Slippery slope

Not to be confused with the continuum fallacy, which claims that two things that have no binary difference between them are the same thing.

Cogito ergo sum
Logic and rhetoric

Key articles

* Logical fallacy
* Syllogism
* Argument

General logic

* Exception that proves the rule
* Conditional fallacy
* Argumentum ad hominem
* Implicit bias
* Logically Fallacious
* Affirming the consequent

Bad logic

* Sheeple
* Not as bad as
* Big words
* Pragmatic fallacy
* Just asking questions
* 地下室论证

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“”Gene Gogolak: All right, then, let's see. Basketball hoop and backboard. Portable. Nope, I'm sorry. It's not allowed.

Mulder: You're kidding?
Gene Gogolak: I'm afraid not. Rules are rules. It may not sound like anything—a simple basketball hoop—but from there, it's just a few short steps to spinning daisy reflectors and a bass boat in the driveway.

Mulder: In other words: anarchy.

—The X-Files, Arcadia

While not a logical fallacy in itself, the slippery slope is a common variant on the argument from adverse consequences that asks for a prohibition or curtailment on something based on a series of undesirable results. This usually involves many steps, but only two are required. Usually the argument is put forth while ignoring possible mitigating factors, at which point it becomes a fallacy that's generally a somewhat-too-serious form of reductio ad absurdum.

The improperly applied slippery slope is a type of conditional fallacy.

## Contents

* 1 Alternate names
* 2 Form
* 2.1 Parade of the imaginary horribles
* 2.2 Appeasement
* 3 Examples
* 3.1 Fallacies
* 3.2 Casual
* 3.3 Semantic
* 4 Countering the slippery slope argument
* 5 Distinguishing fallacious and non-fallacious slippery slopes
* 6 See also
* 7 External links
* 8 Notes
* 9 References

## Alternate names[edit]

* domino effect
* gateway
* argument of the beard
* fallacious reductio ad absurdum

## Form[edit]

General form:

P1: If A, then B.

P2: If B, then C.

P3: If C, then D.
P4: D is undesirable.
C: Therefore, we should not do A.

Personal form:

P1: X happens.

P2: Y happens to some people that do X.

C: Therefore, Z will happen to all people that do X.

The two primary forms of the slippery slope argument are the logical form, in which acceptance of A must logically lead to acceptance of the undesirable B, and the psychological form, in which it is argued that the acceptance of A will, over time, lead people to be more willing to accept B. The logical form is further broken into two basic models. In the first, acceptance of B is a logical extension of A. The second, on the other hand, is known as the "arbitrary line" approach, in which it is argued that the acceptance of A will lead to the acceptance of A1, because A1 is not significantly different from A. This, in turn, will lead to A2, A3, and, eventually, to B. The first version can be shown to be logically valid if it can be shown that A logically entails B. The second version is only valid if it can be demonstrated that there is no clear point of demarcation between any two of the steps.

### Parade of the imaginary horribles[edit]

The parade of the imaginary horribles is the list of off-the-wall worst-case scenarios that opponents claim will occur after the legalization or acceptance of a prohibited activity (e.g. Rick Santorum's "man-on-dog sex" statement listed below). These scenarios usually say more about the psyches of the people who devise them than about the proponents for change. That being said, particularly in arguments of relatively pure law, such a "parade" can be a valid argument when the lines between this case and the "horribles" is relatively thin; take, for example, Kirtsaeng v. John Wiley & Sons, Inc., whose result partly turned on just such a "horrible" related to the Right of First Sale doctrine.

This term is attributed to former U.S. Supreme Court Justice William O. Douglas.

### Appeasement[edit]

The slippery slope argument may have some validity when the matter under discussion is a proposed political compromise with an opponent who has an agenda with many more items on it besides the one on the table. This is usually called appeasement; the underlying argument is that agreeing to the proposed "compromise" will not buy you peace, but only leaves you in a weaker position when confronted with the next demand.

## Examples[edit]

Former Senator Rick Santorum's belief that the US Supreme Court's decision on Lawrence v. Texas would eventually lead to the legalization of "man-on-dog" sex,[1] among other forms of sexual activity generally considered repulsive or obscene.[note 1]

It is also a common argument amongst opponents of drug or alcohol use, based on the idea that simply getting drunk or high once (or even just experiencing a little of the substance in question) inevitably leads to a raging addiction and a failed life (gateway drug theory).

