For much of its history, Christianity has been concerned with the question of whether God’s existence can be established rationally (i.e., by reason alone or by reason informed by sense experience) or through religious experience or revelation or instead must be accepted as a matter of faith. An argument from design, or teleological argument, is an argument for the existence of God. According to one version, the universe as a whole is like a machine; machines have intelligent designers; like effects have like causes; therefore, the universe as a whole has an intelligent designer, which is God. The argument was propounded by medieval Christian thinkers, especially St. Thomas Aquinas, and was developed in great detail in the 17th and 18th centuries by writers such as Samuel Clarke and William Paley, and also in the works of Islamic philosophers such as Averroes. Later philosophers challenged the idea, replacing the notion of purpose with cause, and scientific theories helped refute the argument, like the theory of evolution.
According to a more recent version of the argument, known as intelligent design, biological organisms display a kind of “irreducible complexity” that could not have come about through the gradual adaptation of their parts through natural selection; therefore, the argument concludes, such organisms must have been created in their present form by an intelligent designer.
