 According to the Innate Concept thesis, some of our concepts have not been gained from experience. They are instead part of our rational make-up, and experience simply triggers a process by which we consciously grasp them. The main concern motivating the rationalist should be familiar by now: the content of some concepts seems to outstrip anything we could have gained from experience. An example of this reasoning is presented by Descartes in the Meditations. Although he sometimes seems committed to the view that all our ideas are innate (Adams 1975 and Gotham 2002), he there classifies our ideas as adventitious, invented by us, and innate. Adventitious ideas, such as a sensation of heat, are gained directly through sense experience. Ideas invented by us, such as our idea of a hippogriff, are created by us from other ideas we possess. Innate ideas, such as our ideas of God, of extended matter, of substance, and of a perfect triangle, are placed in our minds by God at creation. Consider Descartes’s argument that our concept of God, as an infinitely perfect being, is innate. Our concept of God is not directly gained in experience, as particular tastes, sensations, and mental images might be. Its content is beyond what we could ever construct by applying available mental operations to what experience directly provides. From experience, we can gain the concept of a being with finite amounts of various perfections, one, for example, that is finitely knowledgeable, powerful and good. We cannot however move from these empirical concepts to the concept of a being of infinite perfection. (“I must not think that, just as my conceptions of rest and darkness are arrived at by negating movement and light, so my perception of the infinite is arrived at not by means of a true idea but by merely negating the finite,” Third Meditation, p. 94.) Descartes supplements this argument by another. Not only is the content of our concept of God beyond what experience can provide, the concept is a prerequisite for our employment of the concept of finite perfection gained from experience. (“My perception of the infinite, that is God, is in some way prior to my perception of the finite, that is myself. For how could I understand that I doubted or desired—that is lacked something—and that I was not wholly perfect, unless there were in me some idea of a more perfect being which enabled me to recognize my own defects by comparison,” Third Meditation, p. 94).