The subsequent essay will provide a brief overview on the existence of God from René Descartes through Immanuel Kant. First, section (1), examines Descartes’ proof for the existence of God. Section (2), explores G.W. Leibniz’s view on God’s existence in addition to his attempts to rectify the shortcomings of Descartes’ proofs. The remainder of the essay then examines two additional philosophers, David Hume in section (4) and Immanuel Kant in (5), who contend that God’s existence cannot be rationally proven.
As a devout Catholic, Descartes undeniably believed in God. He makes his faith clear in the letter of dedication preceding Meditations on First Philosophy. Here, Descartes writes that we must “believe in God’s existence because it is taught in the Holy Scriptures, and, conversely, that we must believe in the Holy Scriptures because they have come from God” (Descartes, 1). Nevertheless, in the beginning of the Meditations, Descartes casts doubt on everything -including religion- in his search for absolute certainty. In the Third Meditation, he doubts the existence of God before providing his first rationalistic proof for the existence of God. In offering the proof, he first questions “whether there is a God” (25). However, even though he questions God’s very existence, Descartes maintains his innate idea of God. After some deliberation, he concludes that because he has an innate idea of God, (which is not fabricated by the mind or drawn from the senses), it must be God who endowed him with his innate idea. Descartes likens his innate idea of God to the “mark of a craftsmen impressed upon his work” –similar to a stamp which says ‘Made by God’. Additionally, Descartes reasons that because he exists as a thinking thing and has an innate idea of God, God then must also exist. He explicitly states this: “I have no choice but to conclude that the mere fact of my existing is and of there being in me an idea of a most perfect being, that is God, demonstrates most evidently that God too exists” (34).
In the Fifth Meditation, Descartes offers a second, but similar proof for God’s existence. He begins this proof by asserting that a triangle, even if it does not exist anywhere in the world, “still has a certain determinate nature, essence, or form which is unchangeable and eternal” which is not fabricated by or depend on the mind (43). He then uses the triangle idea as the basis for his second proof of God’s existence. Based upon the notion of a triangle, Descartes believes that “the existence of God ought to have … some degree of certainty that truths of mathematics” have (44). Moreover, for Descartes, there is no less a “contradiction in conceiving a supremely perfect being who lacks existence than there is in conceiving a triangle whose interior angles do not sum to 180°” (Oppy). Descartes then again presumes (like he did for the proof in the Third Meditation) that because he has an idea of God, God must, therefore, exist.