Argument from Adverse Consequences

This fallacy occurs when negative results would occur if the opposition were correct.  Often, this is used as a defense mechanism.  Conversely, the opposite (when positive results occur if the arguer is correct) is equally fallacious.

Example: The water technician said that test results for my well water just came back positive for lethal amounts of the poison arsenic.  If this is true, my entire family has been drinking arsenic-laced water since the chemical spill yesterday, and we are all going to die in the next few hours.  The water technician is obviously wrong because I don't want to die.

Example: 

Example: Mr. X. is the defendant in the well-known murder trial.  If we do not find Mr. X. guilty of murder, others will not be discouraged from committing murder, and they will go out and murder at will. 

(Adapted from: http://www.brainpickings.org/index.php/2014/01/03/baloney-detection-kit-carl-sagan/)