LSAT Flaw Questions: 5 Common Flaw Patterns

Flaw questions get easier when you stop treating them like trivia

A flaw question is not asking you to memorize a museum of formal fallacies. It is asking:

What is wrong with the move from the evidence to the conclusion?

If you can answer that in plain English before reading the choices, you are already ahead of most wrong answers. The test gets harder when you let the answer choices tell you what the flaw was supposed to be.

What a flaw answer must do

A correct flaw answer describes the author’s reasoning error.

It does not merely:

• restate a premise
• disagree with the conclusion
• introduce outside facts
• sound vaguely critical

It has to describe the actual bad move.

The fastest approach

1. Find the conclusion

Ask:

What is the author trying to get me to believe?

2. Find the support

What facts or observations are being used to get there?

3. Describe the gap in your own words

Before looking at the answers, say something simple:

• “They assumed correlation meant causation.”
• “They treated one example like proof about the whole group.”
• “They ruled out alternatives too quickly.”

That prediction does not need to sound official. It just needs to be directionally right.

Worked example

A nutrition blogger argues that because several of her friends felt more energetic after cutting out dairy, dairy is the main cause of low energy for most adults.

Conclusion:

• dairy is the main cause of low energy for most adults

Support:

• several friends felt more energetic after cutting out dairy

Likely flaw:

• the argument generalizes from a tiny and unrepresentative sample
• it also ignores other explanations for the energy change

Now imagine the answer choices trying to rename the problem for you.

Tempting wrong answer

“It fails to define what counts as low energy.”

That sounds analytical. But it is not the core problem. The core problem is the jump from a few anecdotes to a broad causal claim.

Better answer

“It draws a broad conclusion about most adults from a small number of personal cases.”

That is the actual bad move.

Common flaw patterns worth recognizing

Anecdote to general rule

One person, one company, one city, one study, one story. Then suddenly:

• all people
• all companies
• all cities
• the whole market

Correlation to causation

Two things move together, so the author assumes one caused the other.

No alternative explanations

The argument notices one possible cause and acts as if it were the only cause.

Necessary vs sufficient confusion

The argument mistakes:

• something required for the outcome

for:

• something that guarantees the outcome

Sampling flaw

The sample is biased, too small, or not representative, yet the conclusion gets treated as population-wide.

Relative vs absolute confusion

The author treats a percentage increase as proof of a large real-world effect when the base numbers may still be tiny.

Why flaw questions feel hard

They feel hard because the wrong answers are often written in abstract language.

Students think:

“I kind of understood the stimulus, but now the answer choices all sound like philosophy.”

That is normal.

The fix is to translate the stimulus into a blunt sentence before you enter answer-choice land.

Examples:

• “They acted like one success story proves the policy works.”
• “They assumed the only difference between the two groups was the thing they care about.”
• “They treated lack of evidence as evidence of absence.”

Plain-English predictions make abstract answer choices much easier to judge.

A second mini example

A city report notes that neighborhoods with more public trees have lower summer emergency-room visits for heat exhaustion. Therefore, planting more trees will by itself solve the city’s summer heat-health problem.

What is wrong?

The report shows a relationship, but the conclusion turns that into a single-cause solution.

Possible missing considerations:

• those neighborhoods may differ in shade, income, housing quality, or access to cooling centers
• planting more trees may help, but “will by itself solve” is much stronger than the evidence supports

If you can say that before reading the answers, the credited choice becomes much easier to spot.

The two most common mistakes on flaw questions

1. Picking an answer that is critical but not accurate

Some answers attack the argument from the side. They sound intelligent, but they do not describe the reasoning used.

2. Picking an answer that is too extreme

If the answer says the author “proves,” “completely ignores,” or “assumes without any evidence” when the argument is more moderate, slow down.

Precision wins these questions.

How to review flaw questions well

After a missed flaw question, write three lines:

1. The conclusion was:
2. The support was:
3. The author’s bad move was:

If line 3 is fuzzy, the review is incomplete.

The goal of flaw review is not just to know why the credited answer won. It is to name the broken reasoning move cleanly enough that you can recognize it faster next time.

A short drill plan that actually helps

If flaw questions are a weak point, do not just sprinkle them into mixed sets and hope.

Try this instead:

• do 8 flaw questions in a row
• prephrase the flaw every time before looking at the answers
• write one sentence after every miss saying what bad move the argument made
• repeat the same family two days later

That is how flaw questions stop feeling random.