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Comment by thisiscorrect | Hacker News Reader

I've never understood how a slippery slope argument is a fallacy, let alone a logical fallacy (like false syllogism or no true scotsman). The idea is essentially looking at current trends and extrapolating into the future. No prediction is necessarily correct, but it's not necessarily wrong either.

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The other comment has it, but two ways to think about it. "If I have one glass of water I might have another. Then another. And so on until I drown myself."

The main one though is assuming the parties cant adjust course part way though. "If we turn this ship this way we will crash into that island in two days!"

Extropolation is different as it takes into a account changes in behaviour and real world constraints

Yes, the extrapolation is often applied to people who really want to achieve one thing going in a particular direction, so it makes sense there. "You want to do X which is not terrible evil in itself, but if we let you, you'll want to do more things like X so we don't want that precedent"

That’s because it’s not automatically a fallacy. That’s a huge misconception.

> Logic and critical thinking textbooks typically discuss slippery slope arguments as a form of fallacy but usually acknowledge that "slippery slope arguments can be good ones if the slope is real—that is, if there is good evidence that the consequences of the initial action are highly likely to occur. The strength of the argument depends on two factors. The first is the strength of each link in the causal chain; the argument cannot be stronger than its weakest link. The second is the number of links; the more links there are, the more likely it is that other factors could alter the consequences."

It's because it's not an argument about the thing itself, it's an argument about a speculative thing that might happen. You can rebut it by just saying "but that won't happen". So using it in an argument kinda inherently gets you into an unprovable realm.

In various avenues where it commonly appears (guns, gay marriage, speech, privacy, etc) it's particularly unhelpful because the US typically lags other western nations on this stuff.

So an opposition that relies on "what if" scenarios to oppose progressive change is often one which is either unaware-of or has explicitly looked at other nations that are 10-50 years ahead on whatever the policy is, and discovered that enacting step X did not, in fact, lead to a downward spiral into nightmare scenario Y.

The problem is in how people use it.

If I say it's a slippery slope from A to B, what that's supposed to mean is that A being true will increase the risk of B becoming true if other things happen as well.

How it's often used though is that if A is a slippery slope to B then A is equivalent to B, and thus any issue with B is an unavoidable issue for A. And of course it gets worse when people jump from A to Z.

When you do it, it's the slippery slope logical fallacy. When I do it, it's logical induction, a necessary component of reasoning about the world.

But if everyone started correctly applying logical induction for every piece of reasoning, we'd all become mindless robotic automata, hardly better than giant abacuses, and art, hope and love would die.

> logical induction, a necessary component of reasoning about the world

Bah! You're only saying that because induction worked the last n times ;)

It's not a fallacy. It's more like a "logic smell" that means you should look closer to see if the arguer is jumping to conclusions. If they are you should still investigate, e.g. the chain of events they are describing may have actually happened in history or could be related from personal experience. Affording them merit based on that is probably questionable in terms of formal logic, but it might not be unwise.

Everyone uses slippery slope reasoning in their personal lives, because it's a completely valid form of reasoning in the real world.

Otherwise we'd be fine with the concept of e.g. trying methamphetamine just a few times and then planning to stop.

"Slippery Slope" can be and is used to object to absolutely any action at all.

This argument is a slippery slope implying any comment can be objected.

IMO Slippery slope arguments can definitely be valid. Slippery slope fallacies are failed slippery slope arguments. To successfully argue for the slippery slope, one needs to actually argue that the slope exists and will lead to the ultimate consequence with meaningful certainty. The tactic is so common in sophistry: merely stating A -> B -> C -> D -> "nuclear holocaust" does not make it so.

Like... if an event has an 80% chance of occurring as a result of an action, it seems that the event is highly likely to occur. If this has an 80% chance causing of a different event, which has an 80% chance of a different event, leading to an 80% chance of a different event, the probability of the final event from a point in time before the first event occurred would be 41%.

Arguments are a construction of information intended to induce an understanding of probability among others, and skipping steps along the way weakens trust in that conclusion.

A slippery slope argument assumes the maximum degenerate outcome of sliding down the slope as a certainty, that no one will be able to correct for, mitigate or reverse the slide when it starts. That's what makes it a fallacy - it's a thought terminating cliche meant to eliminate the possibility of nuance, as any middle ground is implicitly part of the slope.

Otherwise, it's just an argument that risk exists, which is obvious and uninteresting.

Slippery slope is a valid political tactic for those outside the Overton window.

It's effective, because markets (including the marketplace of ideas) are irrational and bad faith tactics are often more effective at influencing people (at least in the short term) than reason and verifiable fact. I wouldn't consider it valid, though.

"Valid", as in, "it works".

Or if it's really bad, they make up entirely fanciful slopes that you could fall down.

Does it count as a slippery slope fallacy if the government argues that not stopping encrypted communications will result in terrorists killing your grandma? Because I heard that one a lot when Bush was president and they haven't really ever stopped using it. Is there a better fallacy for that example?

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