Aquinas, unlike Avicenna, Averroes, etc., thinks that God acted freely in creating the universe: He could have chosen not to create at all.
But given that God did choose to create, how much freedom does Aquinas think God had in what kind of world He created? Specifically, what kinds of beings could God populate His creation with? There are two possibilities here:
- Given that God chooses to create, there is only one possible set of beings with which to populate the world, and God has no choice over whether or not to create those kinds of beings.
- Given that God chooses to create, there are a number of possible sets of beings with which to populate the world, and God can choose which set He actually creates.
In Summa Contra Gentiles 3.97.10-11 Aquinas says that the distinction in the different kinds of things follows from a distinction in numerical grades in perfection. As Aristotle and Boethius say, species are like numbers. Therefore, you can arrange all the species on a chain of being going from the highest angel down to the lowest kind of material thing (some kind of dirt, I guess), where each member of the chain is one “perfection point” higher than the one below it. That makes it sound as if the kinds of things that make up the universe is logically pre-determined: there’s exactly one species that fits each slot on the chain.
This seems to be corroborated in SCG 2.91.6, where he says that “all possible natures are found in the order of things: otherwise the universe would be imperfect.” If by “possible” Aquinas means “logically possible,” then Aquinas is saying that God, because He is perfect, can only create a world with exactly the kinds of beings that the world does, in fact, has. So God couldn’t have created Middle Earth, or a universe with unicorns or dragons. This is a severe limitation on divine freedom- and one that runs against my Christian theological intuitions (although I can’t think of a place in Scripture that explicitly goes against this view).
On the other hand, if by “possible” Aquinas means “possible within the world God chose to create” that leaves open the possibility that God can pre-determine, by free choice, which kinds of things are, in fact, possible in the world He chooses to create. This view seems to be corroborated by SCG 3.97.13, where Aquinas says that the precise “measure of perfection” by which God creates is up to His will. That sounds like, although all theoretical species in God’s mind fill out all possible grades of perfection, God can pick and choose precisely which ones he uses.
But that, in turn, could mean one of two things:
1. In a theoretical order of possible species ABCDEFG, God can pick any set of them (ABC, ABDG, CEG, etc.). This is a very broad view of divine creative freedom.
2. In a theoretical order of possible species ABCDEFG, God can pick any adjacent set of them (ABC, ABCD, CDEF, etc.). This is a much more restricted view of divine creative freedom.
At the end of the day, I’m not sure what Aquinas thinks about this question. But he may think God is much more restricted in His act of creation than is usually supposed. I may have to write about this more in the future.