputations of the parties, but Zaretsky and Scott discuss Voltaire and, especially, James Boswell more fully than do their "rivals", and their use of sources in French is far more extensive.

Philosophically, Hume and Rousseau shared a wariness of the power of reason to yield truth or guide behaviour. Both were, then, stalwart critics of the Enlightenment surrounding them. Both were unwelcome in their native or adopted lands, although Hume feared only ostracism, never imprisonment. Both targeted religion above all - Hume the Calvinism of his homeland, Rousseau likewise the Calvinism founded in his birthplace, and also the Catholicism of France.

Their philosophies were nevertheless as opposed as can be. Hume, whose works consist of arguments of the most acute kind, believed that reason, while the "slave" of the "passions", was not the opponent of emotion. He maintained that humans are directed more by their psychology than by reasoning, but he did not oppose reason or progress.

Rousseau, whose disparate philosophical works consist of autobiography, epistles, fiction and social tracts, believed that humanity in its original state was pristine and had been corrupted ever since by private property and learning. He did advocate the enlistment of reason against superstition, but found the ideal human state to be the state of nature, not the state of civilisation. Whereas the bon vivant Hume thrived in the city, the reclusive Rousseau sought the countryside.

Zaretsky and Scott, like their counterparts, do not collapse ideas into personalities. Instead, they interpose ideas with events. They note the parallel between what Rousseau preached and what he practised - for example, his stalwart refusal almost to the end to accept a pension from a monarch on the grounds that his independence would be compromised. At the same time, they note disparities between Rousseau's pronouncements and his own behaviour - for example, his demand for solitude undercut by his straining to be noticed at the theatre.

Conversely, they try to match Hume's reliance on empirical evidence with his inability to fathom Rousseau's accusation of betrayal: "while Rousseau insisted on reasons the heart alone can know, Hume stubbornly maintained that such reasons must withstand appeal to available facts and public testimony". But they also note, as did Hume himself, episodes in which he, too, was ruled by more than "the evidence".

Zaretsky and Scott do not psychologise their subjects. Labelling Rousseau paranoid is not venturing beyond the obvious. The authors stick to the descriptive level, which they nevertheless flesh out in delightful detail.

For Zaretsky and Scott, "neither man was able, in the end, to credit the other's account of understanding and self-understanding". The limits referred to in their subtitle were both personal and philosophical. This tale of the coming together of extraordinary thinkers who proved unable to fathom each other is told with exceptional verve.