Logical Reasoning · Flaw
PrepTest 101 · Section 2 · Question 6
Phase 1 (your first ~400 questions): read the guidance, then answer. No clock.
Step 1 · Pre-Question Guidance · read this first
- “each”
- “different”
- “none of them”
- “therefore”
Playground logic
Every drawing in the contest is different. Marcus says no other drawing is like his, so his should win. But by the same logic no drawing is like any other, so 'unique' fits all of them and picks out no one.
Step 2 · The kid story
The One-of-a-Kind Drawing
Ms. Rivera hung up everyone's drawings of their pets for the art contest. Marcus pointed at his own. 'Mine should win. Look at all the others. Not one of them is like mine. Mine is totally unique.' Owen frowned. 'Every drawing is different, Marcus. Mine is the only one with a hamster in a spaceship.' Nadia added, 'Mine is the only one of a turtle in a tutu.' Kevin said, 'Mine is a dinosaur. Also a pet. Also unique.' Lulu checked her clipboard. 'If everybody's drawing is one of a kind, then being one of a kind doesn't make yours the winner.' Marcus looked at his drawing of Biscuit wearing sunglasses. 'It's still really good,' he mumbled. 'Then say why it's good,' said Priya kindly.
Step 3 · Try the model question
Every drawing in the contest shows a different pet in a different way. Compared with Marcus's drawing, none of the others is exactly like it. So Marcus's drawing should win.
Marcus's reasoning is flawed because it
Step 4 · The courtroom tale
The Fingerprint Defense
A prosecutor pointed at the defendant. 'This man's fingerprints are unlike anyone else's in the city. No one else has his prints. That makes him the obvious suspect!' Mr. Whitfield rose slowly. 'Your Honor, my fingerprints are also unlike anyone else's. So are yours. So are the prosecutor's.' Laughter rippled through the courtroom. 'Having one-of-a-kind prints sets no one apart, because all of us have them. Now, if the prints at the scene matched my client, that would be evidence. Do they?' The prosecutor shuffled papers. 'We have not checked.' The judge sighed. 'Then come back when you have something that only he has.'
Step 5 · Work the real question
Open PrepTest 101, Section 2, Question 6 in your official copy from LSAC (for example in LawHub) and read it there.
Your answer
How to apply it
Find the top bun: one person in a group is declared the best. Find why that one gets picked. Then reread the bottom bun and ask whether it already says the same kind of thing about every member. If it does, pre-phrase the flaw: the argument uses a feature the whole group shares to set one member apart. Pick the answer naming that move. Eliminate choices naming flaws that never happen here (Phantom Pieces) and ones that sound like a familiar flaw but do not fit (Matching Costumes).