slippery slope (logical fallacy)

Glossary of Grammatical and Rhetorical Terms

slippery slope
"Slippery slopes are so tricky to negotiate that even the first timid step upon them sets you sliding all the way to the bottom. . . . The fallacy is that of supposing that a single step in a particular direction must inevitably and irresistibly lead to the whole distance" (Madsen PIne, How to Win Every Argument, 2015). (Blaine Franger/Getty Images)


In informal logic, slippery slope is a fallacy in which a course of action is objected to on the grounds that once taken it will lead to additional actions until some undesirable consequence results. Also known as the slippery slope argument and the domino fallacy.

The slippery slope is a fallacy, says Jacob E. Van Fleet, "precisely because we can never know if a whole series of events and/or a certain result is determined to follow one event or action in particular.

Usually, but not always, the slippery slope argument is used as a fear tactic" (Informal Logical Fallacies, 2011).

See Examples and Observations below. Also see:

Examples and Observations

  • "To judge from the news stories, the entire nation is coming to resemble San Francisco after a heavy rainfall. In the press, the phrase 'slippery slope' is more than seven times as common as it was twenty years ago. It's a convenient way of warning of the dire effects of some course of action without actually having to criticize the action itself, which is what makes it a favorite ploy of hypocrites: 'Not that there's anything wrong with A, mind you, but A will lead to B and then C, and before you know it we'll be up to our armpits in Z.'"
    (Geoff Nunberg, commentary on "Fresh Air," National Public Radio, July 1, 2003)
  • "The slippery slope fallacy is committed only when we accept without further justification or argument that once the first step is taken, the others are going to follow, or that whatever would justify the first step would in fact justify the rest. Note, also, that what some see as the undesirable consequence lurking at the bottom of the slope others may regard as very desirable indeed."
    (Howard Kahane and Nancy Cavender, Logic and Contemporary Rhetoric, 8th ed., Wadsworth, 1998)
  • The Slippery Slope of Voluntary Euthanasia
    "If voluntary euthanasia were to be legalised it would prove impossible to avoid the legislation, or, at least, toleration, of non-voluntary euthanasia. But, even if the former can be justified, the latter clearly cannot. Hence, it is better that the first step (legalising voluntary euthanasia) not be taken so as to prevent a slide into non-volunteer euthanasia."
    (John Keown, quoted by Robert Young in Medically Assisted Death. Cambridge University Press, 2007)

  • The Slippery Slope of Public Murals
    "I hope the art mural at 34th and Habersham will not be allowed. You open the gate for one, you open it for all and you'll have it all over the city. A person wanting to paint on buildings is nothing more than upscale graffiti. More than likely it will go too far."
    (anonymous, "Vox Populi." Savannah Morning News, September 22, 2011)
  • "All Politics Takes Place on a Slippery Slope"
    "Logicians call the slippery slope a classic logical fallacy. There’s no reason to reject doing one thing, they say, just because it might open the door for some undesirable extremes; permitting “A” does not suspend our ability to say 'but not B' or 'certainly not Z' down the line. Indeed, given the endless parade of imagined horribles one could conjure up for any policy decision, the slippery slope can easily become an argument for doing nothing at all. Yet act we do; as George Will once noted, 'All politics takes place on a slippery slope.'

    "That’s never been more true, it seems, than now. Allowing gay marriage puts us on the slippery slope to polygamy and bestiality, opponents say; gun registration would start us sliding into the unconstitutional morass of universal arms confiscation. An NSA whistle-blower, William Binney, said last week that the agency’s surveillance activities put us on 'a slippery slope toward a totalitarian state' . . .. And this week we’re hearing a similar argument that President Obama’s decision to arm Syrian rebels, however meagerly, has all but doomed us to an Iraq-style debacle . . .. These critics may be right to urge caution, but in their panicked vehemence, they’ve abandoned nuance and succumbed to summoning up worst-case scenarios. UCLA law professor Eugene Volokh points out that metaphors like the slippery slope 'often start by enriching our vision and end by clouding it.' Decriminalizing marijuana doesn’t have to turn the U.S. into a stoner nation, nor does sending M-16s to Syrian rebels inevitably mean boots on the ground in Damascus. But that’s not to say we shouldn’t watch our footing."
    (James Graff, "The Week." The Week, June 28, 2013)
  • The Slippery Slope of Immigration Reform
    "In a well-meaning effort to curb the employment of illegal aliens, and with the hearty good wishes of editorialists who ordinarily pride themselves on guarding against the intrusion of government into the private lives of individual Americans, Congress is about to take this generation's longest step toward totalitarianism.

    "'There is no "slippery slope" toward loss of liberties,' insists Senator Alan Simpson of Wyoming, author of the latest immigration bill, 'only a long staircase where each step downward must be first tolerated by the American people and their leaders.'

    "The first step downward on the Simpson staircase to Big-Brotherdom is the requirement that within three years the federal government come up with a 'secure system to determine employment eligibility in the United States.'

    "Despite denials, that means a national identity card. Nobody who is pushing this bill admits that--on the contrary, all sorts of 'safeguards' and rhetorical warnings about not having to carry an identity card on one's person at all times are festooned on the bill. Much is made of the use of passports, Social Security cards and driver's licenses as 'preferred' forms of identification, but anyone who takes the trouble to read this legislation can see that the disclaimers are intended to help the medicine go down. . . .

    "Once the down staircase is set in place, the temptation to take each next step will be irresistible."
    (William Safire, "The Computer Tattoo." The New York Times, Sep. 9, 1982)
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    Nordquist, Richard. "slippery slope (logical fallacy)." ThoughtCo, Mar. 3, 2017, Nordquist, Richard. (2017, March 3). slippery slope (logical fallacy). Retrieved from Nordquist, Richard. "slippery slope (logical fallacy)." ThoughtCo. (accessed January 18, 2018).