My existance is contingant only on my knowing it. The existance of the computer on front of me is contingant only on my knowing it. The existance of God is contingant on my knowing it.
If things that I know exist don't actually, then my knowing is no guide to anything actually existing - not even myself.
You've got it the wrong way round. Your knowing you exist is contingent on you actually existing, and you knowing God is dependent on God existing.
A claim to knowledge about a thing isn't proof of that thing actually being true. If the thing is true, then you can be said to know it; if it isn't true then your claim to knowledge was mistaken.
Do you know you exist? Or, on what is your existance contingant?
Yes. My existence is contingent on many things, but not on my knowledge that I exist (which is actually a consequence of existing).
The true mystery of the world is the visible, not the invisible
™ Version 4.2
