✝ Catholic Treasury Network

Free course · 10 lessons · about 8.5 hours

Foundations of Thomistic Philosophy

A clear, step-by-step introduction to the philosophy of St Thomas Aquinas, written for secondary students. Learn how to think clearly, what is real, who you are, and how to live well, with readings from this site and from Aquinas and Aristotle themselves.

Start Lesson 1

How each lesson works

  1. Read first. A short reading from this site to prepare.
  2. Learn. The lesson itself, with examples and tables.
  3. Read the source. A short passage from Aquinas or Aristotle.
  4. Check. A five-question quiz with explanations.
  5. Think. Discussion questions and a short homework task.

Your quiz scores are saved in this browser only, so you can pick up where you left off. No sign-up is needed.

Tools for thinking

  1. Why Philosophy? What philosophy is, why truth exists and can be known, and how faith and reason work together. 50 min
  2. Thinking Clearly The three acts of the mind, how a syllogism works, the difference between valid and sound arguments, and five common fallacies. 50 min
  3. How We Know How knowledge moves from the senses to the intellect, what truth is, and why scepticism and relativism undermine themselves. 50 min

Reality, God and the person

  1. What Is Real How act and potency explain change, the difference between substance and accident, and the four causes that explain why things are as they are. 50 min
  2. Does God Exist? Aquinas's arguments from motion, causation and contingency, why an endless chain of dependent causes explains nothing, and what to say to "Who made God?" 50 min
  3. What Is a Human Being? The soul as the form of the body, intellect and will as spiritual powers, and why the human soul survives death. 50 min

How to live

  1. Happiness and the Meaning of Life Why every choice aims at some good, why wealth, honour, pleasure and power cannot satisfy us, and where perfect happiness is found. 50 min
  2. Virtue and Character How virtues are good habits built by repeated choices, the four cardinal virtues, and virtue as a mean between two vices. 50 min
  3. Natural Law and Conscience The first principle of the natural law, the basic human goods it protects, how to judge an act by its object, intention and circumstances, and how conscience is formed. 50 min
  4. Living with Others Why human beings are social by nature, what the common good is, the family and the state, rights and duties, and a final project that brings the whole course together. 60 min

For teachers and parents

The course can be taken alone or used in class. Each lesson fits a 50-minute period, and the discussion questions work well in small groups. Lessons 3, 6 and 9 end with a one-page reflection, and Lesson 10 closes with a final project that draws the whole course together.

You are welcome to link to these lessons from your school's learning platform. Get in touch if you would like to use the course with a class.