(also known as: persuasive definition fallacy, redefinition)
Description: Defining a term in such a way that makes one’s position much easier to defend.
A has definition X.
X is harmful to my argument.
Therefore, A has definition Y.
Before we argue about the truth of creationism, let’s define creationism as, “The acceptance of a set of beliefs even more ridiculous than those of flat-earthers.”
Before we argue about the truth of creationism, let’s define evolution as, “Faith in a crackpot theory that is impossible to prove with certainty.”
Explanation: It should be clear by the two examples who is defending what position. Both arguers are taking the opportunity to define a term as a way to take a cheap shot at the opponent. In some cases, they might actually hope their definition is accepted, which would make it very easy to defend, compared to the actual definition.
Exception: When a definition used is really an accurate definition from credible sources, regardless of the damage it might do to a position.
Tip: Do not accept definitions put forth by the opponent unless you researched your definition on your own, and agree.