The cosmological argument: the argument from causation and contingency (Aquinas's first three Ways, the Kalam version), and the main criticisms from Hume and Russell.

What this key area is asking

The cosmological argument is the first of the three classical arguments and the clearest example of an a posteriori argument: it starts from the plain fact that the universe exists and asks what must be true for it to exist at all. You must understand the argument from causation and contingency (Aquinas's first three Ways and the Kalam version), the idea of a first cause and a necessary being, and the major criticisms from Hume and Russell, then evaluate whether it succeeds.

The argument from causation

The argument's force rests on the claim that an actual infinite regress cannot do the explanatory work: if every cause depends on a prior one and the chain never bottoms out, the existence of the chain is never explained. The first cause is therefore posited as uncaused, the terminus that explains the rest.

The Kalam version

The Kalam version is examinable as a modern restatement that focuses on the universe having a beginning, rather than on a present chain of causes. It is often paired with the claim that an actually infinite series of past events is incoherent.

The argument from contingency

The third Way is the argument from contingency: things in the world are contingent, meaning they come into and go out of existence and need not have existed. But if everything were contingent, there would at some point have been nothing, and nothing could then come from nothing, so there must be a necessary being whose existence is not contingent and which explains why contingent things exist at all. This being is identified with God.

Criticisms: Hume and Russell

These criticisms target the argument at its joints: the causal principle, the inference from parts to whole, and the leap from "a first cause" to "God." A strong evaluation also notes the defender's replies, that an actual infinite regress is incoherent and that a necessary being best explains contingent existence, and weighs them.

Evaluating the argument

The central evaluative point is the gap between a first cause and the God of theism. Even if the argument succeeds, it establishes at most an uncaused, necessary being or first cause; it does not on its own show that this being is personal, good, omniscient or the God of any religion. Defenders argue the necessary being must have certain attributes; critics argue the conclusion is far thinner than theism needs. A good judgement weighs whether the argument is suggestive but inconclusive, or stronger than its critics allow.

Worked example

Try this

Q1. State the three steps of the Kalam cosmological argument. [2 marks]

• Cue. Whatever begins to exist has a cause; the universe began to exist; therefore the universe has a cause.

Q2. What is the "gap" objection to the cosmological argument? [2 marks]

• Cue. Even if the argument works, it establishes at most a first or necessary cause, not the personal, good God of theism, so a further argument is needed to reach God.