Based on the idea that an object placed at the top of a slippery slope will slide all the way to the bottom if given even a small nudge, the Slippery Slope Fallacy means arguing that even a small step taken in one direction will lead to some drastic consequence. This argument usually ignores the individual connections between events in favor of simply linking one event inevitably to another. However, this is not inherently fallacious ... after all, some slopes really are that slippery. It does, however, fall on the claimant to justify a logical, probable, and inevitable series of events. Without that, the argument has no meaning.
Note that this can approach a YMMV. A Slippery Slope argument that you agree with will seem more reasonable than one you disagree with.
There is also a "Reverse Slippery Slope Fallacy", namely the argument that since one has taken the first step down the slope without sliding to the bottom, it is clearly safe to take the next step. (Demonstration: smoking one cigarette won't get you hooked, or give you cancer. Nor will smoking a second cigarette. However, keep smoking cigarettes, and bad outcomes become increasingly likely.)
Another related trope is Jumping Off the Slippery Slope, where a character quickly goes from doing something morally ambiguous to becoming clearly evil.
- DirectTV has a series of advertisements that show a chain of events beginning with getting Cable instead of DirectTV and ending in something bad happening. While it does show a (somewhat) logical progression from each event to the next, none of the events described are either inevitable nor necessarily relevant to the viewer. (For example, having a bad day because of your cable company could result in the wrong guy getting convicted and coming after you for revenge, but only if you happened to be a defense attorney.) Of course, the fact this fallacy is used is the joke.
- Don't Copy That Floppy: Disk Protector uses it:
You say, "I'll just make a copy, for me and a friend"
Then he'll make one and she'll make one and where will it end?
One leads to another, then ten, then more
- Lincoln: During the debate over passage of the Thirteenth Amendment, which would outlaw slavery in America, Representative Yeaman announces his opposition to the amendment, despite hating slavery, because he fears it would lead to further reform, such as letting all black people vote. Just before the vote on the amendment, Lincoln urges him to focus on the singular issue of slavery and let the rest be debated about in its own time.
Yeaman: What shall follow upon that? Universal enfranchisement? Votes for women?
- Animal House uses this argument in the scene where Otter convinces Dean Wormer that it is unethical to target the entire fraternity for the action of "a few sick and twisted individuals". He then claims that if they are going to blame his fraternity, then they should blame the entire fraternity system, and if they are going to blame the entire fraternity system, they should blame all of American society in general. They then leave the room humming the national anthem.
- Crazy Ex-Girlfriend: To rally a group of tenants to file a class action lawsuit against their landlord, Rebecca convinces them that the lack of hot water in their apartments will result in all their children becoming crack addicts.
- Real Time with Bill Maher: Bill Maher rebutted this type of fallacious reasoning in one routine: "Gay marriage will not lead to dog marriage! When we gave women the vote we did not also have to give it to parakeets. When we freed the slaves we were not obligated to free the gerbils."
- Troper's Law is a reaction to a slippery slope argument commonly found on this very wiki. "If we do anything at all in a way similar to the way that Wikipedia does it, we will become as restrictive and bureaucratic as Wikipedia is perceived." Of course, this does not address concerns that the site is becoming more restrictive and bureaucratic, only that it does not inevitably follow that any action in that direction will lead to a worst-case scenario.
- In "Don't Download This Song", "Weird Al" Yankovic says that if you download music (his own song being freely available on the Internet), you will become a hard case, robbing liquor stores and driving over people in your car.
- Discussed in Chapter 6 of Strong Female Protagonist. Ex-superhero Allison, after using her Super Strength to force an unwilling person into healing a friend, fears that compromising her ideals for the greater good has put her one step farther down the slippery slope to becoming a supervillain. Her philosophy professor, Gurwara, responds that she may be over-fearing it, and thereby blinding herself to previous times that she crossed a line. In his view, the real danger of the slippery slope fallacy is not the slippery slope itself, but its implicit claim to a person that they are at the top of the slope and have not already compromised.
- Parodied in Saturday Morning Breakfast Cereal: "Commentary", where it's treated like a thought experiment in physics: "Imagine an idea placed at the top of a frictionless slope. Assume infinitely powerful gravity." (Even though this is purely metaphorical, it's stated in such strong metaphorical terms that it's also Exaggerated Trope.)
- In the King of the Hill episode "Trans-Fascism", Hank has to struggle between the law and his morals when he and his pals start running a lunch truck that sold foodstuffs banned by the city council. He knows Arlen is enacting an unfair law that even the person who had suggested it in the first place now regrets, but knew he could well cause worse problems. In a Dream Sequence wherein George Washington, Abraham Lincoln, and Tom Landry (who all faced Slippery Slope crises on a much bigger scale) confront him, Washington quotes the trope directly.
- Used by Miss Finster in the Recess episode "The Great Jungle Gym Standoff" to argue why they shouldn't give in to the kids' demands.
Miss Grotke: Maybe the kids have a point. Maybe we should give them what they want. It's just a jungle gym.
