To avoid the various foolish opinions to which mankind are prone, no superhuman genius is required. A few simple rules will keep you, not from all error, but from silly error.
If the matter is one that can be settled by observation, make the observation yourself. Aristotle could have avoided the mistake of thinking that woman have fewer teeth than man, by the sumple device of asking Mrs.Aristotle to keep her mouth open while he counted.He did not do so because he thought he knew. Thinking tht you know when in fact you don't is a fatal mistake, to which we are all prone.
Many matters, however are less easily brought to the test of experiebce. If, like most of mankind , you have passionate convictions on many such matters, there are ways in which you can make yourself aware of your own bias. If an opinion contrary to your own makes you angry, that is a sign that you are subconsciously aware of having no good reason for thinking as you do . If someone maintains that two and two are five, or that Iceland is on the equator, you feel pity rather than anger, unless you know so little of arithmetic or geography that his opinion shakes your own contrary conviction. The most savage controversies are those about matters as to which there no good evidence either way. Persecution is used in theology, not in arithmetic, because in arithmetic there is knowledge , but in theology there is only opinion.
So whenver you find yourself getting angry about a difference of opinion, be on your guard; you will probably find , on examination, that you belief is going beyond what the evidence warrants.
From How to Avoide Foolish Opinions by Bertrand Russell
持有各种各样愚蠢的见识乃人类的通病。要想避免这种通病，并不需要过人的天赋。下面有几项简单原则，虽然不能保证你不犯任何错误，却可以保证你避免一些可笑的错误。
如果一个问题单凭观察就可以解决的话，就请您亲自观察一番。亚里士多德误以为妇女牙齿的数量比男人少。这种错误，他本来是可以避免的，而且办法很简单。他只需要请他的夫人把嘴张开亲自数一数就行了。但他却没有这样做，原因是他自以为是。自以为知道而实际上并不知道，这是我们人人都容易犯的一种致命错误。
不过，也存在许多事情不那么容易用经验加以检验。如果你像大多数人一样在这类事情上颇为激烈的主张，就有一些办法可以让你意识到自己的想法是有偏颇的。如果你一听到一种与你相左的意见就发怒，就表明，你已经下意识地明白自己坚持的那种看法并没有充足的理由。如果某个人硬要说2加2等于5，或者说冰岛位于赤道，那么你会感到怜悯而不是愤怒，除非你自己对数学和地理也是知之甚少，因而他的看法竟然动摇了你的立场。最野蛮的争议是关于那些不能证实或者证伪的事件。迫害事件仅仅发生在神学领域而不见于数学领域，因为数学问题是知识问题，而神学问题则是见解问题。
所以，无论什么时候，只要发现自己对不同的意见发起火来，你就要当心了，因为一经经验，你的信念并没有足够的依据。
节选自罗素的《如何避免愚蠢的见识》
