Materialism and the Morale Universelle

Abstract

“Quelle notion précise,” asked the author of the Salon de 1767, “peut-on avoir du bien et du mal, du beau et du laid, du bon et du mauvais, du vrai et du faux, sans une notion préliminaire de l’homme.”¹ For Diderot an understanding of the nature of man and of his cognitive powers was the starting-point for speculation about ethics and aesthetics, and by extension about politics. He began his intellectual career under the influence of Shaftesbury as a rationalist deist, strongly inclined towards scepticism, but unable to take the final step to a radical negation of the transcendental. This philosophical limbo suited an antimetaphysician like Voltaire perfectly, but for Diderot it was a frustrating barrier to speculative thought. The Lettre sur les aveugles (1749), inspired by Condillac’s sensationalism and founded upon an implicit atheist materialism, marked the turning-point. By opting for the only fruitful alternative to Catholic theology he was able to embark upon a sustained study of the origins of human knowledge which had previously been closed to him. The first steps in the Lettre sur les aveugles are hesitant; the arguments which make the individual’s moral conscience dependent on the degree to which he is able to perceive the external world through his senses are either crude or faulty.