### Fallacies[edit]

Logical fallacies are a dangerous thing.

First, you start off with something small, like an appeal to authority or "no true Scotsman."

Then, that leads to bigger ones, like an argumentum ad hominem, or begging the question.

That's not far away from post hoc ergo propter hoc or reductio ad Hitlerum.

Avoid logical fallacies at all costs; there's no telling where they'll lead!

### Casual[edit]

This is an example of the casual form:

'If I make an exception for you, I'd have to make an exception for the next person. Pretty soon, the rules would be meaningless.'

While this may not always be fallacious, sometimes A and B (i.e. making one exception and making many) are distinct enough that the argument becomes very weak. In this example, it is in fact possible to make an exception in one case only, as in an emergency, but not in usual cases.

### Semantic[edit]

The semantic form relies on the second of the two logical formulations of the slippery slope, as opposed to the psychological version. As an example of the semantic form:

'Remove one grain from a heap of sand, and you still have a heap. Remove another — still a heap. No matter how many you remove, you still have a heap of sand, even with one grain.'

Referred to as the "sorites paradox" or the "paradox of the heap", this argument is fallacious because there is no reason to suggest that a heap of sand is the same as one grain, just because there isn't an agreed upon minimum required grains of sand to constitute a "heap". That is, there exists a qualitative difference, despite no precise quantitative difference.

This formation is often used in ethical discussions regarding euthanasia and abortion. For example, Jonathon Glover expresses the argument as applied to euthanasia as:

'If it is allowable at birth for children with some grave abnormality, what will we say about an equally grave abnormality that is only detectable at three months? And another that is only detectable at six months? And another that is detectable at birth only slightly less serious? And another that is slightly less serious than that one?'[2]

As in all instances of this form, the argument only holds if there is no point at which a distinction can be drawn between different points. One general distinction is that of voluntary and involuntary euthanasia, and it can be argued that this formation of the slippery slope does not hold, as there comes a point where the child becomes able to express their own wishes. In abortion debates, a similar argument is proposed by arguing that there is no significant difference between a fetus at 14 days and a fetus at 15 days, or a fetus at three months and a fetus at three months and a day. This can be countered by pointing to significant changes in the development of the fetus that represent valid points of demarcation between stages of development. Which point of demarcation should be used is a very sensitive topic; a few parts of the world such as the US use "viability" as the point of demarcation (generally agreed to be "around" 24 weeks), others use "quickening" or when the fetus begins to move around as the demarcation (typically 18 weeks), but many are more strict.

## Countering the slippery slope argument[edit]

Frequently, the slippery slope has no evidence presented for why one would actually go down the slope, even if it is hypothetically possible. Pointing this out is sufficient to logically counter the argument. However, slippery slope arguments that involve no evidence can usually also slip the other way: if it is argued that gay marriage will lead to man-on dog sex, one could just as well argue that restricting gay marriage will lead to restrictions on other marriage, until it's banned altogether. After all, you may find it repugnant that two men marry, but other people find large age gaps to be disgusting, if we ban same-sex marriage, could we not also ban people from marriage based on age differences? If evidence is presented for why the slip could occur, the argument may be valid, in which case countering it requires refuting the evidence.

## Distinguishing fallacious and non-fallacious slippery slopes[edit]

An important note: Not all slippery slope arguments are fallacious, as the slippery slope is a conditional fallacy. What are the conditions to the fallacious use of the argument? There are a few major ones discussed above, but one particularly relevant marker is the question, "What lines separate this from the parade of horribles?" — the thicker and clearer the line, the more fallacious the purported "slippery slope" is.

Further, sometimes a purported historical "slippery slope" happens because the logic of the fundamental argument against the forbidden behavior starts falling apart. For example, the logic of outlawing certain drugs falls apart if the harm done by the drugs is vastly outweighed by the harm done by enforcement (as happened with alcohol Prohibition in the United States). Griswold v Connecticut was decided upon the idea that banning contraception would "allow the police to search the sacred precincts of marital bedrooms for telltale signs of the use of contraceptives",[3] ergo the law was too abhorrent to stand. Thus, an invocation of a historical slippery slope should be treated with some caution — they happen, they're quite real, but they can also happen because the initial position was unsustainable in the first place.

