Definition of the extended analogy fallacy


The fallacy of the Extended Analogy often occurs when some suggested general rule is being argued over. The fallacy is to assume that mentioning two different situations, in an argument about a general rule, constitutes a claim that those situations are analogous to each other.

Every time an analogy is used it is used to state that A is similar to B in a particular way. It does not (necessarily) insinuate that they are alike in any other way. However, often opponents will attempt to attribute your use of the analogy to extend it to something not analogous as proof of your lack of logic.

Examples

Here's real example from an online debate about anti-cryptography legislation:
"I believe it is always wrong to oppose the law by breaking it."
"Such a position is odious: it implies that you would not have supported Martin Luther King."
"Are you saying that cryptography legislation is as important as the struggle for Black liberation? How dare you!"

"The slaughter of billions of chickens each year is morally wrong. Like the Nazi holocaust."
"Are you saying that chickens are as important as humans? How dare you!"