Saint Thomas Aquinas: Key Philosophical and Theological Concepts
Saint Thomas Aquinas
Relationship Between Faith and Reason
Reason and faith are two distinct fields of knowledge with an area of intersection, and they converge on a single truth. Reason can demonstrate the preambles of faith, while faith clarifies, argues, and refutes criticisms. Sensory experiences do not contradict faith. Faith addresses issues that humans cannot reason or prove. However, there is a convergence field that includes demonstrable truths of faith, rationally.
Theory of Metaphysics / Theory of Reality / Ontology
Substance is composed of essence and existence. Essence is matter and form and is thought of as divine existence.
Therefore, essence is power. Everything exists because God wants the essence (power) to be transformed into existence (the act). God is the prime mover. God is pure existence (pure act), and His essence is given because God’s essence and existence are necessary, while other beings are contingent. Material substances participate in and tend toward the love of God, but God does not participate in them.
Theory of Knowledge
There are two types of knowledge:
- Sensory Knowledge: Sensory information perceived as characteristics of substances through the senses, aided by imagination and memory.
- Rational Knowledge: Knowledge that, through sensory input and reason, abstracts the form of substances and develops concepts of understanding.
Anthropological Theory
The human being is a being created by God and endowed with rationality, will, and freedom, which has a substantial union of body and soul. God creates each individual soul. The soul is immortal and survives the body. The ultimate goal of humans is to know God and have a loving union with Him. Rationality allows us to distinguish between good and evil. Evil is not following the path of God. Humans are responsible for their choices and will be judged by God at the end of their lives. God created the universe out of love, giving it a permanent order called the eternal law.
Theory of Ethics and Politics
Nature is the set of principles that remain and characterize beings, especially humans, which we call natural law. These principles or provisions may be biological, moral, etc. Natural law has primary principles that are universal, obvious, and necessary, and secondary principles, which are not as primary but should be. The primary principles are that people tend to preserve their existence as substances, that humans tend to reproduce as animals, and that human beings tend to seek truth and live in society, as rational beings.
Positive law is the written law in force in society and must be in harmony with natural law. If something contradicts natural law, it would be against the eternal law of God and against human nature and would not have to be obeyed but changed. Natural law states that human beings have rights by virtue of being persons.
God
The existence of God can be rationally demonstrated, but His essence is dogmatic (one must have faith to believe in it).
The proofs of God are of two types:
- A priori: Begins with the concept of an idea, which argues for the purpose of demonstrating the existence of God.
- A posteriori: A test of an observable fact of nature that concludes, after an argument, the existence of God. This type of demonstration is what Thomas Aquinas made.
Thomas divided his demonstration into five ways with four premises.
The Five Ways
- First Way or Movement Theory: (1) All material beings move, (2) everything that moves must be moved by another being, (3) this chain cannot be carried to infinity, (4) there is a stationary engine, and that is God (because He has no power).
- Second Way or Theory of Quality and the Efficient Cause: (1) All effects are produced by causes, (2) there is a causal chain (rational order of the universe/eternal law), (3) as the string cannot be led to infinity, (4) there is an efficient cause of the universe, and that is God (because He is self-funded and operator).
- Third Way or Contingent Being Theory: (1) All materials are contingent beings, (2) contingent beings depend on other contingent beings, (3) this chain cannot be carried to infinity, (4) there must be a necessary being, and that is God (because He is the creator and necessary).
- Fourth Way or Theory of Degrees of Perfection: (1) In all material beings, there are degrees of perfection, (2) all tend to perfection, (3) as the chain cannot be carried to infinity, (4) there is a perfect being, and that is God (because He is the highest degree of perfection).
- Fifth Way or Theory of Purpose: (1) All people pursue material goals, (2) irrational beings are rationally designed (by the eternal law), (3) this chain cannot be carried to infinity, (4) there is a final cause, and that is God (because He is perfect and, therefore, the ultimate goal of beings).