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Wrong direction is a logical fallacy of causation where cause and effect are reversed. The cause is said to be the effect and vice versa.

For instance, a tobacco company executive once suggested that cancer caused smoking as a matter of pain relief, to explain the high correlation between them.^{[citation needed]}

Another obvious example:

Driving a wheelchair is dangerous, because most people who drive them have had an accident.

In other cases it may simply be unclear which is the cause and which is the effect. For example:

Children that watch a lot of TV are the most violent. Clearly, TV makes children more violent.

This could easily be the other way round; that is, violent children like watching more TV than less violent ones.

Likewise, a correlation between recreational drug use and psychiatric disorders might be either way around: perhaps the drugs cause the disorders, or perhaps perople use drugs to self medicate for preexisting conditions.

A historical example of this is that people in the Middle Ages were convinced that lice were beneficial to your health, since there would rarely be any lice on sick people. The reasoning was that the people got sick because the lice left. The real reason however is that lice are extremely sensitive to body temperature. A small increase of body temperature, such as in a fever, will make the lice go look for another host. The medical thermometer had not yet been invented, so this increase in temperature could not be noticed. Noticeable symptoms came later, giving the impression that the lice left before the person got sick.

In other cases, two phenomena can each be a partial cause of the other; consider poverty and lack of education, or procrastination and poor self-esteem.

• Joint effect
• Spurious relationship