Also called Ad Consequentiam. Includes Wishful Thinking.
The Appeal to the Consequences of a Belief is a fallacy that comes in the following patterns:
This line of "reasoning" is fallacious because the consequences of a belief have no bearing on whether the belief is true or false. It is important to note that the consequences in question are the consequences that stem from the belief. It is important to distinguish between a rational reason to believe (evidence) and a prudential reason to believe (motivation). A rational reason to believe is evidence that objectively and logically supports the claim. A prudential reason to believe is a reason to accept the belief because of some external factor (such as fear, a threat, or a benefit or harm that may stem from the belief) that is relevant t what a person values but is not relevant to the truth or falsity of the claim.
The nature of the fallacy is especially clear in the case of Wishful thinking. Obviously, merely wishing that something is true does not make it true. This fallacy differs from the Appeal to Popularity/Belief in that the Appeal to Popularity/Belief involves taking a claim that most people believe that c is true to be evidence for c being true.
You can't agree that evolution is true, because if it were, then we would be no better than monkeys and apes.
You must believe in God, for otherwise life would have no meaning.
Perhaps, but it is equally possible that since life has no meaning that God does not exist.
"If sixteen-headed purple unicorns don't exist, then I would be miserable, so they must exist"
"God must exist! If God did not exist, then all basis for morality would be lost and the world would be a horrible place!"
"It can never happen to me. If I believed it could, I could never sleep soundly at night."
"I don't think that there will be a nuclear war. If I believed that, I wouldn't be able to get up in the morning. I mean, how depressing."
"I acknowledge that I have no argument for the existence of God. However, I have a great desire for God to exist and for there to be an afterlife. Therefore I accept that God exists."
Identify the consequences to and argue that what we want to be the case does not affect what is in fact the case.