Faith, Reason, and the Existence of God: Augustine and Aquinas
Faith and reason to believe to understand: One of the major issues that engaged medieval philosophy is the relationship between faith and reason, and Augustine of Hippo is the Christian thinker that further developed this theme. For him, faith and reason have a unique mission to clarify the only truth. His approach can be summarized in his phrase: “Believe in order to understand, understand in order to believe,” which means:
- First, that reason helps man to achieve faith; that is, to believe the truths of faith must be preceded by a work of reason.
- Second, that faith guides reason. That is, it is not philosophical exercise that gives wisdom to man, but faith (believe to understand).
- Third, it helps to clarify the specific content of faith (understood to believe).
The Problem of Evil
The presence of evil in the world is evident to everyone, both physical and moral evil. Herein lies the dramatic and bipolar nature of Augustinian anthropology. Because of original sin, man is hardly free to do good: corrupt nature, original sin, pushes man to do evil. But because of grace, man is hardly free to do evil: the power of grace drives the human being to good. However, neither of the two forces is crucial. The man, free, has a capacity of conditional decision. Among the burden of original sin and the help of grace, he decides whether to follow God, using his freedom, or if he will turn back.
Saint Augustine dedicated efforts, after becoming bishop, to exculpate God from the authorship of evil:
- Evil is a reality, but a lack of reality, a deprivation. Not being a reality, something created, it cannot be attributed to God.
- All created beings are good (because God created them), but not entirely good, because if they were, they would be God. God did not create evil, but good things, which are corruptible.
In conclusion, evil is rooted in human freedom.
Demonstration of God from St. Augustine to St. Thomas
Rationally demonstrating the existence of God is one of the fundamental aspirations of philosophers in the Middle Ages. Saint Augustine wonders how man, who changes, can know truths that do not change. Of course, not through sense knowledge, or by himself, because human beings are like things: contingent, mutable, and transient. He explains this paradox by the theory of Enlightenment: inside a man’s reality is a necessary, immutable, and eternal God (who is the source of all knowledge that has these characteristics). God illuminates the soul and is present in the soul. The man knows these realities by divine illumination. That is the true Augustinian test of God’s existence: the presence in man of universal truths, necessary and immutable (if the man is not one of those things).
Aquinas’ Perspective
For his part, Aquinas believed that proving the existence of God is necessary and possible. Necessary because God’s existence is not obvious to humans, and thus needs to be demonstrated by things known to humans for their effects. And possible because relying on sensible things can prove the existence of God. Always in the same way: first, from sensory experiences. Then there is the impossibility of reasoning to infinity. And finally, it suggests that, logically, there must be a first principle to explain the experience that has broken. In the same scheme, he produces five arguments, the five ways, to demonstrate the existence of God: the path of motion, causation, that of contingency, the degrees of perfection, and teleology.