History of Western Philosophy - Bertrand Russell [258]
Aquinas, unlike his predecessors, had a really competent knowledge of Aristotle. His friend William of Moerbeke provided him with translations from the Greek, and he himself wrote commentaries. Until his time, men's notions of Aristotle had been obscured by Neoplatonic accretions. He, however, followed the genuine Aristotle, and disliked Platonism, even as it appears in St Augustine. He succeeded in persuading the Church that Aristotle's system was to be preferred to Plato's as the basis of Christian philosophy, and that Mohammedans and Christian Averroists had misinterpreted Aristotle. For my part, I should say that the De Anima leads much more naturally to the view of Averroes than to that of Aquinas; however, the Church, since St Thomas, has thought otherwise. I should say, further, that Aristotle's views on most questions of logic and philosophy were not final, and have since been proved to be largely erroneous; this opinion, also, is not allowed to be professed by any Catholic philosopher or teacher of philosophy.
St Thomas's most important work, the Summa contra Gentiles, was written during the years 1259–64. It is concerned to establish the truth of the Christian religion by arguments addressed to a reader supposed to be not already a Christian; one gathers that the imaginary reader is usually thought of as a man versed in the philosophy of the Arabs. He wrote another book, Summa Theologiae, of almost equal importance, but of somewhat less interest to us because less designed to use arguments not assuming in advance the truth of Christianity.
What follows is an abstract of the Summa contra Gentiles.
Let us first consider what is meant by 'wisdom'. A man may be wise in some particular pursuit, such as making houses; this implies that he knows the means to some particular end. But all particular ends are subordinate to the end of the universe, and wisdom per se is concerned with the end of the universe. Now the end of the universe is the good of the intellect, i.e. truth. The pursuit of wisdom in this sense is the most perfect, sublime, profitable, and delightful of pursuits. All this is proved by appeal to the authority of the 'The Philosopher', i.e. Aristotle.
My purpose (he says) is to declare the truth which the Catholic Faith professes. But here I must have recourse to natural reason, since the gentiles do not accept the authority of Scripture. Natural reason, however, is deficient in the things of God; it can prove some parts of the faith, but not others. It can prove the existence of God and the immortality of the soul, but not the Trinity, the Incarnation, or the Last Judgment. Whatever is demonstrable is, so far as it goes, in accordance with the Christian faith, and nothing in revelation is contrary to reason. But it is important to separate the parts of the faith which can be proved by reason from those which cannot. Accordingly, of the four books into which the Summa is divided, the first three make no appeal to revelation, except to show that it is in accordance with conclusions reached by reason; only in the fourth book are matters treated which cannot be known apart from revelation.
The first step is to prove the existence of God. Some think this unnecessary, since the existence of God (they say) is self-evident. If we knew God's essence, this would be true, since (as is proved later) in God, essence and existence are one. But we do not know His essence, except very imperfectly. Wise men know more of His essence than do the ignorant, and angels know