Faith, Reason, and the Existence of God in Thomistic Thought

Posted on Dec 3, 2024 in Philosophy and ethics

Faith and Reason

St. Thomas adopts the Aristotelian theory of knowledge, which originates in sensory experience. Our understanding is of objective material realities. Although the mind is immaterial and aims without limitation, the human mind is linked to sensory experience; therefore, its proper object is sensible reality. This idea has two consequences:

  1. Construction of thought has to go from the bottom up, from sensible realities.
  2. The maximum that can be thought of God must be imperfect and analogical, based on the analogy between the limited realities we know and their infinite cause, which is inaccessible to human reason.

Knowledge about God, humanity, and the universe has limits. Christian faith provides information on the nature of God and humanity’s destiny, so reason can approach it as closely as possible. Therefore, faith and reason are different. Although they have different contents, they share common truths reached through logical and rational discourse, which the Christian faith recognizes. This thesis presents a risk to Christianity because it allows reason to contradict articles of faith (Averroes). However, it has the advantage that reason, strengthened by faith, gains credibility. The existence of common content between faith and reason raises some questions:

  1. The existence of truths common to both: St. Thomas gives two reasons:
    1. Circumstantially, some truths should be accessible through reason for those whose philosophical training is insufficient.
    2. Structurally, it is desirable given the possibility of error that constantly threatens reason.
  2. The distinction between two sources of knowledge: Theology takes the contents of faith, and philosophy of reason. As information sources, both are autonomous and independent but they help each other:
    1. Theology receives its principles from faith, but benefits from:
      1. Its scientific management procedures, allowing it to become an organized system of propositions.
      2. Its dialectical weapons to deal adequately with philosophical claims that contradict articles of faith.
      3. Scientific data or input from philosophy that might elucidate articles of faith.
    2. For St. Thomas, faith also serves reason: the articles of Christian faith contain undoubted statements that must guide reason. Thus, if reason reaches conclusions incompatible with faith, they are wrong and must be corrected. Faith is an extrinsic and negative criterion, as it cannot be used for your conclusions.

Demonstration of the Existence of God: The Five Ways

For St. Thomas, reason’s fundamental mission is to demonstrate God’s existence. Despite his religious environment, he believes that God’s existence is not immediately obvious to the human mind and therefore needs proof. To achieve this, we must start thinking of beings in the world as effects, leading to God as their cause. Demonstrations from causes to effects are called a posteriori.

St. Thomas proposes five arguments or ways leading to God’s existence. These five ways have a similar structure, each developing through four successive steps:

  1. Establishment of a fact of experience (we see that things move).
  2. Application of the principle of causality to the observed fact (what is moved is moved by another).
  3. The claim that an infinite series of causes is impossible (there cannot be infinite beings moving each other).
  4. Affirmation of God’s existence (there is a first unmoved mover, which is God).

The five ways are:

  1. From movement to an unmoved mover (God).
  2. From caused causes to an uncaused cause.
  3. From contingent beings (which may exist or not) to necessary beings.
  4. From degrees of perfection to a perfect being.
  5. From the order in nature to an ordering intelligence.

Thomistic Anthropology and Intellectual Knowledge

The most important features of Thomistic anthropology are:

  1. The immateriality of the intellect and therefore the soul is the object to be of reality.
  2. Man is composed of the union between body and soul based on Aristotle’s hylomorphism theory. Thus, the human mind has its roots in this union, and its object is sensible material realities.
  3. This connection requires that intellectual knowledge begins with sense knowledge and cannot be exercised without understanding the concepts developed from data supplied by sensory perception.

Intellectual Knowledge

Concepts, intellectual representations of things, are:

  1. Universal: applicable to all individuals of the corresponding class.
  2. Abstract: contains universal features, not individual ones.

Unlike concepts, sense perceptions are not universal. Our senses bring us into contact with individual objects. Through understanding, we move from identifying perceptions to universal concepts. This is done through abstraction from data supplied by sense knowledge. This process is explained as follows:

  1. Understanding has a dual capacity or activity:
    1. Agent Intellect: the capacity for abstract, universal understanding.
    2. Possible or Patient Intellect: the ability to know universally. It depends on the agent intellect and can only know universally if the agent intellect can universalize.
  2. Sense perceptions or imagination leave a particular image or representation in memory. The agent intellect acts on this, stripping them of individual elements and enabling the possible intellect to form universal concepts, leading to knowledge.