The fallacy of the single cause, also known as joint effect or causal oversimplification, is a logical fallacy of causation that occurs when it is assumed that there is a single, simple cause of an outcome when in reality it may have been caused by a number of only jointly sufficient causes.

Often after a tragedy it is asked, "What was the cause of this?" Such language implies that there is one cause, when instead there were probably a large number of contributing factors. However, having produced a list of several contributing factors, it may be worthwhile to look for the strongest of the factors, or a single cause underlying several of them. A need for simplification may be perceived in order to make the explanation of the tragedy operational, so that responsible authorities can be seen to have taken action.

For instance, after a school shooting, editorialists debate whether it was caused by the shooter's parents, TV violence, stress on students, Hollywood or the accessibility of guns. In fact, many different causes — including some of those — may all have necessarily contributed. In addition, the music industry might claim that filesharing is the cause of a loss in profit whereas factors such as a growing videogame market and economic depression are also major factors in this.

Causal oversimplification is a specific kind of false dilemma where conjoint possibilities are ignored. In other words, the possible causes are assumed to be "A or B or C" when "A and B and C" or "A and B and not C" (etc.) are not taken into consideration.

The fallacy is alluded to (and refuted) in the 2001 film Ocean's Eleven:^[1]

Tess: You know what your problem is?

Danny: I only have one?

[edit] See also

• Spurious relationship

[edit] References

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