Thomas d'Aquin
Faith and reason cannot contradict each other.
Thomas d'Aquin (1225 – 1274, Kingdom of Sicily (Italy) · Paris) : thomism (scholasticism) and aristotelianism. Faith and reason come from the same God: they cannot contradict each other. Aquinas takes up Aristotle to build a Christian philosophy. On AskPhilosophy: 8 reconstructed arguments, 5 quotes checked word for word against the original texts, and 4 common beliefs examined; every text carries an authenticity badge (written by the author, posthumous, student notes, reported, apocryphal).
Why he matters
His "five ways" remain the best-known and most debated proofs of God. His natural law theory shaped law, thinking on just war and the teaching of the Catholic Church, which has treated him as its reference teacher since 1879.
His times
Born into a noble family, he joined the Dominicans, an order of mendicant friars, against his family's wishes; they confined him for about a year. A student of Albert the Great, he taught in Paris just as Aristotle's works, recovered in the West through translations from Arabic and then from Greek, were dividing the University. He died at about 49, leaving the Summa theologiae unfinished.
His positions
click a row to see the evidenceGod's existence can be demonstrated by reason, from his effects, and he gives "five ways". But we know what God is not, not what he is.
All our natural knowledge begins from the senses. Reason then rises from sensible things to their causes, as far as knowing that God is, without seeing his essence.
The first principles known by reason are so true that we cannot even think them false. But about God, reason alone reaches the truth only slowly, in few people, and mixed with errors.
The human soul is the form of the body, as in Aristotle, but it has its own being that remains when the body is taken away. Neither a dualist in Descartes's sense nor a materialist. His main texts on the soul (Summa, I, q.75-76) are not yet in our corpus.
The rational creature shares in divine providence by "being provident for itself". Aquinas affirms free choice, but scholars debate how he reconciles it with divine causality. His treatise on free choice (Summa, I, q.83) is not yet in our corpus.
There is a natural law whose first principles are the same for all and known to all. More detailed rules admit exceptions and can be obscured by passions or bad customs.
Harmony: reason cannot contradict faith, because truth does not contradict truth. Reason serves faith without claiming to prove it; some truths (the Trinity) lie beyond it.
Human life has an end: beatitude, which lies in God and surpasses what reason can conceive.
Humans are naturally inclined toward real goods (living, knowing, living in society), but reason can be distorted by passions and bad habits. Grace does not destroy this nature: it completes it.
The individual is part of the community, and every law aims at the common good. But a tyrannical law, contrary to reason, is not truly a law.
A natural law ethics: do good and avoid evil, according to the inclinations reason recognises as good. It is combined with a virtue ethics taken from Aristotle.