Logical Reasoning · Weaken

PrepTest 113 · Section 4 · Question 2

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

Step 1 · Pre-Question Guidance · read this first

Question type

Weaken

The one idea it tests

A test proves a part works only if the test hit that part alone; show the result could have come from something next door.

The basic logic

The patty is a test result: poke a small part, get a reaction. The top bun says the small part works. The secret sauce: the reaction came from that part and nothing else. Weaken by showing the poke may have touched other parts too.

Tiny words that decide it

“seems”
“then”
“only”

Playground logic

Tommy pressed near a tiny button on his robot and it beeped, so Marcus declares the tiny button works. The secret sauce is that only the tiny button got pressed; pop it by showing Tommy's thumb may have also hit the big button right beside it.

Step 2 · The kid story

The Mystery Button

Tommy found a tiny button on the back of his old toy robot, smaller than a grain of rice. 'Nobody knows what it does,' he whispered. He pressed it with his thumb, and the robot beeped softly. Marcus pulled out his detective notebook. 'Case closed. The tiny button is a working beep button.' Priya set down her juice box and looked closer. 'Marcus, the big power button is right next to it. Tommy's thumb is about ten times bigger than the tiny button.' Lulu checked with a ruler and nodded. 'So we don't know if the tiny button made the beep, or if the thumb bumped the big one too.' Marcus frowned. 'Then I need a toothpick.' Priya smiled. 'Now you're thinking like a detective.'

Step 3 · Try the model question

Tommy's robot has a tiny button that nobody understands. When Tommy pressed that spot, the robot beeped. So the tiny button is probably a working beep button.

Which fact, if true, would do the most damage to this conclusion?

Step 4 · The courtroom tale

The Case of the Secret Doorbell

A landlord claimed a tenant had installed a hidden doorbell. 'When my inspector pressed the little dot by the door, a chime rang,' the landlord's lawyer said. 'So the dot is a working doorbell.' Mr. Whitfield rose, suspenders snapping. 'Your Honor, the inspector pressed with his whole palm. Right beside that dot is the regular doorbell, which rings the same chime.' He held up a photo. 'We cannot tell which one he pressed.' Judge Marisol Vance peered at the photo. 'So the test did not touch only the dot.' She set down her pen. 'Then this chime proves nothing about the dot. Try again with a pencil eraser, counselor.'

Step 5 · Work the real question

Open PrepTest 113, Section 4, Question 2 in your official copy from LSAC (for example in LawHub) and read it there.

Your answer

How to apply it

Build the burger: the evidence is a test on a small part, the conclusion is that the part works. Name the secret sauce: the test reached that part alone, and the effect came from it. Now pick the choice that cracks that sauce by raising doubt about what the test actually touched. Skip choices that only describe the part as small, simple, or different elsewhere; those leave the test result standing.