Murphy’s Law on Slippery Slopes
I’ve argued before that logical fallacies get a bad rap, in no small part because few understand that “fallacy” means one thing to us commoners (roughly, “a load of horse crap”) and something quite different to logicians (equally roughly, “any inference that runs a .0000000000001% risk of being wrong”). Rational debates quickly turn irrational this way:
A: I think X is an idea whose time has come.
B: Are you nuts? X by itself might not be that big of a deal, but once we open the door to X, how do we keep out Y?
A: X is not Y. Just because X happens, it doesn’t logically follow that Y will. That’s a logical fallacy. Neener.
B: Neato. But formal logic aside, we both know that the only reason we are presently assured that Y will never happen is because Rule Z is in place, which also precludes X. Once we let in X, Z goes with it, leaving the door wide open for Y.
A: Bbbbbbbuttttttt… my logic teecher sez slippery slope is a fallacy. So there.
Certainly it is a problem to confuse the common-sense observation that X may lead to Y with the non sequitur that it necessarily will. Well-crafted slippery slope arguments don’t do that. Instead, they merely note, correctly in some instances, that allowing X makes Y more likely to occur than it otherwise would be. Which, in my above example, was basically the point B was trying to make.
The real fallacy (as the word is used in common parlance, not formal logic) in slippery slope is built right into the analogy of slopes: they all go downhill. Can a little gun control lead to mass confiscation? That depends. If you’re a staunch defender of the Second Amendment, you probably think the answer is yes. But if you’re one of those dweebs who actually thinks mass confiscation is a good idea, you’re probably equally convinced that the answer is no. Similarly, if you are a gun grabber, you probably think that seeing the U.S. Supreme Court uphold Parker/Heller in any form will cause the entire world of gun “sanity” to unravel, while the gunnies think it won’t accomplish anything.
September 19th, 2007 at 10:07 am
[...] Xrlq gets his logic on. [...]
September 19th, 2007 at 10:44 am
D’oh.
I didn’t say it wouldn’t accomplish anything, or about the long-term ramifications, but just that the court case itself would only apply meaningfully to DC’s gun ban (or potential federal bans). Even if we win incorporation in a separate case, it would still only apply against a very limited area.
Good point about the fallacy fallacy, though. Too many people ignore that fallacies just show the failure of one argument, not of the assumption, and that each fallacy is a lot more limited than the normal assumption is (it’s an ad hominem fallacy to claim gun control is bad because Hitler did it, but not one to show how it didn’t work out well when Hitler did it).
September 19th, 2007 at 11:11 am
Slippery Slope Notes
http://www.two–four.net/weblog.php?id=P3197
At your service.
September 19th, 2007 at 11:15 am
As for the DC decision…whatever it turns out to be will be limited as much as possible.
1st amendment decisions seem to always be interpreted as widely as possible. I don’t see that happening with 2A decisions, altho they’re haven’t been many.
September 19th, 2007 at 12:51 pm
As I pointed out to my friends a few weeks ago, the whole point of the slippery slope argument is that if there are not differences in principle between positions A, B, C, etc., then the differences in degree are completely arbitrary. It drives me nuts that some people think this is a fallacious argument.
September 19th, 2007 at 4:52 pm
Well, it is a fallacy : just because X is more similar to Y than W, doesn’t mean action X will lead to Y or Z. That itself, is the fallacy, and it’s remarkably common.
As soon as you present a reason, you’re no longer using the slippery slope argument, and instead relying on… well, usually appeal to emotion, appeal to authority, or non sequitur, usually, but sometimes we slip up and toss a logical statement in.
September 19th, 2007 at 9:04 pm
Gattsuru is right. It fails both the test of sufficiency and the test of necessity.
September 20th, 2007 at 10:28 am
Billy Beck’s take on the “slippery slope” fallacy: “Slippery Slope” Notes.
He has a good argument.
September 20th, 2007 at 1:27 pm
Wulf, the fallacy lies in the fact that while it is often true that allowing A now will increase the odds of B happening later, it is also possible to have A and not end up with B later. Since A does not logically entail B, it is considered a “fallacy.” However, that doesn’t mean the argument is wrong, as A may very well lead to B, even if it’s not guaranteed to.
My point here, though, is that the wish factor seems to be at play, i.e., no one ever expects A to lead to B unless also they think B is bad. In reality, of course, “good” slopes are no more likely to be slippery than “bad” ones are.