## See also[edit]

* Containment
* Continuum fallacy

## External links[edit]

* Slippery Slope, Fallacy Files
* "A Misconception About Slippery Slope Arguments" at The Volokh Conspiracy
* "The Mechanisms of the Slippery Slope" (PDF), Volokh again.
* "Same-Sex Marriage And Slippery Slopes" (PDF), Volokh discussing a particularly common (at the time) Slippery Slope argument, providing a good "as applied" case of his views.
* Your logical fallacy is slippery-slope, YLFI
* An X-Men comic which tells a powerful tale of anti-discrimination, but falls prey to the Slippery Slope

## Notes[edit]

1. ↑ As if sex itself isn't obscene on its own, by those people's standards. Though they do tend to have a lot of kids.

## References[edit]

1. ↑ A viewpoint on why something like this may not be so bad can be found here. WARNING: Fowl language.
2. ↑ Glover, Jonathan (1977). Causing Death and Saving Lives. Penguin Books. ISBN 0-14-022003-8. p. 165
3. ↑ Giswold V CT, Cornell Law School

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Articles about logical fallacies

Informal fallacies: |  Appeal to tradition • Appeal to novelty • Appeal to nature • Argument from morality • Argumentum ad martyrdom • Big words • Certum est quia impossibile est • Morton's fork • Friend argument • Exception that proves the rule • Extended analogy • Hindsight bias • Race card • Moralistic fallacy • Release the data • Gish Gallop • Terrorism-baiting • Uncertainty tactic • Greece-baiting • Ham Hightail • Red-baiting • Gore's Law • Nazi analogies • Mistaking the map for the territory • Red herring • Quidquid latine dictum sit, altum videtur • Presentism • Sunk cost • Two wrongs make a right • Flying carpet fallacy • My enemy's enemy • Appeal to ancient wisdom • Danth's Law • Argumentum ad lunam • Balance fallacy • Golden hammer • Loaded question • Escape to the future • Word magic • Spider-Man fallacy • Sanctioning the devil • Appeal to mystery • Informal fallacy • Common sense • Post-designation • Hyperbole • Relativist fallacy • Due diligence • Straw man • Good old days • Appeal to probability • Infinite regress • Circular reasoning • Media was wrong before • Is–ought problem • Ad iram • Just asking questions • Pink-baiting • Appeal to faith • Appeal to fear • Appeal to bias • Appeal to confidence • Appeal to consequences • Appeal to emotion • Appeal to flattery • Appeal to gravity • Appeal to hate • Argument from omniscience • Argument from silence • Argumentum ad baculum • Argumentum ad fastidium • Association fallacy • Broken window fallacy • Category mistake • Confounding factor • Counterfactual fallacy • Courtier's Reply • Damning with faint praise • Definitional fallacies • Equivocation • Fallacy of accent • Fallacy of accident • Fallacy of amphiboly • Gambler's fallacy • Imprecision fallacy • Moving the goalposts • Nirvana fallacy • Overprecision • Pathos gambit • Pragmatic fallacy • Quote mining • Argumentum ad sarcina inserta • Science doesn't know everything • Slothful induction • Spotlight fallacy • Style over substance • Toupee fallacy • Genuine but insignificant cause • Argument from incredulity • Appeal to age • Argumentum ad nauseam • Phantom distinction • Appeal to common sense • Argumentum ad hysteria • Omnipotence paradox • Argument from etymology • Appeal to trauma •
| Ad hoc: |  No True Scotsman • Moving the goalposts • Escape hatch • Handwave • Special pleading • Slothful induction • Nirvana fallacy • God of the gaps • PIDOOMA • Ad hoc • Tone argument •
| Arguments from ignorance: |  Science doesn't know everything • Argument from incredulity • Argument from silence • Toupee fallacy • Appeal to censorship • Science was wrong before • Holmesian fallacy • Argument from omniscience • Willful ignorance • Argument from ignorance •
| Causation fallacies: |  Post hoc, ergo propter hoc • Correlation does not imply causation • Wrong direction • Counterfactual fallacy • Regression fallacy • Gambler's fallacy • Denying the antecedent • Genuine but insignificant cause •
| Circular reasoning: |  Infinite regress • Argument by assertion • Argumentum ad dictionarium • Appeal to faith • Circular reasoning • Self-refuting idea •
| Emotional appeals: |  Appeal to fear • Appeal to emotion • Appeal to confidence • Deepity • Argumentum ad baculum • Appeal to shame • Appeal to flattery • Tone argument • Appeal to money • Argumentum ad fastidium • Appeal to gravity • Appeal to consequences • Loaded language • Style over substance • Appeal to pity • Appeal to hate • Pathos gambit •
