Flaws in LSAT Logical Reasoning: False Dilemma

LSAT Prep

[Read Part 1 , Part 2 , Part 3 , and Part 4 of this series here.] 

Before we continue with Part Five of our examination of common flaws found in LR questions on the LSAT, let’s once again take a brief moment to review why it’s so important to understand these argumentative errors. Here’s how I began the first post in this series, where we looked at 
Source Arguments:

Considering the vast majority of LSAT Logical Reasoning questions will have an argument in their stimulus, and the vast majority of those arguments will contain some sort of flawed reasoning, I thought I would take a moment to address a variety of the flaws that tend to appear with some frequency. In a series of posts I’ll examine a number of common mistakes that authors on the test make, which should prove useful for both Flaw in the Reasoning questions (a type that accounts for about 15% of all LR questions), as well as other question types that require you to respond to argumentation.

With that in mind, let’s turn our attention to another type of mistake that LSAT authors make, and another one you have likely experienced yourself: False Dilemma. A False Dilemma argument assumes that only two possible courses of action (or two possible choices) are available, when in fact there may be others. In fact, we can actually consider the name itself as we explore the nature of this error: “False” obviously implies the inherent mistake in the reasoning given, and “Dilemma” arises from the idea of a choice between only two options. Typically this manifests itself as the author eliminating one of the possible courses of action, and thereby concluding that the other course becomes a certainty, despite the fact that more choices/options could be available.

Let’s consider an example of how a False Dilemma argument could be made:

“Because recent polling indicates that no voters in the county are strongly in favor of the proposed amendment, we can expect strong opposition to the amendment when it is voted on next month.”

Here we have evidence that no one finds the amendment to be extremely compelling, but does that necessarily mean that those same people are therefore strongly against it? Of course not, as it is entirely possible that some voters could be neutral towards the proposal, or even just mildly in favor of it.

Here’s how that particular error would likely be represented in an answer choice:

“fails to consider that some voters may be neither strong supporters nor strong opponents of the suggested amendment.”

So on test day be sure to keep an eye out for any argument that has a binary (two-option) feel to it, and consider whether other, alternative courses of action could potentially exist. If more than two possibilities do exist, then the author has presented a False Dilemma and you can quickly scan the answer choices for the one that reflects that mistake.

NOTE: Do not confuse a False Dilemma with a situation where the author legitimately establishes that only two possibilities exist! Phrases such as “Either A or B will occur, but not both,” imply a limited set of options/possibilities, and certain real-world scenarios inherently yield only two possibilities, like “you are either dead or alive,” or “you are either in the United States or you are not.” In these cases it is reasonable to conclude one thing when the other has been ruled out.

A final point about arguments of this type, and one that I have stressed previously: this is a very specific type of mistake and follows from a very consistent construction, so unless you see an argument where only two choices are presumed to be possible despite more existing, do NOT pick an answer like the one above. While this type of answer isn’t as commonly given as a trap as some of the other types we’ve seen, it does come up incorrectly at times as the test makers try to trick you. So be wary when you inevitably encounter them.

Keep an eye out for additional posts addressing a wide variety of other flaws you are likely to encounter on test day.