At the age of five, Thomas Aquinas was sent to live in the Benedictine monastery at Monte Cassino, so the Church was a very large influence on his life from nearly the beginning. In the middle ages, sons who were not the firstborn male heir of a family were not able to inherit lands and titles from their fathers, so many families would send their younger sons to be raised and educated by the church, ensuring them a future career as a priest or academic. It was to the ire of Aquinas’ family that in 1244, he became a friar of the Dominican order, which was known for its scholastic teaching. Aquinas studied under the scholastic philosopher Albertus Magnus before going to teach in Paris in 1252.[1] By the time he began to teach, Aquinas had been ordained as a priest, and in 1256, he was awarded a doctorate in theology and went to work for the University of Paris as a professor of philosophy. In 1259, Aquinas was summoned to Rome to be an advisor and lecturer to the papal court.[2] He died after falling ill in 1274, but his legacy as a teacher, theologian, and philosopher continued to heavily influence the importance of education in the Catholic church centuries after his death, until the modern age. Thomas Aquinas incorporated Aristotelian ideas into Christian theology despite some backlash against the reintroduction of Aristotle’s writings during Aquinas’ lifetime.

Virtue and Aristotelian Ethics

Aquinas adopted and expanded on Aristotelian ethics as he discussed a greater number of virtues than Aristotle and attributed them to his concepts of good and evil. “Virtues are developed habits of powers disposing agents to good actions.”[3] And were subject to human reason and will. In the exercise of the power of will, virtue was the mean between two immediate extremes, or vices. Aquinas believed that human happiness was twofold; one happiness could be achieved by natural virtues, such as the virtues taught by Aristotle. Examples of these include prudence, justice, courage, and temperance. The other happiness could be achieved by theological virtues, thus incorporating Christian morals into Aristotelian ethics.[4] Examples of theological virtues are faith, hope, and love. Theological virtues and truths of faith do not contradict natural truths acquired by the experience of the senses, they are instead complimentary.[5] Some truths could only be known through spiritual means, others could be known from experience, and some could be known through both. The existence of God, for example, could be known through both spiritual means and the means of reason and experience.[6] While adopting Aristotelian sciences, Aquinas also rejected some aspects of Neoplatonism in Christian thought. He rejected the singular importance of the human soul, and instead, saw human beings as a union of body and soul such as Aristotle did. The resurrection of the bodies of the dead at the end of days seemed to justify the Aristotelian model of the body/soul.

Aquinas sees God as being good, not only in the sense that he is absent of all evil as the perfect being, but that goodness emanates from God to all of creation. God is the cause of the goodness that can be observed in human life.[7] In acts of will humans strive for the highest end, that being good or evil. Given that the nature of good and evil can be learned from experience, human actions are done with good or evil in mind. Good from natural virtues can be achieved through reason alone, but theological virtues can only come from God. This departs from Aristotle’s virtues in that he believed that humans could achieve happiness by living in accordance with reason. Aquinas argues that his extra theological virtues cannot be chosen, but given, from a divine source. When an action deviates from reason or divine moral law, it is an act of evil. For Aquinas, humans are still fallen in that sin resides in human will which will go against reason.[8] Because complete happiness and good can only come by the grace of God, and not solely reason, some humans are predestined to salvation while others are not. 

The Five Ways

Aquinas argued that the existence of God could be proven in five ways. The first way is based on the existence of motion, the second is based on the existence of efficient causality. The reasoning behind the two are similar in that the world is in constant motion where every motion was caused by a previous motion. Every event is caused by a previous one. If we could track every motion and cause back to the beginning of existence there would be an infinite regress because nothing is its own cause. Therefore, something had to start the motion of existence, that something being God. The third way is based on possibility and necessity and states that because there was a time when nothing existed, something must have existed first. The fourth way is based on gradations. There are different levels or hierarchies of all things. Some food tastes better than others, and some trees are taller than others. Because we judge things based on their relevance to another, there must be something that is the highest and most perfect. The fifth way is based on the governance of things. So many things without intelligence like plants, rivers, and other natural phenomenon all adhere to similar tendencies that repeat themselves. “Therefore,” Aquinas says, “there is some intelligent being by whom all natural things are ordered to their end, and we call this being God.”[9] Here in his five ways to prove the existence of God, Aquinas uses Aristotelian methods to support Christian doctrine. Here he has successfully incorporated philosophy into theology.


Island of Freedom – St. Thomas Aquinas

Saint Thomas Aquinas (Stanford Encyclopedia of Philosophy)

Except from SUMMA THEOLOGICA I, Question 2, Article 3 – Whether God exists. Obtained from Island of Freedom – “The Five Ways”

Sources Sited