| Fallacies of ambiguity: |  Fallacy of accent • Equivocation • Fallacy of amphiboly • Quote mining • Fallacy of ambiguity • Moral equivalence • Scope fallacy • Suppressed correlative • Not as bad as • Etymology • Continuum fallacy • Wronger than wrong • Definitional fallacies • Code word • Phantom distinction •
Formal fallacies: |  Confusion of the inverse • Denying the antecedent • Non sequitur • Affirmative conclusion from a negative premise • Not even wrong • Chewbacca Defense • Affirming a disjunct • Illicit process • Four-term fallacy • Negative conclusion from affirmative premises • Fallacy fallacy • Substituting explanation for premise • Enthymeme • Syllogism • Formal fallacy • Existential assumption • Masked man fallacy • Self-refuting idea • Argument by gibberish • One single proof • Affirming the consequent • False dilemma • Conjunction fallacy •
Fallacious arguments: |  Bumblebee argument • Fatwa envy • Gotcha argument • Hoyle's fallacy • Intuition pump • Logic and Creation • Not Circular Reasoning • Peanut butter argument • Great Beethoven fallacy • Fallacy of unique founding conditions • Evil is the absence of God • Argument from first cause • How do you know? Were you there? • Argument from design • Argument from beauty • Appeal to nature • Solferino fallacy • Religious scientists • Nothing to hide • Argument from fine tuning • Creep shaming • "I used to be an atheist" • Atheism as a religion • Argumentum ad populum • Argument from morality • Anti-environmentalism • Appeal to bias • Apophasis • Argumentum ad nauseam • Appeal to censorship • Argumentum ad sarcina inserta • Blaming the victim • Bait-and-switch • Danth's Law • Chewbacca Defense • Canard • DARVO • Demonization • Escape hatch • Friend argument • Everyone is racist • Gish Gallop • Greece-baiting • Gore's Law • Ham Hightail • Just asking questions • Leading question • Loaded language • Linking to authority • Loaded question • Lying by omission • Motte and bailey • Nazi analogies • Moving the goalposts • One single proof • Pink-baiting • One-way hash argument • Pathos gambit • Quote mining • Poisoning the well • Quidquid latine dictum sit, altum videtur • Race card • Red-baiting • Red herring • Release the data • Science was wrong before • Shill gambit • Straw man • Silent Majority • Uncertainty tactic • Style over substance • Terrorism-baiting • Weasel word • What's the harm (logical fallacy) • Whataboutism • Bullshit • Logical fallacy • Banana argument • Scapegoat • How come there are still monkeys? • Anti-racist is a code word for anti-white • Ontological argument • Omnipotence paradox • Presuppositionalism •
Conditional fallacies: |  What's the harm (logical fallacy) • Special pleading • Conditional fallacy • On the spot fallacy • Appeal to the minority • Argumentum ad populum • Galileo gambit • Professor of nothing •
| Genetic fallacies: |  Genetic fallacy •
|  | Appeals to authority: |  Ipse dixit • Appeal to confidence • Argumentum ad populum • Argument from authority • Linking to authority • Silent Majority • Invincible authority • Appeal to celebrity • Ultracrepidarianism • Appeal to the minority • Galileo gambit • Appeal to identity • Weasel word • Professor of nothing •
|  | Ad hominem: |  Ad iram • Argumentum ad cellarium • Bulverism • Poisoning the well • Blaming the victim • Tu quoque • Whataboutism • Nutpicking • Jonanism • Demonization • Shill gambit • Appeal to bias • Fallacy of opposition • Association fallacy • Damning with faint praise • Pathos gambit • Appeal to identity • Argumentum ad hominem • Nazi analogies • Not an argument • Nothing to hide • Scapegoat • 地下室论证 •
| Imprecision fallacies: |  Apex fallacy • Overprecision • Cherry picking • Overgeneralization • Texas sharpshooter fallacy • False analogy • Appeal to fiction • Spotlight fallacy • Pragmatic fallacy • Selection bias • Anecdotal evidence • Category mistake • Nutpicking • Imprecision fallacy • Confounding factor • Fallacy of accident • Neyman's bias •
Valid logical methods: |  Rapoport's Rules • Negative evidence • Reductio ad absurdum •
Fallacy collections: |  SeekFind • Nizkor Project • Fallacy Files • Your Logical Fallacy Is • Logically Fallacious •