“It is not what the man of science believes that distinguishes him, but how and why he believes it. His beliefs are tentative, not dogmatic; they are based on evidence, not on authority or intuition.”

“The essence of the Liberal outlook lies not in what opinions are held, but in how they are held: instead of being held dogmatically, they are held tentatively, and with a consciousness that new evidence may at any moment lead to their abandonment.”

“The extent to which beliefs are based upon evidence is very much less than believers suppose. Take the kind of action which is most nearly rational: the investment of money by a rich City man. You will often find that his view (say) on the question whether the French franc will go up or down depends upon his political sympathies, and yet is so strongly held that he is prepared to risk money on it.”

“What we firmly believe, if it is true, is called knowledge, provided it is either intuitive or inferred (logically or psychologically) from intuitive knowledge from which it follows logically. What we firmly believe, if it is not true, is called error. What we firmly believe, if it is neither knowledge nor error, and also what we believe hesitatingly, because it is, or is derived from, something which has not the highest degree of self-evidence, may be called probable opinion. Thus the greater part of what would commonly pass as knowledge is more or less probable opinion.”

“If a man is offered a fact which goes against his instincts, he will scrutinize it closely, and unless the evidence is overwhelming, he will refuse to believe it. If, on the other hand, he is offered something which affords a reason for acting in accordance to his instincts, he will accept it even on the slightest evidence. The origin of myths is explained in this way.”

“Man is a credulous animal, and must believe something; in the absence of good grounds for belief, he will be satisfied with bad ones.”

“Intellectually, what is stimulating to a young man is a problem of obvious practical importance. A young man learning economics, for example, ought to hear lectures from individualists and socialists, protectionists and free-traders, inflationists and believers in the gold standard. He ought to be encouraged to read the best books of the various schools, as recommended by those who believe in them. This would teach him to weigh arguments and evidence, to know that no pinion is certainly right, and to judge men by their quality rather than by their consonance with preconceptions.”