Essence, Existence, and Knowledge: Aquinas’ Philosophy
Essence and Existence in Aquinas’ Philosophy
+ Presence (Essence):
- It is that which defines an entity.
- It consists of matter and form.
- It is what all people of the same species share, both with respect to form and as the subject.
- It is identified with Aristotelian potentiality because it is something that can develop and change.
+ Existence:
- It is that by which essence exists.
- It is identified with Aristotelian actuality; it is something that actualizes the essence.
For Thomas Aquinas, the core subject lacks the category of quantity and cannot be measured. It is matter in general and prior to individualization. The principle of individuation is matter, but it cannot be categorized.
Without quantity, there is no individuation and existence. Conversely, existence only has sense if it refers to an essence.
- Contingent and Necessary Being
The universe is contingent. This contingency requires a necessary being that created it and has led to existence. The Necessary Being, actualizing essences and bringing about existence, is God.
The distinction between essence and existence demonstrates the contrast between divine necessity and the contingency of creation, and the need for the existence of God to produce the world.
Knowledge According to Saint Thomas
Saint Thomas’s empiricism led him to reject the existence of innate ideas in the mind. For Saint Thomas, the mind is a tabula rasa, and all ideas are formed from what is first captured by the senses.
- Types of Knowledge
Aquinas distinguishes two types of knowledge:
+ Sensitive knowledge: Human beings grasp reality through the senses. Afterward, the mind, through imagination, forms an image of reality.
+ Abstract knowledge: Understanding executes two operations:
a) Abstraction, by which the understanding separates the aspects that are common to a variety of objects.
b) The formation of universal concepts from information obtained by the agent intellect. This process is performed by the passive understanding.
- The Problem of Universals
Like most thinkers, Thomas Aquinas takes a position on the problem of universals. His solution is raised between extreme realism and moderate realism:
- According to extreme realism, there exists an idea or form in the mind of God that is the essence of things.
- According to moderate realism, the formation of concepts occurs through the process of abstraction.
For Saint Thomas, universals are understood in three different ways:
- Ante rem (Before the thing): Universals exist before any reality.
- In re (In the thing): Universals are the forms of individuals, from which they are classified into genera and species.
- Post rem (After the thing): The human mind recognizes the form by abstraction, thanks to the understanding.
Ethics and Natural Law (Saint Thomas)
Aquinas adopts a hedonistic ethics and recognizes that all natural beings tend toward an end. In humans, this end is identified with happiness. He identifies virtue and happiness and distinguishes between two kinds of virtues: theoretical and ethical. These virtues are ways of achieving happiness.
- The theoretical path develops the theoretical virtues. Attaining happiness consists in beatific contemplation.
- The path of habit develops moral virtues.