G.K. Chesterton:

Reason is itself a matter of faith. It is an act of faith to assert that our thoughts have any relation to reality at all. If you are merely a sceptic, you must sooner or later ask yourself the question, "Why should anything go right; even observation and deduction? Why should not good logic be as misleading as bad logic? They are both movements in the mind of a bewildered ape?" The young sceptic says, "I have a right to think for myself." But the old sceptic, the complete sceptic, says, "I have no right to think for myself. I have no right to think at all. -G.K. Chesterton's Orthodoxy