Among the three arguments to prove God's existence, I find Aquinas's cosmological argument well-grounded in empirical evidence, and that the focus on simple facts proves acceptable in both historical and scientific dimensions.
Aquinas starts by stating the preliminary matter that God's existence is not self-evident, and therefore we need to examine God's effects, which we are able to observe, to prove God's existence, although we are not able to understand God's nature perfectly. Aquinas provides five ways demonstrate the existence of a transcendent being through empirical evidence. The argument from motion, the argument from the nature of efficient causes, the argument from possibility and necessity and the argument ex gradibus each uses simple and observable facts to prove the existence of God as a prime mover, an ultimate cause, a necessary being and an ultimate degree; the argument from design employs the teleological approach and proves God's existence as a designer by exploring the more complicated nature of things.
Aquinas's discussion of the preliminary matter is essential to understanding his five proofs. His argument's dependence on empirical evidence contrasts with the a priori ontological argument. Rowe, in his critics to the ontological argument, argues that "from the logical analysis of a certain idea or concept we can never determine that there exists in reality anything answering to that idea or concept" (P.108). Aquinas, too, acknowledges the deficiency of an a priori argument. While Anselm, in his Proslogion, argues that "God cannot be thought not to exist" (P.71), Aquinas points out that "the opposite of the proposition God is can be mentally admitted: ....Therefore, that God exists is not self-evident." (P.135) Unable to prove God's existence through the mere idea or concept of God, we base our understanding of God on concrete facts from everyday life, thus avoiding the logic puzzle that scholars like Gaunilo and Kant tend to face when discussing the ontological argument. As a result, the cosmological argument is more straightforward to understand.
Aquinas supports his argument with basic phenomena in the world without bias in selection, in contrary to the teleological argument which only considers the complex facts. We have seen from the film "Judgement Day: Intelligent Design on Trial" that with the advancement of science and technology, the notion of creationism or intelligent design faces tremendous challenges. As scientists discover more evidence on the origin of species, we find less things that remain inexplicable; the unlimited creativity of mankind in the industrial and scientific revolutions throughout history also seems to decrease our awe for the wonders of nature because we have become intelligent designers ourselves. Aquinas's proofs emphasize simple facts like motion, causality, existence of things and degrees of evaluation, and he...