Faith and Reason: Thomas Aquinas’ Theory of Knowledge
Theory of Knowledge
Thomas Aquinas’ model of the relationship between faith and reason grants greater autonomy to philosophy. It is based on two clear principles: natural reason and truths of faith revealed by God. Philosophy can be developed without starting from faith, as natural reason is its foundation, while theology is based on divinely revealed truths.
Unlike Augustine, Aquinas emphasizes the more scientific side of philosophy. He views it as a science that takes its principles from another source. He distinguishes between the existential philosopher and the knowledge itself. Thus, although philosophy does not provide salvation, a Christian philosopher does not directly use faith when doing philosophy.
Aquinas distinguishes between the order of nature, where the human being is considered a natural being with specific characteristics and reason, and the order of grace, where man is elevated to the status of the son of God. In the order of grace, grace elevates nature, repairs original sin, and allows man to achieve his supernatural end. The origin of nature is subordinate to grace, but nature is autonomous because God’s natural creation has its own consistency.
Philosophy is an exercise in understanding the natural order. It is not necessary to assume that understanding is naturally lit by God to reach truths of the natural order.
The intellect, as conceived by Aquinas, is an intellectual light that partakes of God’s intelligence. This capability enables access to God, not only in the order of faith but also in the natural order.
The relationship between natural truths and truths of faith is explained by considering the truth of faith as superior to the truth of reason, from which there can never be a contradiction. Aquinas identifies two types of faith: those above reason, which are inaccessible to human understanding and cannot be proven (mysteries of faith), and those within the reach of reason, truths that philosophy can understand by using reason. The mysteries of faith can be explained as not absurd, but real.
Although some revealed truths are accessible to reason, God’s disclosure of them was appropriate.
Regarding knowledge, Aquinas followed Aristotle and qualified the ideas of Augustine of Hippo. For Aquinas, there is nothing in the understanding that had not been through the senses, although the object of true knowledge is the universal, not just the particular.
For Aquinas, knowledge involves:
- Understanding as Possible (Potential Intellect): This is the intellectual power capable of receiving any form in an intangible way and mounting it as a concept. It is not located in a specific physical body because, if so, it would be limited in its ability to receive different types of forms.
- Understanding or Intellect (Active Intellect): This is the intellectual act that illuminates the images to extract an intelligible form. This understanding is in power to understand, but power does not move itself. Therefore, we need to admit the presence of the agent intellect, the first act in the intellectual order that moves the intellect and can be updated through its operations.
This understanding is personal and can be explained as a light owned by the Word, who enlightens every person. Therefore, it must lie in the natural order, not of grace or the supernatural. Natural reason has autonomy from supernatural faith.
For Aquinas, knowledge is acquired in these steps:
- Understanding of Indivisibles (Apprehension): Understanding, where possible, is like a blank page prior to receiving intelligible forms. These forms are drawn from information captured by the senses, which are recorded in the imagination as particular images.
- Abstraction: This is the step to the universal from the individual, by the active intellect, illuminating the images of imagination. Thus, it deprives the individual object of specific characteristics, leaving only the essential thing.
- Elaboration of the Concept: Based on the universal, understanding develops the concept as possible, while still abstract.
- Composition and Division or Judgment: Actual knowledge occurs when the concept is applied to sensory images. This is done through judgments, consisting of affirming or denying a predicate of a subject and stating a reality in one way or another.