Géraud de Cordemoy was born in a family of ancient nobility coming from Auvergne (from the town of Royat). He was the third of four children. His father was a master in arts at the University of Paris named Géraud de Cordemoy who died when he was nine years old. His mother was named Nicole de Cordemoy. As for Géraud, he was a private tutor and a linguist and practised as a lawyer.
Géraud de Cordemoy used to haunt the philosophical circles of the capital; he made acquaintance with Emmanuel Maignan and Jacques Rohault. A friend and a protégé of Bossuet who admired Descartes too, Géraud de Cordemoy was appointed lecteur (tutor) to the Dauphin (son of King Louis XIV), at the same time as Fléchier. He was elected a member of Académie française in 1675.
Cordemoy is known primarily for having rethought the Cartesian theory of causality, introducing the notion of “occasional cause” within a system of thought which remains essentially Cartesian. He was, alongside Arnold Geulincx and Louis de La Forge, the founder of what is called “occasionalism”. Body and soul are distinct by essence, their combination is occasional, and it is God who allows that the will to move my arm, for example, is translated into a movement. My will is an occasional cause of the movement of my arm, God is the real cause of it. What is true for the body-an individual constituted by the distinct combination of body and soul- is true for every body in the universe. God is the real and universal cause of every movement.
By body, Cordemoy means the ultimate components of matter. Using a judicial figure of speech, he shows that the body, in law a person, in physics an ultimate component of matter, is indivisible. Never mentioning atomism, with that theory he comes close to the followers of Gassendi and to the free thinkers, the so-called Libertines. In his work “Le discernement du corps et de l’âme” (Discrimination between body and soul) he develops such thoughts which were criticized at that time by the followers of Descartes.
In his work Discours physique de la parole (Physical Discourse on Speech), he asks himself the following question: “How can I, as a thinking being, be certain that the human beings who surround me are also thinking beings, and not simple automatons? The problem is considered at the end of the sixth speech on discrimination between body and soul. It is the word as a vehicle of the thought which will enable me to know the existence of other individuals who are endowed with a soul like me.” In a more original way, in his work “Traité physique de la parole”( physical treatise of the word)- a variation of the previous title - he develops the notion that no motivated relation between the material sign and the expressed idea exists, as much as no real relation exists between body and soul. The word represents the opportunity for sign and meaning to meet, so far as if the soul hadn’t the use of the articulated body to produce sign, it would communicate in a much more immediate way from soul to soul, without having to go through the institution of the sign.