Aquinas means to show "how God's public revelation can be lodged in the reasonable discourse of men together" (44). The Summa is not a grand act of faith (like the Confessions) but rather an even-tempered demonstration of how to talk about Christian things in Aristotelian terms.
Question 1: on what sort of teaching Christian theology is and what it covers
1: While agreeing with Ecclesiasticus that "reason should not pry into things too high for human knowledge," there is a domain "above the understanding of men" needing to be studied because it has been revealed by God.
2: Aquinas distinguishes between two kinds of science: 1) sciences revealed by the innate light of intelligence (geometry), 2) sciences dependent on higher sciences (like optics, dependent on geometry). Theology is a science of this second kind, as it takes on faith principles revealed by God.
3: Despite treating objects of different classes (Creator, Angels, Creatures), theology is a single science because it looks at a plurality of phenomena through a single, divinely-revealed lens. Aquinas also draws on the fact that our senses are plural but our experience is unified as another example of how a plurality can be a unity.
4: Theology is more a contemplative science than a practical one, because it is more concerned with "the divine things that are" than "with what men do" (the domain of ethics, which is a practical science concerned with doings).
5: Theology ranks above all other sciences both theoretical and practical. It is highest theoretically because as opposed to human reason, the light of divine knowledge cannot falter. It is highest practically because it guides men to eternal happiness. If theology borrows from philosophy, it is not out of need but simply for the "greater clarification of the things it conveys."
6: Theology is the unconditionally highest of human wisdoms because "that person is called wise about any matter who there maturely considers the highest cause." It is unconditionally so because holy teaching takes its principles not from human science but from divine science, which is of a different order and the condition for the possibility of human science.
7: God is the subject of the science of theology because he is what is discussed, even though we cannot fully know him. Some think the subject-matter otherwise (symbols, works of redemption, etc.), but these are only important in their relationship to God.
8: Theology is probative once you have faith; that is, when you believe, theology is reasonable. For those who do not have faith, a preliminary set of arguments can be deployed that Aquinas thinks too are rational, but only once that person has been converted by those arguments do strictly theological arguments become rationally credible. Once again, Aquinas mentions the limited usefulness of philosophy for perceiving the truth, if incompletely, by natural reasoning.
9: It is acceptable to use metaphoric language in theology because, in the words of Dionysius, "the divine rays cannot enlighten us except wrapped up in many sacred veils." But Aquinas makes it clear that while poetry uses metaphor for delight, holy scripture uses it only for its usefulness.
10: One passage of scripture can have several senses because when God conveys what he understands all at once, it appears of necessity to us in parts and obscurely, because we do not have his understanding. Thus, all meanings are based on the literal sense in which God meant them.
Question 2: whether there is a God
1: Aquinas combats Anselm by saying that though we might know it to be true that God exists, we do not fully comprehend what this means; we can thus know that God exists without experiencing that fact as self-evident.
2: That God exists can be made evident in arguing from effects to causes, though because God and his effects are incommensurable, knowledge of God in this manner cannot be comprehensive.
3: The five ways of proving God's existence:
a. CHANGE - Anything being changed is being changed by something else, and this chain of changes assumes a first cause of change not itself being changed by anything.
b. CAUSE - Everything has a cause that is not self-produced; going back through the chain of effects we are led to a first cause.
c. NECESSITY - Some things do not exist of necessity; but if everything need not be, then once upon a time there was nothing. We are forced into supposing something which must be.
d. GRADATION - The relative scale of goodness and badness assume a superlative goodness.
e. ORDER - Things that tend toward a goal do not do so by accident (like Paley's watch argument....watch indicates watchmaker).
Question 3: God's simpleness
Bodies can be changed, possess potentiality, are not totally excellent, are composed of matter and form, cannot be identified with their essence, belong to a genus, possess accidents, have parts, and enter into composition with other things. God ain't.
We are not covering Questions 4-11, but they continue asking about God's attributes, which include perfection (4), goodness (5&6), limitlessness (7), existence in things (8), unchangeableness (9), eternity (10) and oneness (11).
Question 12: how God is known by his creatures
Created minds can see the essence of God only with the aid of his grace, not by means of any likeness or image and not in the way we see normal visible things, that is, in parts, but rather all at once. Of those who are blessed enough for God to shine a light, some are greater than others. Even those who are blessed do not fully comprehend him, nor are they thereby possessed of the gift of seeing all things.
For the rest of us "mere men," though we cannot see God's essence, we can attain knowledge of him through our natural reason. When we use our reason to trace the objects of our senses back to their source rather than investigate the sensible things themselves, we can gain knowledge of God. But there is always a more perfect knowledge of God through grace. Prefiguring Kant, Aquinas distinguishes between sensing, understanding and reason; but while Kant stops at reason, Aquinas adds on top of these the grace of the divine intellect, the only lens through which to see God's essence.
Question 13: theological language
Aquinas is dealing in this section with the supposed "beyond language-ness" of God. A helpful footnote on page 69 sums up his view: "'God is good' means according to St. Thomas, that what we call goodness in creatures pre-exists in him in a higher way. Our understanding of how to use 'God is good' is a function of our understanding of goodness in creatures, but the goodness of God is not therefore a function of the goodness of creatures. In this sense 'good' as applied to God does not have contained within its meaning the goodness of the creature."
One of the consequences of this view is that we needn't abuse language to talk of God. "Good" and "wise" are not synonymous. They are used literally, even if inappropriately given that they are uttered by finite creatures. We can even speak of God in terms of temporal succession precisely because we know him through his perfections, which are temporal. But we should still understand these descriptors equivocally; "good" as it applies to creatures should be kept apart from "good" as it applies to God.
Aquinas rejects the idea that "good" and "wise" are solely negative (Maimonides) or relational (Alan of Lille) terms; these words do say what God is but imperfectly. It is thus possible to make affirmative statements about God by representing his unity by bringing together subject and predicate.
Aquinas offers his own choice for the most appropriate name for God, He who is, because a) it signifies existence itself, b) it is universal, c) it is present and not past or future.
SOME KEY IDEAS:
1. COMPLEMENTARITY OF THE NATURAL AND THE SUPERNATURAL: Aquinas does not see faith and reason, the supernatural and the natural, Augustine and Aristotle maybe, as opposed but as mutually dependent. "Science remains science when suffused by revelation, just as sensation and emotion are none the worse but better off when caught up by intelligence and friendship" (101).
2. EXISTENCE AND ESSENCE: Although Aquinas is one of the first modern philosophers in that he starts from sense experience, in that he privileges existence over essence, objectivity over subjectivity, he is still a Christian philosopher: "Knowledge of God is the ultimate end of every human cognition and operation" (Copleston, p. 310). And furthermore, there is a more intimate knowledge of God to be had than one can attain in this life.
3. TRUE BUT IMPERFECT: Aquinas believed that it was possible for a "philosopher to work out a true metaphysical system without recourse to revelation," though that system would be necessarily incomplete. Resisting St. Bonaventure, who believed that one can only attain the truth in the light of faith, Aquinas makes room for Aristotle.