Calling it an "informal fallacy" would still make it not a logical fallacy. The slippery slope argument is correct whenever the premises are satisfied.
It's possible in some cases that the conclusion is weak, e.g. if Y is a negative outcome but not a very significant one, but that doesn't make it a fallacy and in particular doesn't justify dismissing arguments of that form as a fallacy when X does make Y significantly more likely and Y is a significant concern.
> It's possible in some cases that the conclusion is weak
Not only weak, but completely void, which is why it is an informal fallacy, and thus a fallacy, if I understand it right. You're correct that it's not a logical fallacy specifically, and I do see in retrospect that that was the point of contention (in literal terms anyways). But I'm really not sure that it really was in literal terms you guys were talking, really didn't seem like it.
> Not only weak, but completely void, which is why it is an informal fallacy, and thus a fallacy
In those cases the premises wouldn't even be satisfied. It's like saying that "all men are mortal, Socrates is a man, therefore Socrates is mortal" is a fallacy because you're disputing that Socrates is a man rather than a fictional character in Plato's writings. That doesn't make the argument a fallacy, it makes the premise in dispute and therefore the argument potentially inapplicable, which is not the same thing.
In particular, it requires you to dispute the premise rather than the form of the argument.
You'll need to take this up with the entire field of philosophy, because in literature informal fallacies are absolutely an existing and distinct class of fallacies, with the slippery slope argument being cited among them: https://iep.utm.edu/fallacy/#H2
It's not just a Wikipedia thing or me wordsmithing it into existence. As far as I'm concerned though, arguments the premises of which are not reasonable to think they apply / are complete, or are not meaningfully possible to evaluate, are decidedly fallacious - even if they're logically sound.
> The fact that something is widely parroted doesn't mean it's correct
Argumentum ad populum [0] is itself an informal fallacy, as described on both of our links. What I said wasn't an argumentum ad populum anyways: we're discussing definitions, and definitions do not have truth values.
> But all arguments depend on their premises being correct
But not all incorrect premises are formulated in a reasonable manner. There are degenerate premises that have telltale signs of being misguided. These would be what make informal fallacies. In a way, you could think of them as being incorrect about the premises of what counts as sound logic.
In fact, I ran into this the other day here when while someone said something potentially true, they were also engaging in a No True Scotsman fallacy (also an informal fallacy). One of them claimed that "if it's a fallacy, it's nonsensical to call it true" - except no, that's not the point. The statement can absolutely be true in that case, it's the reasoning that didn't make sense in context. Context they were happy to deny of course, because they were not there to make people's days any better.
Similar here: the slippery slope can be true and real, it's just fallacious to default to it. Conversely [0], it is absolutely possible that people all think the same thing, are actually right, and some other thing becomes true because of it, just super uncommon, so it is fallacious to invert it.
> Argumentum ad populum [0] is itself an informal fallacy, as described on both of our links.
Which gets to the difference between one and the other.
"This is correct because everybody says it is" is a fallacy because it can be true or false independent of whether everybody says it is or not. Even if the premise is true, the conclusion can be false, or vice versa.
Whereas if the premises that X likely leads to Y and Y is bad are both true, then the conclusion that X likely leads to something bad is not independent.
> What I said wasn't an argumentum ad populum anyways: we're discussing definitions, and definitions do not have truth values.
Categories have definitions. Whether a particular thing fits into a particular category can be reasoned about, and a particular miscategorization being common doesn't make it correct.
> But not all incorrect premises are formulated in a reasonable manner. There are degenerate premises that have telltale signs of being misguided. These would be what make informal fallacies. In a way, you could think of them as being incorrect about the premises of what counts as sound logic.
The general form of informal fallacies is that they take some reasoning which is often true (e.g. if everybody believes something then it's more likely to be true than false) and then tries to use it under the assumption that it's always the case, which is obviously erroneous, e.g. the majority of people used to think the sun revolved around the earth.
The category error with slippery slope is that the probability is part of the argument. If 60% of the things people believe are true, that doesn't tell you if "sun revolves around the earth" is one of those things, so you can't use it to prove that one way or the other.
Whereas arguing that taking on a 60% chance of a bad thing happening is bad isn't a claim that the bad thing will definitely happen.
> is a fallacy because it can be true or false independent of whether everybody says it is or not
Except of course when there is a dependence between the trueness of the statement and how many people are saying it. For example, if I bring up that a certain taxonomization exists and is established, it is pretty crucial for it to be popularly held, otherwise it would cease to both exist and be established.
> Whether a particular thing fits into a particular category can be reasoned about, and a particular miscategorization being common doesn't make it correct.
But you reject the category of informal fallacies being fallacies overall, despite them being definitionally fallacies, no?
It's possible in some cases that the conclusion is weak, e.g. if Y is a negative outcome but not a very significant one, but that doesn't make it a fallacy and in particular doesn't justify dismissing arguments of that form as a fallacy when X does make Y significantly more likely and Y is a significant concern.