Sweetheart (and I mean that), you can't prove something the existence of which is metarational. You have to come to realize that all reason is based on concepts, and all concepts are based on words, and all words are ultimately defined circularly. There is no such thing as reason, existing in a vacuum.

Reason is like a rowboat floating on a sea of nonreason. It is supported by nonreason, and without nonreason it would sink.

This is not a popular notion, because to most people reason stands for CONTROL; and people want to be in CONTROL But control is an illusion.

EDIT: You suggest a double standard, in that I presume one thing and you presume another. But I am not erecting my presumption as a counter to yours; I am simply showing the weakness in your presumption that the alternative to your position cannot exist. I have not made that statement; you have. You have posited that, if the contrary cannot be demonstrated, it has no right to exist; I have not said that. You are free to think as you wish, and I have not tried to prove you wrong (did you miss that?). I have only tried to show you that your assumption -- that, if the contrary cannot be proven right, your position must be accepted as true -- is logically flawed.