St Thomas Aquinas presents five ways of demonstrating God’s existence based on observation in his Summa Theologica (1,2,3).  The first four of these ways are Cosmological arguments, reasoning from observations of movement, efficient causation, contingency and grades of perfection in the universe a posteriori to the conclusion that God as a Prime Mover, uncaused cause, necessary being and supreme perfection must exist.  The fifth way is a teleological argument, reasoning from observation of order and purpose (teleology) in the universe a posteriori to the existence of an intelligent designer “which is what everybody calls God.”  Clearly, Aquinas saw both Cosmological and Teleological Arguments as persuasive arguments for God’s existence, however the Teleological Argument offers better support to the God of Christian worship than the Cosmological Argument does.

David Hume criticised cosmological arguments in his Dialogues Concerning Natural Religion (1779).  His character Philo pointed out that it is based on limited observations of the universe.  For all we know there might be uncaused things out there… as indeed Quantum Physics and Particle Physics has since shown to be the case.  Further, the argument is based on the fallacy of composition, the assumption that just because the parts of the universe have a cause that the whole universe must have a cause.  As Bertrand Russell later pointed out; just because all men have mothers doesn’t mean that the human race has a mother, it could be that the universe is a “brute fact”.  Hume’s criticisms of the cosmological argument are difficult to overcome.  While it is fair to say that Hume’s claims about the limitations of human observations as the basis for knowledge about natural laws are just as much of a problem for science as they are for religion, his other criticisms hit hard.  In truth, the universe might, for all we know, be uncaused or be its own cause.  It is fair to ask why what is true of the part should also have to be true of the whole.  Although William Lane Craig argues that the cosmological argument – at least in his own Kalam version, which stops short of concluding that the Prime Mover is “what everybody calls God” – is the best support for the reasonableness of faith, his claims about the impossibility of an actual infinite and about the Big Bang theory needing a cause have been shown to be mistaken by critics such as Erik Sotnak and Stephen Hawking.  While the cosmological argument might superficially seem to be supported by Big Bang theory, in reality Cosmology shows that the idea of causation cannot apply outside the space-time matrix of our universe.  While it seems incredible, as Terry Pratchett quipped, science proposes that “in the beginning there was nothing, which exploded.” It is clear, therefore, that the cosmological argument is not persuasive. 

Hume’s character Philo also attacked the teleological argument in the Dialogues, criticising the tendency to make the argument using inappropriate analogies and pointing out apparent imperfections in the design of the universe, which might undermine the idea that the designer would be perfect.  Later, both Charles Darwin and JS Mill pointed out the brutality in nature and reasoning that an Ichneumon wasp could not have been designed by the God of Christianity.

“Nearly all the things which men are hanged or imprisoned for doing to one another are nature’s everyday performances.”  Mill: Three Essays on Religion

Nevertheless, these critics all failed to exclude the possibility that the universe could be designed to contain evil for some morally sufficient reason.  As St. Augustine argued, it could be that natural evil in the world is a just punishment for sin.  Moral evil could be the necessary bi-product of human freedom.  Evil does not necessarily undermine the claim that the universe was designed by God.  Alternatively, as John Hick argued, suffering could be positively created by God to afford the opportunity for “soul-making” with any injustices being accounted for through an afterlife.  Further, there are versions of the teleological argument which do not rely on spurious analogies – such as FR Tennant’s aesthetic argument and anthropic principle.  These are more persuasive than the cosmological argument.  Hume’s criticisms fall short of undermining Tennant’s claim that God is needed to explain beauty and human consciousness in the universe and evolution through natural selection fails to explain these aspects of the universe adequately either.  Modern Intelligent Design arguments – such as those proposed by Michael Behe from irreducible complexity and by William Dembski from specified complexity – show that evolution cannot provide the complete explanation that atheists like Richard Dawkins claim it can.  While Paley’s argument in Natural Theology can be rightly criticised for its use of the famous watchmaker analogy, its appeal to our incredulity at the scientific claim that all this could have arisen by chance is powerful.  To accept that evolution through natural selection can provide a complete explanation of the universe and that there is no intelligence guiding it is difficult to accept.  Take the Japanese puffer-fish… can evolution really account for the extent of the intricacy and beauty of its designs?  It is clear, therefore, that the teleological argument is more persuasive than the cosmological argument.

In addition, even if the cosmological argument was persuasive, it would only serve to demonstrate the existence of a Prime Mover, an uncaused cause, a necessary being outside time and space.  It is not easy to see how this being could be the God of Christian worship.  Aristotle stopped short of claiming that the Prime Mover could be a God in any normal sense, its power being limited to supporting the existence of all contingent things and its goodness being limited to being fully actualised and containing no potential. How could a God who is outside time and space act to create the universe when there could be no time before during or after his action and when there would be no space to differentiate the creation from the creator?  Both human understanding and the language which tries to communicate it struggles to cope with objects outside the space-time matrix which bounds our experience.  It might, of course, be fair to say that human understanding and language cannot expect to be able to comprehend or describe God.  Yet, without the ability to claim that God exists, that God is the all-powerful creator and that God is good with some content, it is difficult to see how Religion could prosper.  St. Thomas Aquinas attempted to show how human language could be used to describe God in positive terms as analogies, but even he admitted that he content of attributes such as goodness must needs be limited and cannot be understood in the same way as human goodness.  The teleological argument, by contrast, does not rely on locating God outside time and space.  As the intelligent designer, it seems likely that God would have defined the purpose of the universe from within the same logical framework which governs its operation today.  In this way, God’s power and goodness have real content, as they relate to how He created the complex order and purposiveness we can observe.  It follows that the teleological argument offers better support for the God of Christian worship than the cosmological argument does.

In conclusion, the teleological argument offers better support for the God of Christian worship than the cosmological argument does.  Clearly, the teleological argument relies on the possibility of defending God’s goodness and power against charges of creating or allowing evil and suffering, but it is still more persuasive than the cosmological argument.  Even Immanuel Kant, who rejected all the classical arguments for God’s existence in his Critique of Pure Reason, saw the age and persistence of the teleological argument as pointers to its status as the most powerful of the arguments for God’s existence.