Career Files, Pre-Law

Logical Reasoning: Flaw Question

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Logical Reasoning questions comprise roughly half the LSAT, so there have been thousands upon thousands of them in the history of the test. While it might seem as if each one is as individual as a Justin Bieber haircut, the truth is that there are consistent patterns that underlie them. By recognizing these patterns, you’ll increase your pacing and accuracy on the LSAT.

The question below is what we at Blueprint LSAT term a flaw question, which asks you to identify the problem in the argument. Flaw questions are exceedingly common on the LSAT. Less common than a tween at a Biebs concert, but common.

The Question:

Joaquin’s family doesn’t understand why he is pursuing a doctorate degree in mathematics. But a doctorate in mathematics is an absolute requirement if one wants to become a professor in mathematics. We can only conclude that Joaquin must hope to someday become a professor of mathematics.

The argument is most vulnerable to criticism on the grounds that it

(A) ignores the possibility that a doctorate in mathematics might not be the only requirement to become a professor of mathematics
(B) presupposes without justification that no one else Joaquin knows is pursuing a doctorate in mathematics
(C) overlooks other reasons Joaquin might have for pursuing a doctorate in mathematics
(D) fails to explain why Joaquin would want to become a professor in mathematics
(E) assumes that becoming a professor of mathematics is a good choice of career

The Analysis:

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Joaquin’s family wonders why he would want to devote years of his life to work that’s really hard stuff that almost no one understands. The argument tries to provide insight: a doctorate in math is necessary to become a math professor. The problem with this argument is that there are other reasons a person could pursue a PhD. Joaquin could, for example, be after some big-shot analyst job on Wall Street. Alternatively, he could think that a Ph.D. in math might bring in the ladies. He would be wrong, but he might think it.

(C) is the correct answer because it points out that the argument overlooks other reasons Joaquin might have for obtaining a Ph.D. This argument takes a necessary condition (a doctorate in math is necessary to become a professor) and acts as if it were sufficient to conclude that Joaquin wants to become a professor. Whenever an argument acts as if a necessary condition is sufficient or vice versa, it’s a flawed argument.

The Incorrect Choices:

Choice (A) could be true; there could be other requirements to become a professor. But this isn’t relevant to our conclusion about Joaquin and what he wants to do. For all we know he could have met all of the other requirements.

Answer choice (B) discusses other people. However, the argument is only about Joaquin and his family so bringing in another person doesn’t describe the flaw in the argument.

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Answer choice (D) deals with Joaquin’s motivations. While it would seem that his family doesn’t understand Joaquin’s goals, it doesn’t matter whether there’s good reason or not to become a professor; it only matters whether pursuing the PhD is good evidence that he’s trying to become a professor.

The argument doesn’t conclude anything about whether Joaquin is making the right decisions in his life, and that’s a big problem for choice (E). Becoming a professor could be a great decision or it could be a huge mistake. Either way, the conclusion is unaffected.

In the End:

In the same way the LSAT asks the same questions repeatedly on the LSAT, so too does the LSAT use the same types of flawed logic again and again. If you want to master the LSAT, it’s critical that you learn the various ways logic can go wrong. In this case, the flaw is listening to a Justin Bieber song confusing a sufficient condition with a necessary one. Once you’re familiar with this flaw, you’ll tackle similar questions much more quickly and easily.

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