Flaw questions are the single most common Logical Reasoning question type, on most modern LSATs you'll see somewhere between six and nine of them across your two scored LR sections. That makes them the highest-leverage type to master: a student who converts flaw questions from a weakness into a strength typically moves their LR performance more than with any other single change.
The task is precise: the argument in the stimulus is broken, and your job is to name how it's broken. Not whether it's broken, it always is, and not what would fix it. The correct answer describes the gap between the evidence given and the conclusion drawn, in abstract language that matches this argument exactly.
The good news is that the test recycles a small set of flaw patterns over and over: correlation treated as causation, necessary conditions confused with sufficient ones, sampling problems, attacking the person instead of the argument, circular reasoning, false dilemmas, and a handful of others. Learn to recognize the pattern in the wild and the answer choices stop feeling like five plausible paraphrases.
Stem language that signals this type:
Before touching the answers, state the argument's conclusion in your own words and identify what's offered to support it. The flaw always lives in the jump between the two, if you can say "the evidence shows X, but the conclusion claims Y," you've usually already found it.
Say the error simply, "they assumed the only cause is the one they mentioned" or "they treated a requirement as a guarantee." A plain-English prediction protects you from answer choices dressed in intimidating abstract language.
Flaw answers are written generically: "takes a condition necessary for an outcome to be sufficient for it." Force each answer to point at actual words in the stimulus. If you can't attach the description to specific sentences, it doesn't describe this argument.
Many flaw answers make two claims at once, the argument "presumes X without providing justification." The answer is only right if the argument really does presume X. A description of something the argument never did is wrong no matter how flawed it sounds.
An original question written in the LSAT style, not from a real test.
Restaurant critic: The new bistro on Oak Street must have hired away the head chef from Marigold, the acclaimed restaurant across town. After all, the bistro's tasting menu features a saffron custard nearly identical to the one that made Marigold famous, and no other restaurant in the city has ever served that dish.
The reasoning in the critic's argument is flawed because the argument
Pick an answer to check your reasoning.
The most dangerous wrong answer accurately describes something in the argument that isn't the error. Yes, the author cited an expert, but citing an expert wasn't what broke the reasoning. Match the answer to the gap, not just to the text.
Choices frequently name classic flaws, ad hominem, circularity, equivocation, that simply don't appear in this stimulus. Familiar-sounding is not the same as present.
Watch for "presumes that X is the only…" or "takes for granted that all…", the answer is only correct if the argument's logic actually needs that extreme a claim.
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Typically six to nine across the two scored Logical Reasoning sections, usually the most of any single question type, which is why flaw pattern fluency is one of the highest-return LSAT skills.
Causal flaws (correlation treated as causation), conditional-logic errors (confusing necessary and sufficient conditions), unrepresentative samples, part-to-whole errors, ad hominem attacks, circular reasoning, equivocation, and false dilemmas cover the large majority of flaw questions.
Usually the abstraction step: you see the error, but the answer choices describe it in generic conditional or causal language you haven't practiced translating. Drill matching plain-English errors to their formal descriptions and accuracy jumps quickly.
You need working fluency with necessary versus sufficient conditions and contrapositives, a meaningful share of flaw answers are written in that vocabulary. You don't need symbolic-logic notation beyond that.
Find the unstated premise the argument can't live without.
Pick the new fact that damages the argument most.
Match the argument's logical skeleton, ignoring its subject.
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Last updated July 9, 2026 · by the theLSATguru team