It's been two weeks since my last part in this series. The month of April was incredibly busy for me but now I'm back with a new installment in this series. Here are the links to the introduction to this series, to the Ad Hominem fallacy, to the Strawman fallacy, and to the Begging the Question fallacy.
A slippery slope argument is an argument that you start with one thing, and another, related thing will happen, and eventually it will snowball into something horrible. The reason that this type of argument can be fallacious is because it is often just a form of fear mongering. But like most fallacies, this type of argument is not always fallacious. What's important is whether or not you have warrant for the slippery slope.
An example of the slippery slope fallacy is one I am drawing from this linked website: If we ban Hummers because they are bad for the environment, eventually the government will ban all cars. So we should not ban Hummers.
Do you see how that argument is nothing more than fear mongering? There is absolutely no warrant for the fear that the government will ban all cars, especially since most cars are not as bad for the environment as Hummers. They're invoking fear of banning all cars because they don't want their Hummers to be banned from operation.
Here is an example of a pro-life argument that is not a fallacious slippery slope, though it is a slippery slope argument: Legalizing abortion will lead to legalizing other forms of killing, like killing infants or the seriously disabled. The reason that this is not fallacious is because there is warrant for it, especially regarding the philosophers who argue that the unborn are not persons due to lacking some property that, in their view, grounds personhood. It's simply following their logic to its natural conclusion. And we can see that this type of argument is warranted because there are, in fact, philosophers who are advocating infanticide and euthanizing the seriously disabled.
An example of a pro-choice slippery slope argument that is fallacious is that if pro-life people have their way, women will be back in the kitchen barefoot and pregnant. Many pro-choice people argue that taking away the legal right to an abortion will take us back into the dark ages where men are able to oppress women. This is clearly not a good argument and is merely fear mongering because they don't want their freedom to abort their unborn children taken away. But pro-life people do not want to oppress women, we just want our government to stop allowing the legalized slaughter of unborn human children.
So don't be fooled if someone tries to argue that your slippery slope argument is fallacious. Depending on what the argument is, if you can show that there is warrant for it then the argument is not fallacious.