Ad Hoc ("To This") reasoning is where someone fails to understand that there is a difference between argument and explanation. The Ad Hoc fallacy is to give an after-the-fact explanation which doesn't apply to other situations. If we're interested in establishing A, and B is offered as evidence, the statement "A because B" is an argument. If we're trying to establish the truth of B, then "A because B" is not an argument, it's an explanation. It's a very common sight in justifying edits aimed at any supposedly negative trope, particularly if that edit calls upon things that might have happened to cause the item described.
Looks like this fallacy, but isn't:
- When used to argue against "A because B" when C, D, or E could also have caused B. Explanation: there are two types of causes: necessary and sufficient. A necessary cause must exist for the effect to happen, but may not be enough by itself to cause the effect. A sufficient cause can cause the effect all by itself, but may not have to exist for the effect to happen. Oxygen is a necessary cause for fire; no oxygen, no fire, regardless of anything else that might be going on. Oxygen is not a sufficient cause for fire; lots of other things have to happen as well as there being oxygen around. Decapitation is a sufficient cause of death; decapitation will kill you without anything else being required. It is not a necessary cause of death; there are all kinds of causes of death which leave the head attached.
- A simple way to see this is to remember to SiN, where the Sufficient Implies Necessary. In other words, review the sufficient and necessary statements as an If-then statement, then the sufficient should naturally come first. If you are decapitated, then you will die. (Death as necessary for decapitation, decapitation is sufficient for death.) If you eat a thousand donuts then you will gain weight. (A thousand donuts will surely make you heavier - in other words, is sufficient, but it is hardly necessary for making you heavier.) If you browse TV Tropes, then you will waste hours on the internet. (Directing someone to TV Tropes is a sufficient for them wasting hours upon hours online, but there are addictive sites out there.) As a tool, it is useful for conceptualizing the difference, but do not argue logically based on it.