Thomas Nagel's description of reason

Thomas Nagel described reason as follows:
Reason, if there is such a thing, canserve as a court of appeal not only against the received opinions and habits of our community, but also against the peculiarities of our personal perspective. It is something each individual can find within himself, but at the same time has universal authority. Reason provides, mysteriously, a way of distinacing oneself from common opinion and received practices that is not a mere elevation of individuality—not a determination to express one’s idiosyncratic self rather than go along with everyone else. Whoever appeals to reason purports to discover a source of authority within himself that is not merely personal, societyal, but universal, and that should persuade others who are willing to listen to it.

Nagel also maintains that both affirming and denying the existence of reason raises philosophical problems.