False Premises

Deduction tells you what follows from your premises, but does not tell you whether your premises are true… It can, however, enable you to know that your premises are false. It may happen that the consequences of your premises can be disproved, and in that case your premises must be more or less wrong. Bishop Colenso, in his endeavor to convert the Zulus, translated the Bible into their language. They read it with an open mind, but when they came to the statement that the hare chews the cud they informed him that this was not the case. He was a bookish man, unfamiliar with the habits of hares, but at the instigation of the Zulus he observed a hare and found they were right. This caused him to have ‘doubts,’ which led the authorities to deprive him of his salary.

— Bertrand Russell