"Descartes was the first to come up with the concept of the 'brain in the vat,' being unable to tell reality from a carefully constructed delusion," Zatanna explained. "Finally, he decided that, 'I think, therefore I am,' meaning accepting reality was easier that coming up with a convoluted theory on how everything was an illusion."
"In my universe, at least, Hugh Everett came up with the concept of multiple universes. For example, in your universe, you opened up the package, and the end result is me and you having the surreal conversation about reality. Perhaps there's another reality where the package got lost, or wasn't sent, or where you got it, but the laws of physics were such that it didn't suck any individuals from other universes."
"I think where you might be getting philosophically frustrated is that these retcons, contradictions, would seem to prevent me from existing, or at least me existing as a being from another universe. Now, there's a number of ways to look at this. You could consider comic books like history books. And you know how two historians can disagree hows and whys of a certain event, even if said event happened within their lifetime. Or what if the comic books are representing not one reality, but multiple realities. With that much....for lack of a better word, 'bleed over,' there's bound to be some inconsistencies in the facts as they're presented, particularly if the individuals who are writing these histories from their subconscious don't know they're writing history."
"So, Descartes and Everett would both argue that I'm real, and my world is real, and possibly there are more worlds out there with their own versions of Leos and Zatannas. Or possibly there is only one Zatanna, which would relieve quite a few people," she said with a laugh, "And these retcons, as you call them, are a product of bad reception by whatever method your comic book artists and screen writers are copying down the events of my world and other worlds like them."