Reason for the Species; Faith for the Man

Reason is essentially public. Anyone, assuming adequate intelligence, is able to follow a line of logic. There may be stumbling blocks: maybe he doesn't understand the vocabulary, maybe he is too emotionally invested in a contrary view, maybe he is too preoccupied to give the line the adequate attention it requires, but it is all available to him if he wants to acquire it.

This is why argument, discussion, and instruction is possible. We're all speaking the language, we all understand how it works, and if we do not understand it we can pick it up. Language is not private, neither is reason. Even particular epistemologies are understandable by all.

Faith is essentially private, though. It is not communicated. We think it can be, hence theology. Theology is the error produced when one uses reason to talk about things that can not be talked about. We may object and say that we need a church, that faith can not be private, it is communal! But the church is there for support and fellowship, when the leaders speak they are either speaking from reason (that is, trying to teach morality, which is hardly their special domain) or they are talking their particular brand of theology which is probably being contradicted at that very moment by the church down the street.

Reason belongs to the species; faith belongs to the individual. Madness also belongs to the individual.