Straight and Crooked Thinking: avoidable errors

People make avoidable errors because they fail to reason correctly. These mistakes are not due to lack of intelligence or facts but to faulty habits of thinking, and nearly everybody makes them.

Why people make avoidable errors

1. Careless use of words. The same word is used by different people with different meanings (for example "intelligence" or "oxygen"), and a single word is used for several different things. Arguments then become confused.
2. Failure to distinguish varieties. Things that differ are treated as the same because they have the same name.
3. Emotion and prejudice. People accept what they wish to believe and reject facts which they dislike.
4. Hasty generalisation. Conclusions are drawn from too few cases.
5. Confusing cause and effect. Because one event follows another, people assume the first caused the second.
6. Accepting authority or common opinion without testing the claim.

Who makes them

• All kinds of people: individuals and groups, scientists and non-scientists alike. Ordinary people are especially likely to be confused by technical words used in daily speech, but even trained scientists may fall into error when they stop checking their reasoning.

Remedy

Define terms clearly, look for evidence, test conclusions, separate fact from feeling and remain willing to correct oneself. Straight thinking is a skill that can be learnt and practised.