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False Effect

non causa pro causa

Description: Unlike the false cause, the false effect incorrectly assumes an effect from a cause.

Logical Forms:

X apparently causes Y.

Y is wrong.

Therefore, X is wrong.


X apparently causes Y.

Y is right.

Therefore, X is right.

Example #1:

Watching TV that close will make you go blind, so move back!

Explanation: The false effect from watching TV too closely is going blind.  For the most part, the threat that you will “ruin” your eyesight is an old wives tale, but it does have some credibility based on modern studies, but almost certainly, nobody is going blind from sitting too close unless they ram their eyes into the protruding knobs.  Anyway, the conclusion, “so move back!” is not warranted by the false effect.

Example #2:

Giving 10% of your income to the Church will free a child’s soul from Limbo into Heaven, so give your money!

Explanation: Centuries ago, the Church stopped accepting bribes to get loved ones out of Limbo, and very recently, in 2007, the Church made it more clear that Limbo was a theory and not an official doctrine of the Church, separating the Church from that belief.  As for the argument, the false effect of “freeing a child’s soul from Limbo” does not warrant the conclusion of giving your money.

Exception: A belief of an effect could be argued to be an actual effect.  Effects often can be supported empirically (scientifically), but they can also be claimed by “faith”, making them impossible to prove or disprove.


This a logical fallacy frequently used on the Internet. No academic sources could be found.

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