This is any argument which tries to prove the existence of God based on observable things in nature. The Argument from design and the watchmaker arguments are two examples. In these kind of arguments, it is assumed that everything in nature fits so well and functions so perfectly that it must be caused by an intelligent being. In effect, one can simply look around them and see God's existence. In the Critique of Pure Reason Kant, who discussed this idea, claimed that proving the existence of God via this method is impossible.