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Some Slopes Are, In Fact, Slippery


The slippery slope argument is common. We are warned against (A) because it will lead through (B) and (C) to something really crappy at (K) or (L).

“Don’t go near cannabis, because after one whiff, you’ll eventually end up dead in some toilet stall from a heroin overdose”

“If you listen to heavy metal music, you’ll end up a murderer and burn in hell for eternity.”

By more strict logic, each point in the progression must be weighed on its own merits. (A) stands alone. (B) stands alone. It’s not reasonable to reject (A) or (B) because of (K) or (L).

Labeling an argument as “slippery slope” is used to weaken or undercut that argument. Hopefully, the above examples seem ridiculous. Heavy Metal music is not a precusor to murder and hell.

But what if someone had said, “No-smoking sections on jetliners are just a first step. Eventually they’ll ban smoking at restaurants and in your own apartment.” Or, “Once we free the slaves, the coloreds will eventually be able to achieve political equality. One of ’em might even become President.”

Maybe the slippery slope is not a logical fallacy. Or, not necessarily a fallacy:

Modern usage includes a logically valid form, in which a minor action causes a significant impact through a long chain of logical relationships. Note that establishing this chain of logical implication (or quantifying the relevant probabilities) makes this form logically valid. The slippery slope argument remains a fallacy if such a chain is not established.

What matters is the logic of slipperiness. If the progression can be demonstrated through good reasoning, then the slippery slope is not a fallacy.

There is certainly room to debate a logical chain of events. Cannabis does sometimes lead to heroin. That some people do follow such a path is not proof that all will. The logical causation must be established at (B), (C), and (D). That some do not follow the path to destruction suggest that there are weak links or bad thinking somewhere in those middle steps.

An argument cannot be simply dismissed as a fallacious “slippery slope”. When someone uses such rhetoric, the slope itself become the argument. It’s no longer just about (A). Some, many, most assertions of a slippery slope are probably true. In order to rebut or counter-argue, one must do more than just yell “slippery slope!” and declare victory. The slope must be shown to be non-slippery.

When your Representative says there are no Death Panels in the legislation (currently a hot topic) and you can keep your doctor, he’s arguing (A) alone. And he’s being strictly reasonable. When he asserts that Death Panels are just fear-mongering and slippery slope nonsense, you can explain that some slopes are, in fact, slippery. When government decides which treatments are worth paying for, that choice will lead to people not getting care and then dying.

It is also valuable to note that good intentions do not negate a slippery slope. Depending on the progression of causation, a noble (A) may result in a hideous (Z). The yell that warns someone about a falling icicle may cause an avalanche that wipes out a town.