Moral scepticism can no more be refuted or proved by logic than intellectual scepticism can. When we stick to it that there is truth (be it of either kind), we do so with our whole nature, and resolve to stand or fall by the results. The sceptic with his whole nature adopts the doubting attitude; but which of us is the wiser, Omniscience only knows.
William James, The Will to Believe, Human Immortality and Other Essays in Popular Philosophy
doubt, truth