Logical Reasoning · Flaw

PrepTest 114 · Section 4 · Question 21

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

Step 1 · Pre-Question Guidance · read this first

Question type

Flaw

The one idea it tests

Showing that X is neither required for Y nor a guarantee of Y does not show that X fails to help Y. The flaw is a Scope Shift from 'always produces' to 'helps.'

The basic logic

Look for counterexamples on both sides: cases with X but no Y, and cases with Y but no X. Those knock out 'always' and 'only.' But 'promotes' just means makes Y more likely. The argument overlooks that middle ground.

Tiny words that decide it

“promote”
“some”
“without”

Playground logic

Marcus's patty: Owen went to homework club and still got a C, and Nadia skipped it and got all A's. His top bun: the club does not help grades. Priya spots the Scope Shift: the club might still raise grades for most kids, even though it is not a sure thing and not the only path.

Step 2 · The kid story

The Homework Club Verdict

Marcus stood on the cafeteria bench. 'I have cracked the case. Homework club does not help grades!' Kevin looked up from his pineapple pizza. 'How do you know?' 'Evidence one: Owen goes to homework club every single day and still got a C in spelling. Evidence two: Nadia never goes, and she got all A's.' Priya set down her juice box. 'Those two clues show the club is not a guarantee, and it is not the only way to get good grades. But help is a smaller word than guarantee. The club could still give most kids a boost.' Lulu wrote on her clipboard: 'Not always, not only, but maybe helps.' Marcus sat back down, slowly.

Step 3 · Try the model question

Marcus: Homework club does not help students get better grades. Owen attends homework club every day, yet he got a C. Nadia has never attended, yet she got all A's.

Which criticism best describes the problem with Marcus's reasoning?

Step 4 · The courtroom tale

The Case of the Alarm Clocks

A clock maker was accused of false advertising for saying its alarm clocks help workers get to work on time. The prosecutor announced: 'Your Honor, Mr. Daly owns this alarm clock and was late twice last week. Ms. Pham owns no alarm clock and has never been late. So these clocks do not help anyone be on time.' Mr. Whitfield rose. 'Your Honor, the prosecutor has proved two things. The clock is not a guarantee, and it is not the only way to be punctual. Fine. But helping is a smaller claim than guaranteeing. The clock can still make lateness less likely.' The judge set down her coffee. 'The ad stands.'

Step 5 · Work the real question

Open PrepTest 114, Section 4, Question 21 in your official copy from LSAC (for example in LawHub) and read it there.

Your answer

How to apply it

Spot the conclusion: X does not promote or help Y. Then sort the evidence. Which examples show X without Y? Which show Y without X? Those only rule out 'always' and 'only.' Ask yourself whether X could still raise the odds of Y. Pick the choice that names this gap between helping and being required or a guarantee. Reject choices that describe things the argument never does (Phantom Piece).