Flaw questions are pattern recognition. The LSAT recycles the same small menu of reasoning errors across thousands of questions, describing them in abstract language ("takes for granted," "fails to consider," "confuses"). If you learn the menu, you can prephrase the flaw before reading the choices — which turns the hardest LR type into one of the fastest.
The 8 classic flaws:
- Correlation → causation. "Towns with more libraries have higher literacy, so libraries cause literacy." Ignores the obvious alternative: wealth causes both. Watch for "associated with," "linked to," "correlated."
- Unrepresentative sample. "We surveyed our subscribers, and 90% love the product." The sample chose itself. Ask: who was excluded?
- Equivocation. A key word shifts meaning mid-argument. "Banks hold our money; river banks hold water; therefore…" — an extreme example, but the LSAT does this subtly with words like "value," "free," or "natural."
- Part-to-whole / whole-to-part. "Each brick is light, so the wall is light" (part→whole); "The team is championship-caliber, so every player is a star" (whole→part). Properties of parts need not transfer.
- Straw man. Distorts the opponent's position, then attacks the distortion. "Critics of the tax cut want the poor to suffer" — no critic said that.
- Ad hominem. Attacks the person instead of the claim. "You can't trust his climate research — he drives a sports car." The car is irrelevant to the data.
- False dilemma. "Either we ban cars downtown or accept permanent gridlock." Two options presented as exhaustive when others exist (congestion pricing, better transit).
- Appeal to popularity / tradition / authority. "Everyone does it," "we've always done it this way," "a celebrity endorses it." None of these make a claim true.
How the LSAT phrases them. The correct answer rarely says "straw man." It says the argument "attacks a distorted version of the position it opposes," or "presumes, without justification, that what is true of a part is true of the whole." Learn to translate: read the abstract choice and ask which menu item it describes.
The method: (1) identify conclusion and premises; (2) name the gap between them in plain words ("just because two things rise together doesn't mean one causes the other"); (3) match your plain-words flaw to the menu; (4) find the choice that describes it. Prephrase first — students who read choices first get seduced by attractive wrong answers.
Key takeaways
- Flaw is pattern recognition: learn the 8-item menu cold.
- Prephrase the flaw in plain words before touching the choices.
- Translate abstract answer language back to the menu ("fails to consider" = ignored alternative).
- The gap between premises and conclusion is always where the flaw lives.