Aquinas’ Aristotelianism: Synthesis of Faith and Reason

Posted on Jan 4, 2025 in Philosophy and ethics

I. The Aristotelianism of Aquinas

The works of Aristotle, lost to the West for centuries, gained prominence in the Middle Ages thanks to the appearance of Arab and Jewish thought. This caused a great stir in European thought, which at the time was dominated by a Platonic interpretation of the world and humanity. With the rediscovery of the full Aristotelian work and the commentaries of Averroes (Ibn Rushd, 1126-Córdoba, Morocco 1198), a philosophically connected movement known as Latin Averroism emerged. It maintained two theses in cosmology and Aristotelian anthropology that were contrary to Christian doctrine:

• The eternity of the world: Aristotle advocated this idea, which clashed with the Christian belief that the world was created by God. For Aristotle, God is merely the unmoved mover of the eternally existing world, but God did not create the world nor have any relationship with it.
• The soul of each human being is not immortal and dies and corrupts, except for the intellect, which is immortal. The intellect, for Aristotle, is present in every human being, but it is a single intellect for all of humanity and is identified with God.

Averroism maintained that truth could have a dual nature: a theological truth and a rational truth. In this way, the current officially opposed the Church, which defended the subordination of reason to faith, believing that truth only exists in Revelation. Aquinas did not sanction the Averroist theses. However, he declared himself a follower of Aristotle, seeing in his theory of the human being and the world a more scientific approach than the Platonic writings. Aquinas proposed to develop a synthesis between Aristotelian doctrine, Platonic philosophy, and the dogmas of the Christian religion, to reconcile three different explanations of the world and human knowledge.

Aristotle’s accepted concepts:

• A theory of movement defined in terms of potency and act.
• The classification of substantial changes (composition and hylomorphism) and accidental changes.
• The theory of the four causes (material, formal, efficient, and final).
• The Aristotelian demonstration of God based on movement.
• The definition of God as pure act and as self-thinking thought.

But to this definition, he added fundamental qualities, such as being the creator of the world.

• The view of humans as a composite of soul and body, in contrast to the Platonic and Augustinian view of identifying the human being with the soul.
• The ethical principle of Aristotle that happiness is achieved through virtuous actions and knowledge.

However, he considered that happiness can only be achieved through the contemplation of God (beatitude: something supernatural that is only reached after death). A major difference is that he considered the will to be the most important faculty of humans, in clear contradiction with Augustine’s emphasis on the will and faith-based ethics. To avoid the most important contradictions with the Aristotelian system, Thomas Aquinas introduced some alien concepts:

• A distinction between essence and existence, taken from Arabic philosophy (Alfarabi and Avicenna) and Jewish philosophy (Maimonides).
• A distinction between the existence of something essentially and the existence of two entities, which allowed Thomas Aquinas to assert the contingency of creation against Aristotle.
• The world exists because God, not only as an unmoved mover, but as the creator of the world.
• The establishment of limited material and immaterial substances, dependent on divine creation.
• The Platonic principle involving the concept of exemplary causality, also assumed by the Platonic Augustinian tradition.

These concepts allowed him to explain the relationship between God and the world.

II. Theory of Knowledge: Abstraction and Moderate Realism

The label “moderate realism” represents Aquinas’ position with respect to two problems treated by the most important thinkers of the Middle Ages: the problem of universals. What is a universal? They are concepts of genus or species that can be predicated of many individuals. That is, they are abstract entities, notions of genus that refer to a plurality of objects (“human being”, “tree”), in contrast to concrete entities (“this house”).

Problem: What kind of existence do they have? What is the relationship between individual beings and concrete and mental concepts?

Exaggerated or extreme realism: Universals exist before things (universalia ante rem). This position has its origin in the Platonic ontology of two worlds, with the world of ideas having a higher degree of existence. Augustine of Hippo placed universals in the divine mind, and therefore they already exist and are more real than concrete things.

Moderate realism: Universals exist as forms in individual things (universalia in re). Aristotle says that the universal is an inherent part of beings, it is their essence, which is grasped by the intellect. This position was adopted by Thomas Aquinas.

Nominalism: Universals are not entities that exist in reality, but only have a logical and mental existence (universalia post rem). Within this position, the conceptualist position stands out, stating that universals are abstractions of individuals. Others, like Ockham, say that they are mere voices, names that are used for things that are similar to each other. That is, only individual objects exist, but since there are similar objects, we use a universal (created by our mind) to name them.

Process of Knowledge of the Universal: Abstraction

Thomas Aquinas distinguishes two activities of the intellect:

• Abstractive capacity: The intellect converts universal representations into sensitive individuals: the agent intellect.
• Capacity to know universally: Stages of the process of understanding:

1. External senses capture the qualities of things.
2. Common sense captures sensitive species (objects without matter).
3. Sensitive species are “stored” in the imagination.
4. The agent intellect acts on these images, stripping them of their individual characteristics and highlighting their essential traits.
5. The intellect can then know the result: an intelligible species.

III. The Problem of Reason and Faith

This is the problem of the relationship between religion and philosophy, that is, the commitment to understanding knowledge based on Revelation and knowledge based on reason. The origins of the problem can be found in the 2nd century, in the first contacts between the two types of knowledge (pagan thinkers and theorists of the new religion). As Christian culture became hegemonic in Europe, the hegemony of faith imposed itself, limiting the free use of reason. Thomas Aquinas carefully distinguishes between faith and reason (see the following table), both in their formal objects and in their research method. However, both types of knowledge are not irreconcilable, since both have the same end, which is truth. The difference is that revelation is a source of truth that never errs, while philosophy can be wrong.