No, you are not looking at a university student’s blue book . . . But you are seeing a very famous logical proof. This is an image of an early copy of the Medieval philosopher Anselm of Canterbury’s (1033-1109) _Proslogion_, and it used logic to try to prove something unimaginably perfect: the existence of God.
His argument is called an “ontological” proof because it reasons about the state of being of God. It goes something like this: God is greater than anything else we can imagine, and since a real God is better than an imaginary God, if we only think of an imaginary God, then we aren’t thinking about the greatest being imaginable. Therefore, God exists. I skipped a bit, but that’s the general idea. And maybe as we read this over we can already see a weak spot in Anselm’s proof, which is that he assumes _a priori_ that God exists. But philosopher-logicians have taken this argument seriously, even when they disagree with its conclusions.
I think the argument is a really interesting window into the attitude of Medieval Scholastic thought popular in this age. The idea that the universe is reasonable, and managed by a reasonable God, characterises much 11th-century thought.
The interest in proving God’s existence through logic has waxed and waned over time. The second image is a mathematical theorem put forth by the famed 20th-century mathematician Kurt Godel (1906-1978). It too is an ontological theory, and like Anselm’s ideas, has been critiqued for not having demonstrated the axioms used in the formula.
Source(s): MS is BL Harley 203 and Godel’s formula is from Wikipedia. You can read Anselm’s Ontological Proof of God at the Internet Medieval Sourcebook, D.O.I. sourcebooks.fordham.edu/source/anselm.asp
