In every case of political unrest in a certain country, the police have discovered that some unknown person or person...

zgnewquist on November 5, 2019

What is the flaw in this question?

It seems that the hidden assumption is that if it is an unknown person or group, then it is a single mastermind, however I don't know what flaw that relates too

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Irina on November 5, 2019


It sounds like a variation of the part -whole flaw/ error of composition. The argument tells us that because some unknown person is responsible for each of the cases of political unrest, a single person must be responsible for all of them. This is a flawed reasoning, we cannot infer that just because there is a "person" behind each unrest, it is always the same person. (C) has similarly flawed reasoning. Every citizen has a social security number, so it must be the same number for every citizen. Just because every member of the group has some characteristic, i.e. every unrest has a person associated with it, or every citizen has a SSN - we cannot infer that it is the same for every member of the group, i.e. same person, same number.

Let me know if this makes sense and if you have any other questions.

zgnewquist on November 6, 2019

Ok, thank you, that is helpful! Is there a way to tell when there is a much more simple flaw (as in this case) compared to other instances when the flaw is much more complicated? Thank you for your help.

Irina on November 6, 2019


I think most of the arguments on the LSAT involve fairly simple flaws. Sometimes the easiest way to identify a flaw is to focus on the logical structure of the argument and think about it in abstract terms, e.g. All X are Ys, or X v Y, if X then Y etc, instead of focusing on the substance. It is also helpful to do a set of flaw questions and see which flaws do you have most trouble identifying, and focus on practicing more of these types of flaws specifically.