Logical Reasoning · Weaken (EXCEPT)

PrepTest 116 · Section 3 · Question 17

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

Step 1 · Pre-Question Guidance · read this first

Question type

Weaken (EXCEPT)

The one idea it tests

In a 'whodunit by elimination' argument, anything that reopens the suspect list, weakens the clue, or tilts the odds back toward the other group weakens it.

The basic logic

Map the chain: (1) the culprit needed certain things, so it was someone in group A or group B, (2) a clue makes group A unlikely, (3) so probably group B. Four answers will pop one of those steps. The correct answer (the EXCEPT) leaves every step standing; often it is general, true of everyone, or about something before or beside the question of who.

Tiny words that decide it

“EXCEPT”
“either or”
“probably”
“likely”

Playground logic

Marcus says the cupcake thief needed the key, so it was a hall monitor or a line leader; hall monitors are too neat to leave crumbs; so a line leader did it. Four facts pop that argument. The right answer is the one that leaves Marcus's chain untouched.

Step 2 · The kid story

The Cupboard Cupcake Caper

The last cupcake has vanished from Ms. Rivera's locked cupboard. Marcus puts on his detective hat. "Whoever took it needed the cupboard key and knew which shelf the treats are on. Only hall monitors and line leaders know both. Hall monitors are super neat, so they'd never leave this crumb trail. So it was probably a line leader!" Tommy, who knows a thing or two about hidden treats, raises an eyebrow. Priya counts on her fingers. "What if the line leaders were on a field trip? What if Mr. Whiskers knocked over an old muffin and made the crumbs? What if a hall monitor had frosting on her sleeve?" Lulu adds, "Or hall monitors are only neat when someone's watching." Marcus gulps. "Okay, okay. But some facts don't change anything." Lulu writes: cupcakes are Ms. Rivera's favorite. Not helpful.

Step 3 · Try the model question

Marcus: Whoever took the cupcake needed the cupboard key and knew which shelf held the treats, so it must have been a hall monitor or a line leader. But a hall monitor, being very neat, probably would not have left the crumb trail that revealed the theft. So the thief was most likely a line leader.

Suppose each choice is true. Every one hurts Marcus's reasoning EXCEPT:

Step 4 · The courtroom tale

The Case of the Missing Trophy

In a made-up school-board trial, the trophy has vanished from the glass case. The prosecutor argues: "Only coaches and janitors have case keys. Coaches would never smudge the glass like this. So probably a janitor." Mr. Whitfield lists his objections. "Your Honor, the coaches were alone in the building that night. The smudges match the window washer's gloves. And one coach was seen carrying a heavy duffel bag." The prosecutor fires back, "And the trophy was very shiny!" Mr. Whitfield smiles. "True, and it changes nothing. Shiny or dull, the question is who took it." The judge nods. "Three objections land. The shine is just shine."

Step 5 · Work the real question

Open PrepTest 116, Section 3, Question 17 in your official copy from LSAC (for example in LawHub) and read it there.

Your answer

How to apply it

Map the argument as steps: what the culprit needed, the two groups that fit, the clue against one group, and the conclusion about the other. For each choice, ask which step it attacks: widening the suspect pool, undercutting the clue, or shifting the odds back. Cross out each choice that pops a step. The answer is the one that leaves every step standing, often a general fact that applies no matter who did it.