Solving “Flaw” Questions

These passage-driven questions ask you to find the answer that describes a flaw in the given argument:

Which one of the following most accurately describes a flaw in the argument?
Which one of the following most accurately describes the reporter’s error in reasoning?
The argument above is most vulnerable to criticism on the grounds that it…
The reasoning in the argument is questionable because the argument…

If you see the word “EXCEPT” in a Flaw question, then the argument has several flaws. The wrong answers will each describe a problem with the argument. The correct answer will describe something that either doesn’t happen in the argument or isn’t a problem for the argument.

Make a Strong Prediction

Ideally, you’ll have already pinpointed at least one problem after carefully reading the argument. But if not, take a moment to find one. Here’s how:

Find the main conclusion. (If you have trouble, refresh your memory on argument parts and indicators.)
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‍Find the premises. Don’t assume that all the statements other than the main conclusion are premises. The passage might include an opposing viewpoint, some background information, or a concession.‍
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Figure out why the premises don’t prove the main conclusion. Even when you accept the premises as true, the flaw prevents the conclusion from being proven.

Focus on exactly what the argument is saying to avoid subconsciously helping it. Don’t make the very assumptions that the test writers are trying to hide.

Many arguments have more than one problem. After you spot one or two, those are your predictions. It’s time to read the answers.

Two Questions to Catch Wrong Answer Choices

Weed out incorrect answer choices by asking yourself these two questions:

Does this answer describe something that the argument actually does? If not, it’s not the correct answer. Move on. If it does match something in the argument, proceed to question
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Does this answer describe a problem for this particular argument?

Breaking Down Answer Choices

As a rule of thumb throughout the LSAT, if a sentence sounds wordy, long, or confusing, then break it into parts. The underlying idea is usually simple.

On Flaw questions, answer choices often sound abstract. When you read them part by part, ask yourself whether that part accurately describes something that happens in the argument. Consider this question and one possible answer:

The professor’s reasoning is flawed in that her argument…

(A) treats a condition that by itself is enough to make an action wrong as though it were necessary for that action being wrong.

In your mind, break this answer into two parts:

The argument takes a condition that by itself is enough to make an action wrong.
The argument treats that condition as necessary in order for the action to be wrong.

Restate part 1 in your own words. It says that there’s a sufficient condition in the lawyer’s argument for something being wrong. Ask yourself: “Does the passage contain a sufficient condition that makes an action wrong?” If not, move on to the next answer choice. But if so, keep reading, because it could be the right answer.

Part 2, in simple terms, says that the argument takes part 1 to be necessary.

Since the question assumes that “the reasoning in the lawyer’s argument is flawed,” the author is saying that the lawyer is treating a condition as though it’s necessary when it’s actually sufficient. Ask yourself: “Does the lawyer in the passage treat the sufficient condition from part 1 as if it were necessary?” If so, keep reading this answer choice.

You’ve established that the answer choice is describing something that the lawyer actually does. Next, ask yourself:

Is this a problem? If I fixed this flaw, would it significantly help the lawyer’s argument? If so, this is probably the correct answer choice.

The correct answer will accurately describe something that’s happening and will be a flaw or problem with the argument. If the answer is “no” to any of the questions above, you can stop and move on—that answer is wrong.

The Two Most Common Flaws on Logical Reasoning

Confusing sufficient with necessary
Confusing correlation for causation

Watch Ben discuss these flaws in more depth here.

Test Your Understanding!

Match the following arguments to the criticisms to which they’re most vulnerable. These are examples of some of the most common flaws that appear on the LSAT.

Arguments:

“Every word in the Bible is true because it says so in the Bible.”
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“A study rewarded certain kindergarteners for their good behavior with 10 minutes extra playtime at recess. Some teachers objected, feeling that schools have a moral obligation to give students as much educational time as possible while they are at school. Still, at the end of the school year, the results of the study showed that the children selected for the extra playtime far outperformed the other students in their ability to read. Therefore, if we want to enhance our students’ ability to read, we should reward them with extra playtime.”
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“Herbert is a nutjob who routinely mixes up his lefts and rights. Therefore his tax plan is bad for the country.”
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“Today I splurged and bought a dozen expensive ingredients for a gourmet recipe I have long been planning to make. For every single ingredient in the dish, I bought the finest gourmet product available. Therefore when I prepare this recipe tonight using these ingredients, it is sure to be a gourmet dish.”
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“Evolutionists think that a fish was swimming along and one day a leg popped out the side, and another leg popped out the other side, and the fish started walking along the beach. This could never have happened, therefore the theory of evolution is wrong.”
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“Being run over at a football game tailgate party by a U-Haul full of kegs of beer will kill you. John died this weekend, therefore John must have gotten run over by a U-Haul full of kegs of beer.”
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“Last night I went out to dinner at a fine restaurant. I had the most expensive dish on the menu. It was delicious. The restaurant was so expensive that I spent my week’s paycheck on the meal. It is clear to me that each ingredient of the dish must have been extremely expensive to procure.”
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“People with dogs spend a lot of time walking. Therefore a propensity to walk causes one to own a dog.”

Criticisms:

A) Infers, from the fact that a certain condition is necessary for another condition to exist, that the first condition must be sufficient to prove that the second condition exists.

B) Infers causation, where only correlation has been shown.

C) Assumes what it purports to show is true.

D) Assumes that if all parts of a whole have a certain characteristic, then the whole must have that same characteristic.

E) Assumes that if a whole has a certain characteristic, then each part of the whole must have that same characteristic.

F) Criticizes the proponent of a policy rather than the policy itself.

G) Proposes a distorted version of an opposing viewpoint, in order to more easily attack that viewpoint.

H) Relies on a sample there is reason to believe is biased.

Answers