The Last Straw Fallacy: Another Causal Fallacy and Its Harmful Effects

by Carolyn Cusick & Mark Peter
November 2015
Argumentation; Nov. 2015, Vol. 29 Issue 4, p. 457

“We have noticed a pattern of arguments that exhibit a type of irrationality or a particular informal logical fallacy that is not fully captured by any existing fallacy. This fallacy can be explored through three examples where one misattributes a cause by focusing on a smaller portion of a larger set-specifically, the last or least known-and claiming that that cause holds a unique priority over other contributing factors for the occurrence of an event. We propose to call this fallacy the ‘last straw fallacy’ and will argue why these examples actually warrant a new logical name. Finally, we will show how these cases point to a deeper insight about the contexts in which we typically invoke this type of reasoning and some significant harmful consequences of doing so.”

Source: The Last Straw Fallacy: Another Causal Fallacy and Its Harmful Effects

Brilliant! I’ve been looking for a name for this particular (and incredibly common) mistake in reasoning, and thanks to the interwebz I finally found it! It’s very important to analysis because as obvious as the mistake is, it’s so widespread it’s become part of the general discourse. When people talk about a group that “tips” an election, for example, that’s the mistake they’re making. The most relevant group in deciding an election is, of course, the majority group. Or, if you want to use the camel example, look at the chart below and tell me what was the number one contributor to the breaking of the camel’s back. Not the straw. In fact, everything else is more important than the straw.