In logic and argumentation, a slippery slope refers to a logical fallacy, meaning a flaw in reasoning that weakens an argument.
It happens when someone asserts that a certain proposition or action must be rejected because it would have unintended consequences, typically leading to a disastrous outcome. Essentially, they assume that a chain of events will occur without providing enough proof to support their view.
It is a type of informal fallacy, and, more specifically, it falls into the category of conditional fallacies.
In this article, we’ll explain in detail how this erroneous line of reasoning works, as well as show a variety of examples.
What Is the Slippery Slope Fallacy?
✍️ A slippery slope argument is committed when one argues, without providing adequate evidence, that a relatively insignificant event or course of action will lead to a chain of consequences, eventually resulting in some significant outcome.
The conclusion of the argument, or the culmination of the chain of events, is seen as unacceptable and therefore the first decision that would eventually lead to that outcome should be rejected.
Its logical form goes as follows:
- If A, then B.
- If B, then C.
- If C… then ultimately X.
👉 An example of a slippery slope would be:
“If we legalize marijuana, next people will want to legalize all the other drugs, which means the number of drug users and crime will explode, and this will lead to the end of the world as we know it!”.
It usually involves several different steps, as in the example above, but only two steps are actually required for the fallacy to occur.
Like many other logical fallacies, this one too, is known by a variety of different names. These names include:
- Absurd extrapolation
- The thin edge of the wedge argument
- The dam burst argument
- Pandora’s box argument
- The domino argument
- The snowball argument
- “If we let our government ban certain guns, they will eventually ban all guns.”
- “You should never be late. If you are late once for 5 minutes, next time you’ll be late for 15 minutes, and the next time for 1 hour, and eventually you won’t
show up at all.”
- “You must let me go to the party this weekend! If I don’t go, my friends will think I’m a complete loser and then they will dump me, and I will be forever alone!”
If voluntary euthanasia is legalized, then in the future there will be more cases of medical murder.
If we accept voluntary ID cards in the UK, we will end up with compulsory ID cards in the future.Corner, A., Hahn, U. and Oaksford, M., The Psychological Mechanism of the Slippery Slope Argument.
Why Is It a Fallacy?
The basis of a slippery slope argument is that a certain action will have unintended consequences, and each step along the “slope” will logically lead to the next one. However, the connections made by the arguer are seen as unwarranted because they don’t provide direct evidence for them.
As such, this fallacy can be often seen as a type of emotional appeal: Rather than relying on factual evidence, the arguer attempts to arouse fear in the listeners by showing that a particular decision may lead to some hypothetical, extreme consequences.