The cosmological argument has its roots in the writings of Plato and Aristotle, but is most associated with Aquinas’ first, second and third ways to demonstrate God’s existence and today with William Lane Craig’s Kalam argument.  While cosmological arguments see God as the “sufficient reason” for the universe, overall, they do not provide a sufficient explanation for the existence of God.

Firstly, Leibniz’ version of the cosmological argument saw God as the “sufficient reason” for the universe. God is needed, he reasoned, to explain why there is anything at all. In “The Existence of God” Richard Swinburne writes how this is the most basic and persuasive argument for God’s existence.  Leibniz’ reasoning built on Aquinas’ third way, which started with the premises that everything in the universe is contingent and that something cannot come from nothing, concluding that there must be a necessary being – a being which exists because of itself and cannot not exist – to explain the existence of everything else. Yet Kant rejected this line of argument in the introduction to his “Critique of Pure Reason”, pointing out that as everything that we experience exists contingently, necessary existence is not something we can posit or discuss.  For Kant, to exist is to exist contingently and to be capable of non-existence… the idea of necessary existence is contradictory and impossible. While there are those who reject Kant’s argument and indeed his whole worldview, such as Willard Quine and Charles Hartshorne, it remains the dominant position in philosophy. While Kant may not have shown that necessary existence is impossible, his observation that it falls outside the scope of our experience strongly supports that conclusion.  This shows that God is not needed to be the necessary explanation for the universe we experience.

Secondly, as David Hume observed through his character Philo in Dialogues Concerning Natural Religion, despite being presented as deductive proofs for God’s existence cosmological arguments fail because there is no way to show that their premises are true. For example, Aquinas starts his first way with the premises that everything in the universe is moved and that things can’t move themselves, concluding that there must therefore be a Prime Mover and that this is what everybody calls God. As Hume pointed out, there is no way to know if everything in the universe is moved or that no thing can move itself because our experience of the universe is too limited to support such sweeping claims.  It is possible that while things in the universe are moved and must be moved by other things, the universe itself could be unmoving and/or self-moving.  As Bertrand Russell later asked, why should not the universe itself be considered a “brute fact”?  Although Big Bang theory seems to have falsified the idea that the Universe could be considered a “brute fact,” in other ways science supports Hume’s scepticism, finding that sub-atomic particles like Quarks do not follow standard laws of causation and logic and forcing William Lane Craig to use more limited premises in his Kalam argument than Aquinas did in his Cosmological Argument.  Craig reasons that since “everything that begins to exist must have a cause” and “the universe began to exist” it follows that “the universe must have a cause”.  Although it strategically stops short of concluding that the cause of the universe is “what everybody calls God” – leaving this for people to infer – Craig’s argument seems persuasive in the context of a layman’s understanding of the standard model of Physics. Yet, Stephen Hawking criticised his argument for assuming that causation must or even could apply where there is no time or space at and before the Big Bang. This shows that the cosmological argument fails to demonstrate God’s existence

On the other hand, other versions of the cosmological argument have been presented as inductive or even abductive arguments, suggesting that God is the most probable explanation for many observations of movement, causation, contingency and other forms of order in the universe.  This approach acknowledges that science could provide natural explanations for these phenomena, but dismisses these as less probable than the simple, elegant explanation provided in God. Yet, while the prime mover, uncaused cause or necessary being supported by Aquinas’ ways seems   to be a simpler explanation than the complex natural accounts presented by science, as Hume pointed out, the prime mover, if such there is, would be very far from being “what everybody calls God.”  In terms of prime movers, uncaused causes or necessary beings, there could be several for all we know and it/they would hardly need to be personal, immanent or good.  Also, the God of the Bible is nothing if not a complex character, being possessed of many characteristics outside the scope of those possessed by the prime mover, so that Richard Dawkins was right to reject the claim that “God” could ever be a simpler explanation in “The God Delusion”.  While Aquinas did attempt to show how the prime mover, uncaused cause and necessary being demonstrated by the cosmological argument was really the God of Christianity, these explanations were outside the scope of the cosmological arguments and unconvincing.  For example, Aquinas claimed that because God is the prime mover, uncaused cause and necessary being He must be timeless-eternal and outside the universe.  It follows that divine attributes like power, knowledge or goodness must be understood as analogies when describing God. Yet Aquinas’ classical theism is unconvincing because although it attempts to provide a philosophical justification for believing that “God” exists – not least through the cosmological argument – this justification is flawed and comes at the price of undermining both the Bible and Christian Doctrine as sources of knowledge about God.  This shows that inductive or abductive versions of the cosmological argument are no more useful as explanations for God’s existence than deductive versions.

Further, all versions of the cosmological argument are part of Natural Theology, the attempt to explain that and how God exists using reason. Natural Theology has long been controversial within Christianity, because it assumes that human beings can discover God and potentially salvation for themselves without God’s grace, which idea was dismissed by St Paul (e.g. Ephesians 2:8) and later made a heresy because of St Augustine’s theological arguments.  It follows that for most Christians Natural Theology cannot provide sufficient knowledge of God’s existence or concerning God’s nature for human beings to attain salvation apart from God’s grace.  Instead, Christians must rely on Revealed Theology, such as through Scripture, Jesus and/or personal religious experience, to demonstrate God’s existence, nature and will.  In one way, this makes sense of the cosmological arguments’ failure to show that God is the necessary or even the most probable explanation of the universe and of the disjunct between the attributes of the prime mover and the God of the Bible.  It could be that the cosmological argument, and wider Natural Theology, provides only an indication that God exists, showing that faith is rational and that atheists are as St Paul put it “without excuse”, while maintaining the necessity of revelation and grace for salvation. Yet it seems terribly convenient that Christian doctrine should so cover for the failure of Natural Theology and the cosmological argument. St Paul and St Augustine would both have been aware of versions of the cosmological argument in the work of Plato and Aristotle and that these arguments are not sufficient explanations for the God of Christianity.  Could their theological arguments have been pragmatic rather than principled in their attempt to sideline reason in favour of revelation?

In conclusion, the cosmological argument does not provide a sufficient explanation for the existence of God. None of the versions of the argument succeed in demonstrating God’s existence. Deductive versions rely on uncertain premises and don’t contain the full conclusion of the Christian God’s existence. Inductive and abductive versions fail to establish that “God” is a simpler explanation of the universe than natural explanations provided by science.  Also, theological attempts to explain why Natural Theology should fail are unconvincing.