In order to figure out anything, we need reason. Where did reason come from though? How can we prove the existence of reason?
It seems we cannot prove reason with reason, which is circular reasoning, and therefore self-defeating.

My christian friend has argued that since reason cannot be explained by natural means, therefore there must be a supernatural force that allows it to function.

I argued that reason can simply just be, but I would like to know of any other things that I might be able to say.