Thomas Aquinas’s Quinque viae, its original Latin title meaning “five ways,” is a segment from Summa Theologica that argues how the existence of God can be proven.
- In his argument from motion, Aquinas asserts that one can prove God’s existence via the idea that nothing moves without first being set into motion by the “first mover,” or a higher power. In his argument from efficient causes, he explains that everything is an effect stemming from a cause—and if one goes back far enough, one discovers the original cause is God. In his Reductio argument, he suggests that it is impossible for everything to rely on time for its existence and that there must be something that exists outside the confines of time. In his gradation argument, Aquinas implies that all morality and quality must descend from an apex perfection, or God. The fifth way is design, in which Aquinas states that nature lacks intelligence and therefore must be directed by someone in order for amazing things to happen or be created.
- Logically speaking, Aquinas’s arguments suffer from a couple problems. Some of his conditions that he takes as truths, from which he deduces the existence of God, are not wholly accurate. For example, he suggests that nature is not comprised of intelligent beings or forces. Based on what we know now, Aquinas’s assumption about nature is flawed, and therefore, using it in his argument about design is faulty logic. Another place where he falters is in his assumption about motion.
- This part of your question is the most difficult to answer, because it depends on your perspective. “Real problems” implies that Aquinas’s arguments are invalidated whole-cloth, I am assuming. From a purely logical standpoint, I don’t think Aquinas’s problems are that serious. Of course, if an atheist were to evaluate whether Aquinas has real problems in his arguments, they might interpret things differently.