Flawed Reasoning in LSAT Logical Reasoning Questions: Source Arguments

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    LSAT logical reasoning, LSAT prep, PowerScore LSAT prep, LSAT prep helpConsidering 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.

    A common mistake found in a number of Flaw in the Reasoning questions is one that should be familiar to most test takers from their daily experiences: Source Argument. Also known as an ad hominem attack (meaning “to the person”), a Source Argument commits a singular, consistent mistake by attacking the person/group making a claim (the source), as opposed to attacking the details of the claim itself. The LSAT is concerned solely with argument forms and their validity, so by failing to address the argument and instead focusing on the character or motives of the argument’s source, an author does nothing to undermine an opponent’s position. 

    I say that most test takers should already be familiar with this flawed strategy of arguing because it is an often-favored style of rebuttal for a lot of people in daily life (particularly children and, sadly, politicians; I’ll leave it to you to consider the extent of similarity between those two groups). Consider an example:

    “Mayor Jones’ anti-DUI campaign should not be taken seriously. After all, the mayor himself was cited for driving under the influence in college.”

    Has the statement that the mayor once committed the crime he is seeking to prevent really shown that his campaign should be ignored? Of course not. The merits of the campaign are left unchallenged by an attack on the person himself, so this argument against the mayor is a poor (flawed) one.

    Typically source arguments will be easy to spot on the LSAT, as they almost always take one of two identifiable forms:

    1. Focusing on the actions of the source (as in the example above).
    2. Focusing on the motives of the source.
    So when you encounter a stimulus where the author is attempting to disprove someone’s position by attacking the person or group behind that position, and you are then asked to describe the author’s error, what can you expect of the correct answer choice? Well it will contain a few predictable points: (1) it will note that the author is attempting to discredit/criticize a position or claim, and (2) it will state that the author is in error for focusing on the proponent/source of that claim. Here are a few examples of source arguments as described by the test makers:

    “it is directed against the proponent of a claim rather than against the claim itself”

    “it draws conclusions about the merit of a position and about the content of that position from evidence about the position’s source”

    “assuming that a claim is false on the grounds that the person defending it is of questionable character”

    Always be on the lookout for arguments that address the nature of a claim’s source instead of the contents of the claim itself, and when asked to describe that flaw you should be able to quickly choose the answer with the characteristics given above.

    Keep an eye out for additional posts addressing a wide variety of other flaws you are likely to encounter on test day. Commit them all to memory and you’ll find yourself well prepared to respond to nearly any argument you come across.