Also called Poisoning the Well or Genetic Fallacy.
The Appeal to Spite is a fallacy in which spite is substituted for evidence when an "argument" is made against a claim. This line of "reasoning" has the following form:
This sort of "reasoning" is fallacious because a feeling of spite does not count as evidence for or against a claim. Of course, there are cases in which a claim that evokes a feeling of spite or malice can serve as legitimate evidence. However, it should be noted that the actual feelings of malice or spite are not evidence.
"Don't listen to him, he's a scoundrel."
"Before turning the floor over to my opponent, I ask you to remember that those who oppose my plans do not have the best wishes of the university at heart."
You are told, prior to meeting him, that your friend's boyfriend is a decadent wastrel. When you meet him, everything you hear him say is tainted.
"Bill claims that the earth revolves around the sun. But remember that dirty trick he pulled on you last week. Now, doesn't my claim that the sun revolves around the earth make sense to you?"
Bill: "I think that Jane did a great job this year. I'm going to nominate her for the award."
Dave: "Have you forgotten last year? Remember that she didn't nominate you last year."
Bill: "You're right. I'm not going to nominate her."
Jill: "I think Jane's idea is a really good one and will really save a lot of money for the department."
Bill: "Maybe. Remember how she showed that your paper had a fatal flaw when you read it at the convention last year..."
Jill:"I had just about forgotten about that! I think I'll go with your idea instead."
Bill: "Boy, that professor is a real jerk. I think he is some sort of eurocentric fascist."
Prof. Jones: "...and so we see that there was never any 'Golden Age of Matriarchy' in 1895 in America."
Bill: "See what I mean?"
Jill: "Yeah. There must have been a Golden Age of Matriarchy, since that jerk said there wasn't."
Jill: "I think I'll vote for Jane to be treasurer of NOW."
Vicki: "Remember the time that your purse vanished at a meeting last year?"
Vicki:"Well, I just found out that she stole your purse and stole some other stuff from people."
Jill: "I'm not voting for her!"
In this case, Jill has a good reason not to vote for Jane. Since a treasurer should be honest, a known thief would be a bad choice. As long as Jill concludes that she should vote against Jane because she is a thief and not just out of spite, her reasoning would not be falacious.