If I were to debate myself, I would never use mystical experience as an argument for God’s existence because it is non-falsifiable, it is an unfair trump card that avoids logical reasoning. But just as my love for my wife is not the result of a logical demonstration, so, too, my faith in God is not the result of a chain of deduction. Reason can perhaps confirm what we know already by faith, but faith is rarely the result of reason. What’s more, I have this sense that the God of Abraham, Isaac and Jacob is not the Prime Mover of Aristotelian logic… and that to argue for his existence, using the paltry weapons of the human mind, seems almost presumptuous.
The opposition he is drawing here is not between reasoning about God and experiencing him, but between reason as such and experience, where “experience” means immediate knowledge. Briefly, the whole force of this argument comes not from the difference between mediate knowledge of God (theistic proof) and experience of God (mystical or religious experience), but is a general feature of the way in which immediate knowledge is always preferable to mediate knowledge, whether in theology, physics, history, biology, whatever.
It’s very often the case that the things we reason to are more worth knowing than the things we know immediately, but immediate knowledge is a better way of knowing. Ceteris paribus, if we had a choice between a direct knowledge of some reality by an immediate manifestation and a mediate, indirect awareness of it, we’d all choose the first. It would be better, for example, if we could just see some historical event happen rather than have to argue about it through monument inscriptions, testimonies, and probability arguments; it would be better if we could just look up in the sky and see black holes as opposed to inferring them from microwave readings, etc. We only reason because a.) we can’t know something any other way or b.) we can’t unify the things we know any other way c.) we can’t communicate some things we know any other way.
Reasoning is always a substitute for experience, or something that we have to settle for given the impossibility of an immediate knowledge. Since reasoning by definition has no direct access to what it seeks to know and finds itself in a situation where the reality does not manifest itself, reasoning presupposes world that substitutes for the manifestation itself in which it can reason (cf. Chapters 1 and 2 of Sophistical Refutations). This is the world of signs i.e. things which being themselves immediately known make other things known. Instrumental signs thus both manifest something and are a veil in front of it, or perhaps a response to the veil that is, for us, over reality. It is the world of signs, considered as substitutes for things that do not manifest themselves, which opens the possibility of deception, sophistry, lying, and that nagging sense we all have that there is something unreal and even inhuman about reasoning. Just as the continual repetition of a word makes it lose all of its sense in become an irrational clanging sound, so too arguments which go on too long for someone tend to sound unreal to him. Who hasn’t heard someone call an argument “mere wordplay” or a bunch of “empty logic”?
Though the opposition between “logic” and “mystical/religious experience” is a feature of the general opposition between mediate and immediate knowledge, the personhood of God makes this opposition more acute, painful, and troubling. Personal relations give an added force to the desire for immediacy. One could never exchange letters with a friend without wanting him to be present, but we might do history for quite some time without ever wishing to just see the things we study.