The Design argument has two parts
Design in respect of regularity
Design in respect of purpose
Regularity
This looks at design in terms of regularity in the universe – from this it may be deduced that there is a designer. Thomas Aquinas’ fifth way makes this point. Natural bodies act in a regular fashion to accomplish their end. An arrow always works in the same way. It flies towards its target, but in order to do so it requires an archer to fire it.
John Wisdom’s parable of the gardener. One of the explorers sees order amd regularity in the garden. The plants could not have been arranged as they are without a gardener. Despite the fact that no gardener actually appears, the evidence suggests to him that there is a gardener who tends the plot.
Even William Paley used evidence from Newton’s laws of motion and gravity to suggest that there is design in the universe with the rotation of the planets etc. An external agent must have imposed such order.
Purpose
The obvious one to go for is Paley’s tale of the watch. How it was found by a traveller and from it he deduced that there had to be a watchmaker. The mechanism of the watch suggested that it had a purpose. The dials and cogs were not placed there at random. The object had a purpose – to tell the time. There also had to be a designer who had deliberately put the thing together. 
Paley had another illustration from the world of human anatomy. He concentrated on the complex nature of the human eye. Such a device which lacked its own intelligence must have been specifically designed for the purpose of sight. Therefore there had to be a designer.
Before you leave Paley look closely at his dates 1743 – 1805
The Opponents
Charles Darwin 1809 – 1882
1.Natural selection is a very important challenge to the teleological argument. It provides an alternative way to Paley to explain why there is order and regularity in the world. The irregular and the dysfunctional simply died out.
2. Darwin’s theories can be checked by scientific research.
3. Paley’s argument depends on the model provided by creation narratives in Genesis – that the world was created in a static state with no hint of development such as is envisaged by evolution. Once the Genesis accounts are seen to be unhistorical and unscientific, much of what Paley said can be challenged.
David Hume 1711-1776
Remember that Hume lived and wrote his works before Paley. He was responding to the teleogical argument of people like Plato, Aquinas and Isaac Newton. He could never have read Paley. What is more surprising is that Paley doesn’t seem to have been affected by the writings of David Hume.
Hume presents his views in his work Dialogues. Here three characters Philo, Cleanthes and Demea are discussing the issue. It is probably that it is Philo who represents the ideas of Hume.
1. Humans do not have enough experience of world creators to conclude that there is only one designer.
2. If the argument was successful it might point to a designer of the universe, but why should this be the God of Christianity or Judaism?
3. It is in fact unlikely to be God, because there is so much evil in the world and things go wrong. Surely a God would not allow this.
4. Hume pointed out that the model did not fit. The world is a complex machine and complex machines have more than one designer. Many people contribute to the manufacure of such a machine. The idea of God does not fit.
5 In fact Hume doubted if the world should be compared with a machine at all, it is more like something which grows and develops of its own accord – eg vegetable.
John Stuart Mill 1806 – 1873
1. Mill was horrified by the fact that within the world of nature there is evidence of cruelty. Wild animals kill each other, tear each other to pieces for food,freeze to death and die of starvation or lack of water. How could a benevolent God allow such cruelties in the animal kingdom.
2. Nature’s ways were sometimes reigns of terror, death by hurricane, famine or disease. These aspects of “natural evil” in Mill’s eyes counted agains the idea of a good God.
3. He also believed that there was more misfortune in the world than good. In the end evil seems to win.
4. He found the idea that evil was intended to produce virtuous people unacceptable. Even when the church taught that a reward in heaven awaited those who suffered needlessly. For him this meant that the world could be unjust and unfair. This could not be described as the work of a benevolent designer.
