The tradition of theriophily, broadly defined, persisted during the eighteenth century. One of its main proponents was Jean-Jacques Rousseau. It should be noted at the outset that Rousseau was far from a typical Enlightenment figure. His criticism of the ills of advanced civilization was more in line with primitivistic philosophy, and it is therefore no surprise to see that he expressed theriophilic opinions, since primitivism and theriophily were often conjoined. It is also no surprise that his theriophily was, like that of his predecessors, limited in the transition from theory to practice. Rousseau’s works contain many references to animals, most of them in passing, but others much more substantive and touching on central aspects of his thought. This chapter will not present a detailed survey of these sources, but will highlight only what seems important for a better understanding of key elements of Rousseau's moral attitude toward animals, and what these can teach us both about his general philosophical outlook and about general trends in the Enlightenment's consideration of this topic.

The Victorian humanitarian Henry Salt claimed at the end of the nineteenth century that “it was not until the eighteenth century, the age of enlightenment and ‘sensibility’, of which Voltaire and Rousseau were the spokesmen, that the rights of animals obtained more deliberate recognition.” Voltaire had indeed attacked the Cartesian beast-machine theory, and in general all the philosophical debates about animal mental and spiritual characteristics, singling out the cruelties of vivisection, which the view of animals as non-sentient beings helped popularize. Rousseau repeatedly addressed the issue of animals even more than Voltaire, and in the Discourse on Inequality, for example, claimed that human moral conduct was directed primarily by commiseration, not rationality. Animals, although denied human enlightenment, were nevertheless similar to human beings in their sensitive capacity, and human beings had some type of duties toward them. “It seems, in effect, that if I am obliged not to do any harm to anyone similar to me, this is less because he is a reasonable creature than because he is a sensitive one; a quality being in common among the animals and the man, it should at least give the one the right not to be maltreated unnecessarily by the other.”