St.Thomas Aquinas (1225-1274) was born into a noble family near the small town of Aquino which lies between Naples and Rome. He became a Dominican friar in 1244 and was a heavyweight scholar in both senses of the word. Weighing in at around twenty stone it is rumoured that this doctor of the church worked at a desk specially designed to fit around his corpulence. Despite a peripatetic life of preaching and teaching, Aquinas penned over two million words of in-depth theology, his best known works being the Summa contra Gentiles and the Summa theologiae. A summa (summary) was a comprehensive exposition of doctrine.
In these works faith and reason are harmonised into a grand theologico-philosophical system which inspired the medieval philosophical tradition known as Thomism and which has been favoured by the Roman Catholic church ever since. There are many areas of interest to philosophers in Aquinas’ writings, such as Aquinas’ theory of knowledge, his analysis of causality, his writings on God (the ‘five ways’ and the doctrine of analogy) and his teleological theory of ethics. Each of these is mentioned below but there are other areas worth exploring, for example, the saint’s comments on sex and gender.
Aquinas made an important contribution to epistemology, recognising the central part played by sense perception in human cognition. It is through the senses that we first become acquainted with existent, material things. St. Thomas held that the relation of dependence of objects on something which transcends them is disclosed to the observer through the contemplation of material things. Just as our knowledge depends not on innate ideas but perceiving the material world, the same material world is dependent on a productive agent for its existence. Aquinas thought the proposition ‘everything which begins to exist through the agency of an already existent, extrinsic thing’ to be a fact beyond doubt.
In the Summa theologiae Aquinas records his famous five ways which seek to prove the existence of God from the facts of change, causation, contingency, variation and purpose. These cosmological and teleological arguments can be neatly expressed in syllogistic form as below:
1. The world is in motion (motus).
2. All changes in the world are due to some prior cause.
3. There must be a prior cause for this entire sequence of changes, i.e. God.
1. The world is a sequence of events.
2. Every event in the world has a cause.
3. There must be a cause for the entire sequence of events, i.e. God.
1. The world might not have been.
2. Everything that exists in the world depends on some other thing for its existence.
3. The world itself must depend upon some other thing for its existence, i.e. God.
1. There are degrees of perfection in the world.
2. Things are more perfect the closer they approach the maximum.
3. There is a maximum perfection, i.e. God.
1. Each body has a natural tendency towards its goal.
2. All order requires a designer.
3. This end-directedness of natural bodies must have a designing force behind it. Therefore each natural body has a designer i.e. God.
Aquinas devotes a further part of his philosophical writing to the problem of religious language. He accepts that God-talk may be literal or metaphorical but believes that in its literalness it is never univocal or equivocal but analogical. That is to say a phrase such as ‘God is omnipotent, omniscient and compassionate’ represents a relation between what we mean by these terms and the divine nature. God’s nature corresponds and is in ratio to the significance behind these terms, yet still literal in that it reveals to us something about God.
Unlike some of his contemporaries, Aquinas was sympathetic towards and influenced by Aristotle to whom he customarily refers as ‘the philosopher’. In a similar vein to Aristotle, Aquinas formulates a teleological theory of ethics known as natural law. Aquinas assumes that God created the world, that the world reveals his purpose in creating it and that the fulfillment of that purpose is the supreme good to be sought: ‘[Natural law] is the participation of the human person in the divine law of God.’ Elsewhere he declares that natural law is “nothing other than the light of understanding infused in us by God whereby we see what is to be done and what is not to be done.’ This exercising of rational conscience has been at the forefront of Roman Catholic teaching for centuries, though it is not the sum total of it.
Aquinas’ theory of ethics, his writings on God and other metaphysical issues provide a unique contribution to philosophical thought and led Anthony Kenny to call him ‘one of the dozen greatest philosophers of the western world’.