By the mid-eighteenth century, the question of man and animal had been the spotlight of metaphysics France since Descartes had re-opened the topic a hundred years before. At that time, the issue served to reinforce the Cartesian doctrine of dualism. Dualism held that man was comprised of two separate and distinct substances, body and soul. Generally, philosophical consensus, following Descartes, held that animals were machines or automata. Animals were bodies without souls, while the human mechanism was, on the other hand, inhabited by a spirit, an immortal essence, that was the seat of man's reason and his guiding moral force. (1) The sensualist revolution triggered by Locke brought this idea into question. Locke allowed for the possibility of thinking matter. (2) This was a philosophical bombshell that caused much discussion. If indeed matter could think, what happened to the human soul? And if matter thought, did that not mean that animals could reason just as man did? (3) Additionally, what happened to man's unique moral capacity and his immortality, of which reason was but the reflection? More than just an anthropological issue, the question of man and animal was one of deep theological, moral and metaphysical value. It is not surprising that Etienne Bonnot, abbe de Condillac (17141780) would address the question. As a French Enlightenment thinker, Condillac is a priori indebted to Descartes. At the same rime, he is a disciple of Locke's--in fact, the first English translation of Condillac's Essai sur l'origine des connaissances humaines (1746), bears the subtitle A Supplement to Mr. Locke's Essay on the Human Understanding. (4) Condillac is undoubtedly best known for his writings on language and philosophical sensualism. All of his works, from the Essai through his Logique (1780), deal with sensation, communication and mind. They examine human understanding, explore individual and societal progress and attempt to define mankind itself. It is the definition of mankind that dominates Condillac's major contribution to the man and animal debate, the Traite des animaux (1755). The focus of the present study is Condillac's treatment of man and animal the Traite des animaux. This paper will draw on other works to clarify relevant points regarding language and the mind. Condillac's treatment of man and animal will be examined as it relates to three primary questions. The first is the conflation of language, reason, and morality. The second is the consideration of human and animal capacities for language and thought. The third is the issue of theoretical or linguistically derived knowledge of God and morality, which, for Condillac, sets man and his soul apart from the beasts. In analyzing these questions, I shall demonstrate that language, reason and morality are inseparable for Condillac; that from a cognitive-linguistic stand-point, he leaves the division between man and animal vague and fluid; and that due to this fluidity, the traditional distinction between man and animal based Cartesian dualism and illustrated by moral agency is inherently contradictory. Condillac's contribution to linguistics is well documented, and has been explored quite throughly. But his contributions to philosophy and the history of ideas, beyond his development of Locke's sensualism, have been far less noted, and much more could be said. For Condillac, while not a popular writer, had a strong influence on the writing of many of the eighteenth-century philosophes. In terms of Condillac's contribution to the history of ideas, modern critics can largely be broken into two camps. Some historians see the Traite des animaux as a work which affirms Condillac's religious orthodoxy, while others see him as an anthropological ground-breaker, and a subversive philosophe. Isabel Knight, for example, emphasizes that in the Traite des animaux ... Condillac asserted the compatibility of his philosophy with religion. …