PHIL 110 · Metaphysics — Necessity, Contingency, and the Existence of God

About this course

The final module of the Metaphysics paper arrives at the question the whole paper has been climbing toward: is there a necessary being — something whose very nature is to exist — and can its existence be demonstrated? It is led by Thomas Aquinas, who gave the arguments their most disciplined form.

Aquinas first clears the ground with a distinction: God's existence may be self-evident in itself, but it is not self-evident to us, who do not grasp the divine essence — so it must be proved, and proved the hard way, from the world's effects rather than from the mere concept of God. That rules out the ontological argument (which Anselm and later Descartes built from the idea of a most perfect being, and which Kant answered with the claim that existence is not a real predicate). It leaves the cosmological arguments — the famous Five Ways, from motion, from causation, and from contingency to a necessary being — and the teleological argument from the order of nature, which Hume took apart in his Dialogues. Throughout, the module works in Aquinas's own manner: state the question exactly, give every objection its full strength, and grant each argument only what it has truly earned.

Because this is the last module, it gathers the paper. Hume's doubts about causation press on every causal proof; Kant marks the limits of such reasoning; and the closing distinction between contingent being and necessary being draws together threads from Parmenides, Aristotle, Leibniz, and Spinoza. The student leaves not with a verdict imposed, but able to weigh the oldest argument in metaphysics for themselves. They read Aquinas's Five Ways, Anselm's Proslogion, and Hume's Dialogues directly.