When one admits that nothing is certain one must, I think, also admit that some things are much more nearly certain than others. It is much more nearly certain that we are assembled here tonight than it is that this or that political party is in the right. Certainly there are degrees of certainty, and one should be very careful to emphasize that fact, because otherwise one is landed in an utter skepticism, and complete skepticism would, of course, be totally barren and completely useless.

Bertrand Russell (1872-1970) English mathematician and philosopher

“Am I an Atheist or an Agnostic?” sec. “Skepticism” (1949)
    (Source)

Originally given as a speech, "Agnosticism v. Atheism," Rationalist Press Assoc. Annual Dinner, London (1949-05-20); then printed as "Agnosticism v. Atheism," The Literary Guide and Rationalist Review (1949-07); then released as an essay under this title later in 1949.