Chapter 13. "From the Nature of the Universe" by Thomas Aquinas

Table of Contents
Ideas of Interest from Summa Theologica
The Reading Selection from Summa Theologica
Related Ideas
Topics Worth Investigating

St. Thomas Aquinas, Thoemmes

About the author…

St. Thomas Aquinas (1225-1275), is generally considered to be the most prominent thinker during the Medieval period. Thomas, although primarily a theologian, argues philosophically in many of his works and, unlike St. Anselm, clearly distinguishes between the methods of philosophy and religion. He uses the scientific thought of Aristotle as a method of theological and philosophical understanding. Nevertheless, for Thomas, philosophy is primarily based on the use of reason, whereas religion is primarily based on the use of divine revelation provided by faith. Both kinds of knowledge, according to Thomas, are consistent and compatible. He is convinced metaphysics is the most important aspect of philosophy.

About the work…

Philosophical reasoning, according to Thomas, is sufficient by itself, without faith or revelation, to demonstrate that God exists. Thomas believes God's existence, although not self-evident, can be made evident using reasoning drawn from the nature and structure of the world. The so-called "five ways" are taken from his Summa Theologica.[1] Thomas, as do many philosophers, believes that we can know by reason that God is, but we cannot know what God is. In other words, the nature of God, often defined by the characteristics of perfection, is, according to Thomas, only a linguistic approximation.

Ideas of Interest from Summa Theologica

  1. What is Thomas's objection to the ontological argument?

  2. Why doesn't the observation "whatever is in motion is put in motion by another," logically apply to the First Mover?

  3. Search, locate, and restate a good definition of "efficient cause."

  4. Can you suggest ways to distinguish physical from logical necessity? Provide some examples. Would Thomas distinguish between physical and logical necessity?

  5. What is the difference between the First Cause and the First Mover?

  6. Research the term, "teleology." Explain why Thomas's fifth argument is often called the "teleological" argument.

  7. Restate each of Thomas's five arguments as clearly as possible. What is the major premiss[2] of each argument? What objections can you construct to each of Thomas's arguments?



St. Thomas Aquinas, Summa Theologica second and revised edition, 1920 by the Fathers of the English Dominican Province.


Rhetorically, the major premiss can be thought of as the rule or main generalization upon which the argument is based. I.e., in the argument, "All men are mortal, and Socrates is a man; thus, Socrates is mortal," the major premiss is "All men are mortal."