How to Tackle LSAT Questions on Flawed Logical Reasoning

LSAT test-takers often complain that the test is too abstract and impractical. Outside of the logic games section, no one will ever make you frantically diagram which of the campers Aaron, Betsy and Chloe will share a canoe with counselors Xavier, Yan or Zelda, if Chloe and Zelda never share a canoe except on Sundays and Betsy and Xavier paddle together on Thursdays, and so on.

However, one skill on the LSAT can actually come in handy in everyday life — a type of logical reasoning question called “flaw in the reasoning.”

Flaw questions present a poorly reasoned argument and ask test-takers to choose the answer choice that best describes the mistake in its reasoning. While the questions themselves involve made-up arguments and the answer choices vary in wording, the flaws in the reasoning are often common logical fallacies studied since antiquity.

[READ: How to Set an LSAT Study Plan Months in Advance.]

For example, consider the following argument: People who make crafts are crafty, and people who make noise are noisy, so the people who make LSAT tests must be testy. Therefore, like all testy people, the LSAT test-makers are jerks.

This fallacy is called “equivocation,” or ambiguity. Equivocal arguments confuse multiple, conflicting meanings of a term while logical arguments use terms consistently. This equivocal argument in the example slyly treats the words “testy” and “test” as similar, although their meanings are unrelated.

Answering Flaw Questions

Flaw questions would be easier if the answer choices just listed names of fallacies, like “equivocation” or “conditional reasoning error.”

Instead, they describe the flaw in the reasoning, which can be tricky to decipher. If the above argument appeared on the LSAT, the right answer choice might say that the writer uses one term in two different ways, or that the argument has an ambiguous term, or use another phrasing to mean the same thing. Thus, mastering flaw questions requires careful practice of both identifying flaws correctly and finding the answer choices that best describe them.

[Read: Study Habits That Won’t Help on the LSAT]

At first, the range of possible flaws can seem daunting, but most flaw questions relate to one of roughly a dozen frequent fallacies. To get started, here are six classic cases beyond equivocation.

Source Arguments

In everyday life, the credibility of a speaker matters. We don’t want advice from fools or judgments from hypocrites. In logic, however, arguments must be evaluated on their own merits, regardless of who makes them. On the LSAT, keep your eye out for critique of an argument based merely on the identity or past beliefs of the speaker.

Straw Man

A logical counterargument must be based on a fair and accurate portrayal of the argument in question. If a speaker on the LSAT oversimplifies, overgeneralizes or exaggerates an argument before critiquing it, look for an answer choice that describes mischaracterization.

Appeal to Authority

To make a logically sound appeal to authority, it must be the right authority. It is reasonable to trust a doctor’s diagnosis of your ailments and a mechanic’s diagnosis of your car troubles, but not vice versa. Furthermore, it is never logical to cite popular opinion, because crowds cannot be trusted to know what is true. Be wary of flaw questions in which a person’s inexpert opinion is cited as definitive proof.

[Read: How to Prepare for the LSAT on a Budget]


Look out for LSAT flaw questions that make a mountain out of a molehill, or a pattern out of a few instances. Any arguments in a flaw question that establish certain conclusions based on limited information or examples are suspect.

False Dilemma

Life is messy and rarely do decisions come down to only two options. If an argument in a flaw question rules out one option to settle conclusively on another, see if it fails to consider other obvious possibilities.

Internal Contradiction

If an argument is based on two premises that cannot both be true at the same time, then it cannot hold up. When a flaw question presents an argument that does not seem to add up, check if the premises are mutually inconsistent.

Recognizing these reasoning flaws can come in handy in making short work of shoddy arguments, from classroom discussions to political debates. Note, however, that when you point out other people’s flawed reasoning, you might find they get a bit … testy.

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