This semester's reading list has me thinking about Anselm's Proslogion back to back with Augustine's On Free Choice of the Will. Each book has an argument for God's existence. These arguments are rather different from each other. But at the moment, it's hard for me not to think of the Proslogion argument as a deliberate improvement on Augustine's argument in Book II of On Free Choice.
One reason I think this is because of what each argument tells us about what it would take for some existing thing to be God.
For Augustine, here is what it would take: if x is "superior to" the human faculty of understanding, and superior to it in the specific sense that x is "eternal and unchangeable," then either x is God or there is something else, y, which is superior to x and y is God. In Augustine's own argument, he tries to establish the existence of eternal truths of "number and wisdom." Since these truths are superior to human understanding in the relevant respects, God exists.
One upshot of the argument is that it is enough for something to be God, that it be the best thing that exists.
This seems totally bizarre to me. What if the best thing that exists isn't very good?
My reaction to Augustine's argument tells me something about what I think worship is and what I think makes something worthy of worship.
As a Christian, I've been formed to think of God as something whose claim over us is comprehensive and unconditional: "The LORD our God, the LORD is One. And you shall love the LORD your God with all your heart and with all your soul and with all your strength."
What can demand this kind of giving up of ourselves? Surely not something that is just a bit better than we are.
Anselm's Proslogion is a work of religious genius in part because of the answer it implicitly gives to this question. The book begins with an act of worship and a request to understand that which the author believes. Anselm's famous argument sets out to prove that there exists "that than which nothing greater can be conceived." And he assumes that proving the existence of such a thing is sufficient to prove the existence of God.
Notice the difference here between Anselm and Augustine: for Augustine, to prove God all we need to do is prove that there is something superior to us; for Anselm, to prove God we need to prove that there is something unsurpassably superior to us.
The being addressed in the opening prayer of Proslogion is worthy of that comprehensive and unconditional devotion because it is the best possible, not merely the best.