The design argument also known as the teleological argument explains the existence of God which incorporates the Greek word ‘telos’ meaning ‘goal’ or ‘purpose’. It explores if there is a designer of things and whether the designer is God. Similarly to the cosmological argument it is an example of an a posteriori argument which means it is an argument that is based on evidence gotten by experience. This essay will seek to explain Aquinas and Paley’s version of the teleological argument. Some intelligent beings exists by whom all natural things are directed to their end; this being we all call God. Thomas Aquinas puts forward his version of the argument in his fifth way which is outlined in his work ‘Summa Theologica’. His argument is also known as the argument based on regularity. This means that he bases his argument on the fact that things in nature follow certain laws that lead to certain results. It as be summarised as follows: when you look at the natural world you can see that everything follows a natural law; If they follow natural law, the must have some goal or purpose; However, if a thing cannot think for itself it does not have any goal or purpose unless it is directed by something that can think; finally, everything in the natural world that does not think for itself is directed by something that can think, this being we call God. Aquinas uses the example of an archer shooting an arrow. Here, he implies that the arrow, an object that cannot think for itself, cannot have been shoot without an archer, a being which can think, shooting it. The arrow will be the effect of the archer (cause). It is essential to remember that Aquinas version was influence by the four causes by Aristotle however the work that is mostly linked would be Aristotle’s idea of the final cause, the ‘prime mover’. Another person who a key version which explain the teleological argument would be William Paley. His most famous argum