Aquinas’s Philosophy of Knowledge and God’s Existence

Posted on Oct 13, 2024 in Philosophy and ethics

Activity 2B: Aquinas’s Two Types of Knowledge

Sensitive and Intellectual Knowledge

Following Aristotle, Aquinas distinguishes two types of knowledge:

  1. Sensitive Knowledge: Information sent to the “common sense,” forming an image of the object with all its particularities.
  2. Intellectual Knowledge: The understanding operates on the image formed in the common sense, capturing the essential features of the thing through two activities:

Activities of Intellectual Knowledge

  1. The Role of the Intellect: Abstracts the essential features of the thing, stripping it of its particular elements, making the representation universal.
  2. The Function of the Understanding (Passive Intellect): Becomes aware of the abstracted essence, enabling universal knowledge.

The Principle of Individuation

If everyone has the same essence, what makes us unique? According to Aquinas, we all have a common subject matter (essence) and a particular subject that differentiates us.

Essence and Existence

According to Christianity, God is necessary, while other beings are contingent. Aquinas distinguished between essence (what a thing is) and existence (that a thing is). In created beings, essence and existence are distinct, but in God, they are identical.

Aquinas linked essence and existence to Aristotle’s concepts of potency and act: essence is potency, and existence is act. A thing’s existence depends on its essence’s perfection. Only God’s essence is perfect; therefore, God exists.

The Five Ways to Prove God’s Existence

Aquinas offered five ways to demonstrate God’s existence:

  1. Motion: Everything that moves is moved by another. There must be a first mover, unmoved by any other: God.
  2. Efficient Cause: Everything has an efficient cause. There must be a first efficient cause (uncaused cause): God.
  3. Contingency: Some beings exist but could not exist. There must be a necessary being with self-existence: God.
  4. Degrees of Perfection: Things exist in varying degrees of perfection. There must be a maximum degree of perfection: God.
  5. Teleology: Natural things without intelligence are directed to an end. There must be an intelligent being directing them: God.

Activity 2C: Theology, Philosophy, and the Preambles of Faith

Faith, Reason, and Shared Truths

Theology relies on faith, while philosophy relies on reason. Some truths are accessible only through reason, others only through faith, and some through both. According to Aquinas, the immortality of the soul and God’s existence belong to both realms, called Preambula fidei (preambles of faith).

Aristotle’s Influence and Limitations

Aristotle believed the human mind starts with the senses, focusing on sensible reality. Aquinas agreed but argued that understanding is designed around all reality, though human understanding is tied to sensory experience.

This poses a problem: natural knowledge of God is limited and analogical, linked to sensory experience. Christian faith solves this by revealing truths beyond reason’s limits.

The Relationship Between Faith and Reason

The existence of shared content between faith and reason raises two questions:

  1. Why Shared Content? Aquinas argued it’s desirable for some truths accessible to reason to be reinforced by faith, as not all can access them through reason, and reason can err.
  2. Distinct Sources of Knowledge: This distinction is crucial for differentiating philosophy and theology. They differ not in content but in how they access it: theology through faith, philosophy through reason. However, reason aids theology by providing scientific procedures, dialectical tools, and scientific data.

Reason contributes to theology as a science.