Born in Dijon and educated at the Jesuit college of Dijon, Foucher joined the order, then left for Paris, where he attended the courses of the Faculty of Theology at the Sorbonne. He was in contact with Jacques Rohault and took part in the meetings of the latter's circle, where he criticized Descartes’ philosophy from a skeptical vantage point. He made experiments in hygrometry, of which he published several accounts. He engaged in a long polemics with Malebranche and Rohault. During Leibniz's visit to Paris from 1672 to 1676, Foucher was introduced to him; a long correspondence between the two men followed, as well as the publication, under Foucher's care, of some of Leibniz's writings in the Mémoires de l'Académie des Sciences and the Journal des Sçavans. He died in 1696, while writing a second critique of Leibniz's theory of monads.

In the Critique de la Recherche de la vérité, Foucher takes aim at Descartes for having affirmed the simplicity of the soul and the existence of necessary truths outside mathematics and theology. One cannot identify necessary truths in physics, medicine, and morals, since individuals are subject to change and their essences could be “but ideas.” Foucher criticizes Descartes’ theory of the creation of eternal truths from several perspectives. From the point of view of the liberty of God, he thinks that it is by grace, not nature, that God preserves the immutable truths. On the other hand, in terms of the principle of noncontradiction, he questions God's liberty to change the eternal truths. As for proving the necessity of the eternal truths by means of the immutability of God's will, Foucher affirms that this is “proving too much,” since the immutability might concern all creatures and thus block all of the changes in the world. On the other hand, if one were to maintain after all, in view of the free determination of God's will, that these truths are necessary by their nature and that this necessity derives from the immutability of the divine will, then one would need to suppose one possessed “the science of the existence of God, of his will, of his liberty and of his power,” which is to trespass on the domain of faith.