The fallacy of appeal to emotion occurs when an arguer uses emotive language or emotionally charged anecdotes for argumentative purposes, without demonstrating any causal or logical connection to the conclusion being asserted. It is a logical fallacy even if the emotions are natural and appropriate to the topic, and this is not because emotional content is wrong or bad, but rather because emotion is not not the same thing as logic.

Here is an example:

A prosecutor tells the jury: "If you have any humanity at all, then you cannot even consider letting the defendant walk free, once you've seen these pictures of the horrors, the bloody knife, and the devastation of the victims of this terrible crime."

The depiction of these things can raise sorrow, sympathy, and anger in the jurors -- but does nothing to establish the guilt of the defendant.

Image Credit: Wannapik under CC BY 3.0