Logical Reasoning · Principle (Justify the Application)

PrepTest 153 · 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

Question type

Principle (Justify the Application)

The one idea it tests

To justify applying a rule, show that the case actually meets the rule's trigger condition.

The basic logic

The principle has a trigger (someone makes a mistake) and a result (using it for gain is wrong). The application only shows the result side: someone used something for gain. The right answer supplies the missing trigger: the advantage came from the other person's mistake.

Tiny words that decide it

“if”
“error”
“only because”

Playground logic

The rule's patty needs two pieces: Owen slipped up, and Marcus used the slip to win. The story says Marcus used Owen's plan to win, but not that Owen slipped. The answer fills in the slip: Owen accidentally left the plan out.

Step 2 · The kid story

The Drawing Contest Mix-Up

Ms. Rivera has a fairness rule: if a classmate makes a mistake, it is unfair for someone else to use that mistake to win. During the drawing contest, Marcus used Owen's secret drawing plan and won the blue ribbon. Nadia shouts, "Unfair!" Lulu checks her clipboard. "Wait. The rule only kicks in if Owen made a mistake. Did he?" They investigate. If Owen gave Marcus the plan as a gift, nobody made a mistake. But it turns out Owen accidentally left his plan face up on the shared art table. Marcus saw it only because of that slip. Now the rule fits. Priya nods. "Mistake, then used to win. Both pieces. Unfair."

Step 3 · Try the model question

Rule: If a classmate makes a mistake, it is unfair for another student to use that mistake to win. Application: Marcus used Owen's secret drawing plan to win the contest, so Marcus acted unfairly.

Which fact, if true, best backs up using the rule this way?

Step 4 · The courtroom tale

The Case of the Open Gate

A farmer, Ms. Hale, sued her neighbor. "The county rule says: if a neighbor makes a mistake, it is wrong for another neighbor to profit from it. He sold eggs from my hens!" Mr. Whitfield, for the neighbor, smiled. "Your Honor, the rule needs a mistake. Where is it?" Judge Ruiz turned to Ms. Hale. "How did your hens reach his yard?" "I forgot to latch my gate one evening. They wandered over, and that is the only way he got them." The judge nodded. "Then we have the mistake, and we have the profit. The rule fits." Mr. Whitfield checked his notes. "I may need a new strategy."

Step 5 · Work the real question

Open PrepTest 153, Section 2, Question 6 in your official copy from LSAC (for example in LawHub) and read it there.

Your answer

How to apply it

Split the principle into its trigger and its result. Compare that to the application: which piece is already shown and which is missing? Usually the application shows the result but leaves the trigger unproven. Look for the choice that makes the trigger true for this case, ideally showing the advantage came only from the other person's slip.