Knowledge Theory of St. Thomas Aquinas
The Theory of Knowledge of St. Thomas Aquinas
1. Realism and Idealism
Philosophical realism, also called objectivism and sometimes materialism, posits that the subjective (psychological, logical, theoretical, etc.) is subordinate to objective reality, which exists externally to the subject. Idealism, conversely, suggests that reality is a configuration of the subject, who becomes the “formarum dator” of experience.
Realism prioritizes the object over the subject, while idealism reverses this order. More precisely, combining subject/object with form/matter:
- Realism: Object-Form, Subject-Matter. The subject is formless matter, receiving sense impressions (phantasmata) to become formed. This resembles the “tabula rasa” metaphor—a wax tablet on which impressions are written. The human soul is a “capability” updated through sensory experience, “in medias res.”
- Idealism: Subject-Form, Object-Matter. This reversed orientation, present in Socratic and Augustinian metaphysics and developed further in modern philosophy from Descartes onward, posits that objective reality is a set of disordered perceptions subject to the perceiver’s structures. Reality is a psychological or ideal configuration. The subject provides the form, while the object is received.
Marx explained this opposition with a chiasmus: “It is not consciousness that determines reality but reality determines consciousness.” However, philosophically, this opposition isn’t mutually exclusive.
From a materialist perspective, true philosophy must be materialistic. If idealism is a true philosophy (though not necessarily a true philosophy), it must be a concealed or reductionist materialism. Idealism would similarly view materialism.
We prefer to call idealist philosophies “formalism.” However, since there are no “separate ways” for a materialist, these forms are materials acting as formal determinants. Following special cosmology, matter (Mi) has three genera: M1, M2, M3.
When one genus is the formal determinant of the other two, we have three types of unigeneric formalisms:
- Primary Formalism: Reduces Mi to M1 (corresponds to corporatism).
- Secondary Formalism: Reduces Mi to M2 (corresponds to psychologism or psychological idealism).
- Tertiary Formalism: Reduces Mi to M3 (corresponds to transcendental idealism).
2. Understanding the Doctrine of the Agent Intellect
Originating with Aristotle (though treated casually), the doctrine of the agent intellect was formulated by Averroes and St. Thomas Aquinas. Realism’s principle is “nihil est in intellectu quod non prius fuerit in sensu” (“nothing is in the intellect that was not first in the senses”). The problem is how sensed particulars become universal concepts. The agent intellect explains universals under the principle of Creation.
Three types of intellect:
- The Divine Intellect: Knows everything in act (God is pure act) and eternally, possessing the formal principles of all created things (universalia ante rem). God created formless matter (M) and applied forms to it.
- The Angelic Intellect: Doesn’t know perfect universalia ante rem, but accesses forms separate from matter (universalia in re) present in species, being pure spirits or separate forms.
- The Human Intellect: Accesses forms through particular substances. While hylomorphic compounds contain universals, these aren’t directly accessible. The agent intellect extracts the universal post rem (Fray Zeferino) or separates form from matter (Balmes). Human knowledge, based on particulars, reaches universals present in the divine mind.