!f I were asked for a list of the things I dislike about Christianity, the high regard many Christians have for Aquinas TO THIS DAY would be high on the list. What a Bozo! The following are Aquinas' 5 proofs of God, summarized.
l) The Proof from Motion. We observe motion all around us. Whatever is in motion now was at rest until moved by something else, and that by something else, and so on. But if there were an infinite series of movers, all waiting to be moved by something else, then actual motion could never have got started, and there would be no motion now. But there is motion now. So there must be a First Mover which is itself unmoved. This First Mover we call God.
2) The Proof from Efficient Cause. Everything in the world has its efficient cause--its maker--and that maker has its maker, and so on. The coffee table was made by the carpenter, the carpenter by his or her parents, and on and on. But if there were just an infinite series of such makers, the series could never have got started, and therefore be nothing now. But there is a maker for everything there is! So there must have been a First Maker, that was not itself made, and that First Maker we call God.
3) The Proof from Necessary vs. Possible Being. Possible, or contingent, beings are those, such as cars and trees and you and I, whose existence is not necessary. For all such beings there is a time before they come to be when they are not yet, and a time after they cease to be when they are no more. If everything were merely possible, there would have been a time, long ago, when nothing had yet come to be. Nothing comes from nothing, so in that case there would be nothing now! But there is something now-the world and everything in it-so there must be at least one necessary being. This Necessary Being we call God.
4) The Proof from Degrees of Perfection. We all evaluate things and people in terms of their being more or less perfectly true, good, noble and so on. We have certain standards of how things and people should be. But we would have no such standards unless there were some being that is perfect in every way, something that is the truest, noblest, and best. That Most Perfect Being we call God.
5) The Proof from Design. As we look at the world around us, and ourselves, we see ample evidence of design--the bird's wing, designed for the purpose of flight; the human ear, designed for the purpose of hearing; the natural environment, designed to support life; and on and on. If there is design, there must be a designer. That Designer we call God.
I've asked it before on this blog, I'll ask it again: whom was Tommaso d'Aquino (1225 – 7 March 1274) addressing with these celebrated so-called proofs? We can only infer about people's private communications from the written record which has survived, and one person can never know with certainty what any other person is thinking, except through telepathy, whose existence I regard as about as convincingly proven as God's. But to judge from the surviving written record, no one within hundreds of miles of Aquinas, during his lifetime, could express the faintest doubt about God's existence without being gruesomely tortured and burnt alive for it. Those whom Aquinas regarded as his most evil adversaries, Muslims and Jews, believed in a God with just about exactly the same attributes as those Aquinas imagined. Well, it's possible that Aquinas didn't know that, although it boggles the mind. And some scholars contemporary with Aquinas had had the temerity to write some positive things about some Muslim authors such as Averroes, occasioning one of the most angry of Aquinas' depressingly numerous books.
But no, although Aquinas flew into any number of hissies about what he saw as the errors in the descriptions of the attributes of God written by Christians and Muslims, he definitely knew that they all believed in God's existence.
Is it possible that the thing against which Aquinas was mightily struggling with such things as his 5 proofs were the faint murmurs of common sense inside his own brain (which he undoubtedly would describe as the efforts of Satan to drag his eternal soul down into Hell forever)? The thing is, I haven't yet found anything else which it possibly could be. To many Christians, Aquinas' writings represent the pinnacle of human wisdom. To me, they look like very much the opposite: an attempt to oppose clear thought at every turn with every available means, a desperate battle against the free use of yr brain.