One thing leads to another
I hate the slippery slope fallacy. It is greatly overused and can be effective even though it is an informal logical fallacy. Many times I find myself itching to advance a slippery slope argument and it is difficult to stop myself. Recently I was discussing this issue online when a commenter that obviously went to a better school than I did said, “My law school professor said that a slippery slope argument is the type of argument one uses to divert attention while thinking of a legitimate argument”. I think that is spot on and remembering that piece of wisdom helps me to avoid using the slippery slope (for the most part–sometimes I have nothing else).
One source of consternation for me regarding the slippery slope is how the definition of the argument has changed over time. A slippery slope argument states that a relatively small first step leads to a chain of related events culminating in some significant effect, much like an object given a small push over the edge of a slope sliding all the way to the bottom. Traditionally, there had to be some sort of causal effect between the first step and the subsequent events. In modern usage, there does not need to be a causal effect. The first step and the subsequent events just have to be related somehow. Let’s look at an example of modern usage using some statements from perhaps the dumbest person ever to be a member of the United States House of Representatives, Louie Gohmert, on restricting ammunition capacities and same-sex marriage/polygamy/bestiality:
In fact, I had this discussion with some wonderful, caring Democrats earlier this week on the issue of, well, they said “surely you could agree to limit the number of rounds in a magazine, couldn’t you? How would that be problematic?”
And I pointed out, well, once you make it ten, then why would you draw the line at ten? What’s wrong with nine? Or eleven? And the problem is once you draw that limit; it’s kind of like marriage when you say it’s not a man and a woman any more, then why not have three men and one woman, or four women and one man, or why not somebody has a love for an animal?
There is no clear place to draw the line once you eliminate the traditional marriage and it’s the same once you start putting limits on what guns can be used, then it’s just really easy to have laws that make them all illegal.
Let’s unpack this statement to get at the fallacy. He almost gets to the fallacy on ammunition capacity but pivots to a popular argument on same-sex marriage to demonstrate a slippery slope. His argument is that allowing same-sex marriage will “make it easy” to allow bestiality and bigamy. He doesn’t demonstrate how this would happen, however. There is no causal connection between allowing same-sex marriage and bestiality/polygamy. These issues are just related in his mind. The slippery slope glosses over the fact that the justifications for allowing same-sex marriage are completely different from the justifications of allowing bestiality/polygamy. It also completely avoids the fact that there is very little support for bestiality/polygamy compared to SSM. In Gohmert’s world, a proponent for bestiality/polygamy would only have to argue, “But but we allow same-sex marriage, why not polygamy/bestiality????!” Do you really believe that the proponent’s argument would carry the day? We criminalize both polygamy and bestiality. We do not criminalize (with some exceptions) homosexual behavior. We treat these issues differentially. By using the fallacy, Gohmert gets to appeal to nihilism by changing the debate framing from same-sex marriage to the other two categories that are completely different. The merits of the arguments about SSM become immaterial. An SSM supporter would ostensibly have to support polygamy and bestiality in Gohmert’s world. That is ridiculous. Each of these issues should be taken individually.
So, what would be a proper use of the slippery slope? An argument where one can demonstrate the causality between the discreet steps. A leads to B which leads to C and so on to the end point of X. Gohmert’s example is that A leads to X but he doesn’t demonstrate how each step will do it (because he knows it won’t but wants to pivot to something that would scare people). The intervening events between A to X have to be factually based, not just alleged.
Keep an eye out for someone who uses the slippery slope in a fallacious manner. They’re deliberately and in bad faith misleading the argument. Ask them how the initial step leads to the end result. Make them get granular on exactly how the chain of events works. You’ll see that they have to make some sort of assumption or leap to tie it together.