Recently I came upon a collection of quotes by different well-known philosophers about rationality. They were in a peculiar order that evokes amusement. (Ref. The Art of Procrastination, A Guide to Effective Dawdling, Lollygagging and Postponing - John Perry)
Man is a rational animal. - Aristotle
Man is not a rational animal, he is a rationalizing animal. - Robert Heinlein
Man is a rational animal who always loses his temper when he is called upon to act in accordance with the dictates of reason. - Oscar Wilde
It has been said that man is a rational animal. All my life I have been searching for evidence which could support this. - Bertrand Russel