The ontological, cosmological and teleological (design) arguments for the existence of God, including the forms given by Anselm, Aquinas and Paley, and the main criticisms of each.

What this dot point is asking

AQA wants you to explain the three classical arguments for God's existence: the ontological argument (a priori, from the definition of God), the cosmological argument (a posteriori, from the existence of the universe) and the teleological or design argument (a posteriori, from order and purpose). You must give the key thinkers' versions and evaluate the main criticisms.

The ontological argument

Anselm (in the Proslogion) defines God as "that than which nothing greater can be conceived". A being that exists in reality is greater than one that exists only in the mind, so the greatest conceivable being must exist in reality, otherwise it would not be the greatest. In his second form, Anselm argues that God has necessary existence (God cannot be conceived not to exist).

Criticisms. Gaunilo's "perfect island" parody says that by Anselm's logic the most perfect conceivable island would have to exist, which is absurd, so you cannot define things into existence. Anselm replies that the argument works only for a being whose non-existence is impossible (a necessary being), not for contingent things like islands. Kant's more decisive objection is that existence is not a predicate: saying a thing exists adds nothing to the concept of the thing (a hundred real coins contain no more in their concept than a hundred imagined coins), so a "God who exists" is not a greater concept, merely a claim that the concept is instantiated. Existence is therefore not a perfection that the definition of God could entail.

The cosmological argument

The arguments rest on the Principle of Sufficient Reason (everything must have an explanation) and on the claim that an actual infinite regress of causes is impossible, so the chain must terminate in something that does not itself depend on another.

Criticisms. Hume questions why the universe needs a cause at all, and whether from a finite effect we can validly infer a single, infinite, perfect God rather than many lesser causes. In his radio debate with Copleston, Russell denied the Principle of Sufficient Reason outright: "the universe is just there, and that's all", a brute fact needing no explanation. The fallacy of composition is alleged: what is true of each part (each event has a cause) need not be true of the whole series, just as every player having a mother does not mean the whole team has a mother. Modern cosmology also offers alternatives such as quantum fluctuations or a self-contained universe.

The teleological (design) argument

Paley's watch analogy: finding a watch on a heath, its intricate parts working together for a purpose force the conclusion that it was designed, even if we never saw it made and even if it is imperfect or sometimes goes wrong. By analogy, the order, regularity and "fitness" of parts in nature (the eye, the rotation of the planets) imply a divine designer. This is design qua purpose (parts working for an end) and design qua regularity (the order of the cosmos). F. R. Tennant's later anthropic argument (the universe is finely tuned for life) and aesthetic argument (beauty exceeds what survival requires) update the case.

Criticisms. Hume (anticipating Paley) attacks the analogy itself: the universe is not much like a machine, so the inference is weak; like effects need not have like causes; the world could be the work of many gods, an apprentice god, or an infant deity; and the problem of evil tells against a perfect designer. The decisive modern objection is Darwin's theory of natural selection, which explains the appearance of design as the cumulative result of random variation and survival, so that, as Dawkins puts it, the only watchmaker in nature is the blind forces of physics.