Logical Reasoning · Sufficient Assumption

PrepTest 113 · Section 2 · Question 5

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

Step 1 · Pre-Question Guidance · read this first

Question type

Sufficient Assumption

The one idea it tests

If a tool can only explain two kinds of things, and the target needs more than those two, the tool cannot explain the target.

The basic logic

The patty: this kind of theory can explain only items X and Y. The top bun: it cannot explain Z. The magic key links the two: explaining Z requires more than explaining X and Y. Click it in, and the conclusion locks.

Tiny words that decide it

“only”
“no”
“thus”

Playground logic

Lulu says recipe cards can explain only ingredients and steps, so no recipe card can explain why Grandma's cookies feel like home. The magic key: explaining that feeling takes more than ingredients and steps. Click, the door opens.

Step 2 · The kid story

The Recipe Card Mystery

Grandma's oatmeal cookies made everyone smile. Kevin wanted to know why. 'I'll find the recipe card!' he said. 'Then I'll know everything.' Lulu checked the card on her clipboard. 'This card lists ingredients and tells you the steps. That's all a recipe card can ever do.' Kevin munched. 'But these cookies feel like a cozy blanket. Like home.' Lulu nodded. 'So no recipe card can explain that feeling.' Marcus jumped in. 'Wait, how do you know?' Priya sipped her juice box. 'Lulu needs one more piece. If explaining the cozy feeling takes more than ingredients and steps, then a card that only does ingredients and steps can't do it. Click. Done.' Kevin nodded slowly. 'Also, a stegosaurus would love these.'

Step 3 · Try the model question

Lulu: Although the cozy feeling Grandma's cookies give seems to come from baking them, a recipe card can explain only what ingredients go in and what steps to follow. So no recipe card can explain that cozy feeling.

Which choice, if assumed, makes Lulu's conclusion airtight?

Step 4 · The courtroom tale

The Case of the Map and the Mood

Mr. Whitfield faced the jury. 'A map can show only where roads go and how far apart towns are. So no map can explain why the drive along Sunflower Lane makes people so cheerful.' Judge Amos Keel leaned forward. 'Counselor, you need a link. Why can't road lines and distances explain cheerfulness?' Mr. Whitfield smiled. 'Because, Your Honor, explaining that cheer requires more than explaining road paths and distances. The smell of flowers, the songs on the radio, the sunshine.' The judge tapped his gavel. 'With that added, the case is airtight. A map simply does not cover enough. Ruling granted.'

Step 5 · Work the real question

Open PrepTest 113, Section 2, Question 5 in your official copy from LSAC (for example in LawHub) and read it there.

Your answer

How to apply it

Find the limit placed on the tool in the premise: it covers only certain things. Then find what the conclusion says it cannot do. Build the bridge: the target requires more than those certain things. Run the Click Test on each choice: if added, does the conclusion become guaranteed? Reject choices that only restate the limit, that suggest the target is fully covered, or that talk about things never linked to the target.