Miss Finster: Just a jungle gym? I always knew you were a troublemaker, Grotke. Give in to the jungle gym today and they'll want better food tomorrow. Soon they'll demand a longer recess and then more free reading time. Eventually, society will crumble and western civilization as we know it will come to an end!
- A number of pro-gun people in the U.S. debate over gun control seem to think that any form of restriction whatsoever will lead to the government confiscating all firearms.
- Dropping the atomic bombs on Japan. Many of the scientists were certain that using it would lead to an arms race and total destruction of civilization. We've done a pretty good job avoiding the second bit (albeit with a few close calls, some of which were far closer than people knew at the time), but they got the arms race bit right.
- Used frequently by politicians. Especially shows up around election time where voting for an opponent will usually be portrayed as resulting in a dystopia of some sort, usually authoritarian in nature.
- Pops up a lot in the pro-choice/pro-life debate. Pro-choice people might say any restrictions on abortion will inevitably result in a theocratic Christian fundamentalist dystopia right out of The Handmaid's Tale where women are used as breeding cattle ... even though this didn't happen in any of the Western democracies during the many decades when abortion was illegal. Pro-life people, meanwhile, will proclaim that the legalization of abortion necessarily opens the door to eugenics, euthanasia, Social Darwinism, and so forth, also ignoring the fact that these things happened before elective abortion was legal.
- Quite frequently Played for Laughs, in which case the logical leaps necessary to get from root cause to end result will be intentionally amplified and exaggerated.
- Musical comedian Rob Paravonian had some fun with this in "Pushing Band Candy," his tale of how he built an empire out of selling candy bars for school band fundraisers. And really, once he went too far pushing the product and got himself expelled, what else could he become but a hardcore drug dealer?
- Parents often claim that lying will lead to becoming a criminal.
- This is generally accepted as one of the three prohibited taboos of academic debate (British Parliamentary Style at least), the others being the related Armageddon, and any mention of Hitler or the Nazis.
- Atheism makes you a Straw Nihilist Omnicidal Maniac. This need not always be the case, however.
- Young Earth Creationists frequently use this for arguing that accepting evolution and that the Earth is millions of years old will lead you to question the rest of The Bible and lead you to atheism. Surprisingly, Richard Dawkins agrees with them in this sense.
- An inversion of sorts comes from the promoters of Atheism Plus like P.Z. Myers, who are baffled that many existing atheists who came to their lack of belief through rationality do not support the same social justice issues he does, like feminism, to which he says "Why bother being an atheist?" Never mind that they may have different social and political opinions, there being no necessary connection between them. Partly this is Creator Provincialism, as atheists in the United States do tend to be left-wing. Countries with greater numbers of atheists have more even distribution on the political spectrum.
- Used often in the U.S. minimum wage strikes. Pundits frequently asked if the minimum wage was going to be raised by a few dollars per hour now, what was to stop it growing to absurd levels. This led to many parodies on The Daily Show with Jon Stewart, especially when one anchor asked "Why not raise minimum wage to one hundred thousand dollars an hour?" Apparently there is no middle ground between less than three hundred dollars a week and four million.
- Often used to argue against laws banning hate speech. Free speech absolutists argue that if you deny free speech rights to Neo-Nazis, you must deny them to everyone. Legal precedents and constitutional provisions, however, can sometimes make this true.
- This can extend to companies flexing their muscles to remove someone who uses such fiery rhetoric. Of note is Alex Jones, whose Info Wars had been removed from various companies platforms through 2018. There were quite a few people who express worry that if someone like Pay Pal or YouTube could toss Alex Jones from their platforms, there are no practical barriers to stopping them from possibly outright tossing someone else out for being a Democrat or a Republican.
- Some take the argument even further, and claim that outright abuse and harassment should be protected by freedom of speech, and people who have been dropped from YouTube or social media platforms for their horrific behavior tend to brand the bans as media companies "censoring" them for their views.
- Frequently used in discussions regarding whether or not same-sex marriage should be legalized. Those opposed argue that allowing same-sex couples to marry will lead to similar laws allowing people to marry animals or underaged children. Somehow the opposite (limiting marriage leads to a world where eventually nobody is allowed to marry anyone) is never addressed.
Looks like this fallacy but is not:
- If one does establish the chain of logical implications (or quantify the relevant probabilities).
- If it establishes that the progression is inevitable.
- The phrases "Where does it stop?" and "Where do you draw the line?" aren't always this fallacy. While they can be, if used to imply that there is no "line" or "stop," it can also be a legitimate question when it's ambiguous what a person or group's goals/standards are.
- In some cases of legal precedent; Eugene Volokh has written a paper about the slippery slope that analyzes examples where it can be valid.
Problems with pointing out the fallacy
- Just because sliding down the slope is not inevitable, does not make it impossible. Sliding down the slope may even be likely.
- Warning of the slippery slope can imply that one's position is currently at the top of the slope and has not already compromised.