"If I hold an opinion only because someone else told me it was true, and I myself do not have any other reason for thinking it to be true, then that is a mere opinion on my part. The statement may be in fact be true. That does not make it any the less a mere opinion. So far as affirming it is concerned, I have no grounds that provide me with reasons for thinking it to be true apart from the authority of someone else." Mortimer Adler in Aristotle for Everyone.