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Logical Reasoning · Parallel Flaw

PrepTest 141 · Section 2 · Question 7

Phase 1 (your first ~400 questions): read the guidance, then answer. No clock.

Step 1 · Pre-Question Guidance · read this first

Question type
Parallel Flaw
The one idea it tests
An accusation is dismissed because the accuser once did something similar. That says nothing about whether the accusation is true.
The basic logic
X-Ray the original: Accuser says the accused did wrong. Conclusion: the accusation is baseless. Reason: the accuser did a similar wrong. Find the choice with the same skeleton: dismiss a claim by pointing at the claimer's own past behavior.
Tiny words that decide it
  • “so”
  • “because”
  • “false”

Playground logic

Lulu accuses Tommy of hiding candy. Tommy's top bun: her accusation is baseless. His patty: Lulu hid candy last month. Her past says nothing about whether Tommy did it today.

Step 2 · The kid story

The Pot Calls the Kettle

Lulu marches into the living room with her clipboard. 'Tommy, you are hiding candy in your sock drawer. Mom said no candy before dinner.' Tommy crosses his arms. 'That is totally false. Remember last month? You hid gummy bears in your pencil case! So your accusation is nonsense.' Lulu blinks. 'What I did last month doesn't change what is in your sock drawer right now.' Priya, visiting for a playdate, nods. 'She's right, Tommy. Even if Lulu did hide candy, that doesn't prove you didn't.' Biscuit trots out of Tommy's room with a chocolate wrapper in his mouth. Tommy sighs. 'Okay. That part is true. But the gummy bear thing was also true!' Lulu writes: your past doesn't erase my facts.

Step 3 · Try the model question

Lulu says Tommy is hiding candy in his sock drawer. But this claim is baseless. After all, last month Lulu herself was caught hiding gummy bears in her pencil case.

Which one of these has a flaw most like the flaw in Tommy's reasoning?

Choices

Step 4 · The courtroom tale

The Parade Permit Fight

The baker accused the florist of setting up a stand on the sidewalk without a permit. The florist's lawyer rose before Judge Whitcomb. 'Your Honor, this accusation is groundless. Two years ago, the baker himself put tables on the sidewalk without a permit!' The judge peered over her glasses. 'Counselor, is your client's stand on the sidewalk?' 'Well, yes.' 'Does she have a permit?' 'Not exactly.' 'Then the baker's past mistake does not make his claim false. A person with a messy record can still be telling the truth.' She fined the florist and, for good measure, asked the baker about those old tables.

Step 5 · Work the real question

Open PrepTest 141, Section 2, Question 7 in your official copy from LSAC (for example in LawHub) and read it there.

Your answer

How to apply it

Break the original into parts: who accuses, what the conclusion says about the accusation, and what reason is given. Notice the reason is about the accuser's own past conduct. Then X-Ray each choice for the same parts in the same roles. The match must conclude the accusation is false or baseless, and its reason must be the accuser's similar behavior. Extra details can be present. Reject choices that conclude something else, like hypocrisy, or give a different kind of reason.