There's a question about the status of Aquinas' five ways to "prove" God's existence. Are they really proofs after all?
The five ways are:
1) The argument from motion
2) argument from efficient causes
3) argument from possibility and necessity
4) argument from degress of perfection/gradations of being
5) argument from the governance of the world
Concerning these five ways, here's what I once wrote to a colleague:
In Prima Pars, Quest. 2, Articulus 3 of the Summa Thelogiae, Aquinas does write: "Respondeo dicendum quod Deum esse quinque viis probari potest."
But I would agree that reason is limited; a posteriori demonstrations (like the five ways) can only show that God's existence is possible or maybe probable.
For the potential sense of the Latin word, probari, see https://en.wiktionary.org/wiki/probo#Latin
Compare the words of Cicero (Ver. 2.1.10): "his ego iudicibus non probabo C. Verrem contra leges pecuniam cepisse?"