Scientists must accept facts even when they would like them to be different. They must strive to distinguish between what they see and what they wish to see --- for humanity's capacity for self-deception is vast. People have traditionally tended to adopt general rules, beliefs, creeds, theories, and ideas without thoroughly questioning their validity and to retain them long after they have been shown to be meaningless, false, or at least questionable. The most widespread assumptions are the least questioned. Most often, when an idea is adopted, particular attention is given to cases that seem to support it, while cases that seem to refute it are distorted, belittled, or ignored. We feel deeply that it is a sign of weakness to "change out minds." Competent scientists, however, must be expert at changing their minds. This is because science seeks not to defend our beliefs but to improve them. Better theories are made by those who are not hung up on prevailing ones.
科学家必须接受事实，即使在他们希望事实不同时也必须如此。他们必须竭尽全力把他们看到的同他们希望看到的区分开来——因为人类具有极大的自欺能力。人们一贯倾向于未经彻底询问其是否正确，便采纳一般的规则、信仰、信念、理论和观点，而且在它们被证明是毫无意义的、错误的或者至少是可疑的之后，能长久地抱住它们不放。流传最广的假定是最少受到怀疑的。当某种观点被采纳之后，人们特别注意的往往是那些似乎是证实这一观点的事例，而似乎是驳斥它的事例则被歪曲、贬低或忽视。我们都深深感到，“改变看法”是一种虚弱的表现。然而，有能力的科学家必须善于改变看法。这是因为科学所追求的并不是维护我们的信念而是要改进我们的信念。只有那些不迷恋于流行理论的人才能创造出更好的理论来。