Another obvious example:
In other cases it may simply be unclear which is the cause and which is the effect. For example:
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 people 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. One making an argument based on these two phenomena must however be careful to avoid the fallacy of circular cause and consequence. Poverty is a cause of lack of education, but it is not the sole cause, and vice versa.
WIPO PUBLISHES PATENT OF WILHELM SCHRODER, TECHNISCHE UNIVERSITAT DORTMUND FOR "METHOD FOR DETECTING AND WARNING OF DRIVERS DRIVING IN THE WRONG DIRECTION AND REPORTING AND WARNING SYSTEM FOR DRIVERS DRIVING IN THE WRONG DIRECTION" (GERMAN INVENTORS)
Jan 26, 2012; GENEVA, Jan. 26 -- Publication No. WO/2012/000651 was published on Jan. 05. Title of the invention: "METHOD FOR DETECTING AND...