Philosophical Arguments for the Existence of God: From Augustine to Aquinas

Posted on Nov 4, 2024 in Philosophy and ethics

St. Augustine and Christian Philosophy

Neoplatonism’s Influence on Augustine

Influenced by both Christian thought and Cicero’s philosophy, St. Augustine sought to reconcile faith and reason. He initially embraced Manichaeism, a pagan philosophy positing the existence of good and evil principles. However, through Neoplatonism, he found a path to Christianity, rejecting Manichaeism’s dualistic worldview.

Neoplatonism’s key tenets that resonated with Augustine include:

  1. The soul’s superiority over the body: The body serves the soul, and upon death, the soul returns to heaven, without reincarnation.
  2. The theory of light: A connection exists between the lower body, the upper body, and the soul (head).
  3. Free will as the origin of evil: Humans, possessing intelligence, can choose good or evil. Evil arises from our imperfect choices.

Augustine’s Synthesis

Augustine aimed to construct a Christian philosophy based on these Neoplatonic concepts, integrating them with core Christian beliefs.

St. Anselm’s Ontological Argument

St. Anselm presented two types of arguments for God’s existence:

A Priori Argument

This argument, independent of experience, relies on the concept of God. Anselm’s ontological argument posits that God, being the most perfect being, must exist both in mind and reality. Otherwise, a more perfect being (existing in both mind and reality) would be conceivable, leading to a contradiction.

St. Thomas Aquinas’ Five Ways

St. Thomas Aquinas offered five a posteriori arguments, based on empirical observation, to demonstrate God’s existence:

1. Motion

Everything in motion is moved by something else. This chain of movers requires a First Mover, itself unmoved, which Aquinas identifies as God.

2. Efficient Cause

Everything that exists has a cause. This chain of causes necessitates an Uncaused Cause, an eternal being without beginning or end, which Aquinas identifies as God.

3. Contingency

Contingent beings are those that could not exist. The existence of contingent beings implies a necessary being, which cannot not exist, which Aquinas identifies as God.

4. Degrees of Perfection

We observe varying degrees of perfection in the world. This hierarchy of perfection implies a most perfect being, the ultimate standard of perfection, which Aquinas identifies as God.

5. Order of the World

Even irrational beings act towards a purpose. This implies an intelligent designer who directs all things towards their ends, which Aquinas identifies as God.

The Modern Age and the Scientific Revolution (17th-18th Centuries)

The Renaissance and the Enlightenment marked a shift in thought. The scientific revolution challenged Aristotelian physics, leading to the acceptance of the heliocentric model and the mathematization of the universe. This era embraced the hypothetical-deductive method, combining reason and experience. These changes contributed to the secularization of thought.

Steps of the New Scientific Method:

  1. Observation of a phenomenon
  2. Hypothesis formation
  3. Theory development
  4. Verification and establishment of scientific law