Logical fallacy #2: The slippery slope

Definition: The arguer claims that a sort of chain reaction, usually ending in some dire consequence, will take place, but there’s really not enough evidence for that assumption. The arguer asserts that if we take even one step onto the “slippery slope,” we will end up sliding all the way to the bottom; he or she assumes we can’t stop partway down the hill. 

This is the typical definition of a slippery slope--that a particular event will start a chain of consequences leading to an undesirable result. A student asked if the slippery slope could lead to an imagined positive outcome. For example, I might get a good grade in one of my law classes and then imagine that I will graduate summa cum laude and get the best score on the bar exam and then become a famous attorney. I don't see why this type of thinking couldn't also be a slippery slope, because the positive consequences I imagine of my one good grade are also completely without evidence!

Tip: Check your argument for chains of consequences, where you say “if A, then B, and if B, then C,” and so forth. Make sure these chains are reasonable.

 

(Credit: Parts of the definition above, and the tip, are courtesy of the Writing Center, University of North Carolina at Chapel Hill.)

Here are a couple of examples, courtesy of a student in my other class: