Denialists will be the death of me. It doesn’t matter how much proof you show them, it’s either never enough, or the source is so suspect (to them) that it negates the value of the proof. Motivated Reasoning taken to the point of madness. And since Denialism runs hand-in-hand with conspiracy paranoia, one is better off spending one’s oxygen trying to convert a Jehovah’s Witness to Voodoo than convincing a denialist that Obama was born in the USA!
So what constitutes proof? I think, our former Prime Minister Jean Chretien said it best:
A proof is a proof. What kind of a proof? It’s a proof. A proof is a proof. And when you have a good proof, it’s because it’s proven.