Logical Reasoning · Flaw

PrepTest 119 · Section 3 · Question 13

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

Having a trait that goes with another trait does not mean more of the first gives more of the second.

The basic logic

The premise is a tendency: people who have quality X usually have quality Y. The conclusion is a scale: the more X, the more Y. That jump from 'goes together' to 'rises together' is a Scope Shift. Name the gap in general terms.

Tiny words that decide it

“tend to”
“the more”
“so”

Playground logic

Marcus's patty says chess kids tend to be good at puzzles. His top bun says the better at chess, the better at puzzles. That is a Scope Shift: a yes-or-no link has been stretched into a sliding scale.

Step 2 · The kid story

Marcus and the Puzzle Ladder

Marcus stood in front of the chess club with his detective notebook. "Fact: kids who play chess are usually good at math puzzles. Therefore, the better you are at chess, the better you are at puzzles. Owen is our best chess player, so he must be the puzzle king." Ms. Rivera handed out a puzzle sheet. Nadia, who plays chess only a little, finished first. Owen finished in the middle, scratching his head. Marcus stared. "But my logic!" Priya sipped her juice box. "Your clue said chess kids tend to be good at puzzles. It did not say that more chess means more puzzle skill. Those are two different claims." Lulu wrote it down: 'Goes together is not grows together.'

Step 3 · Try the model question

Kids who play chess are usually good at math puzzles. So the better a kid is at chess, the better that kid will be at math puzzles.

Marcus's reasoning is weakest because it

Step 4 · The courtroom tale

The Case of the Tallest Guard

Mr. Whitfield addressed the jury. "Basketball players are generally tall. Therefore, the better the basketball player, the taller he must be. My client is the best player in the league, so he must be the tallest, and he could easily have reached the top shelf where the trophy was hidden." The prosecutor, Mr. Okafor, rose. "Your Honor, counsel moved from 'players tend to be tall' to 'better players are taller.' That does not follow. The league's best player is actually one of its shortest." The judge nodded. "A tendency is not a ladder, Mr. Whitfield."

Step 5 · Work the real question

Open PrepTest 119, Section 3, Question 13 in your official copy from LSAC (for example in LawHub) and read it there.

Your answer

How to apply it

Find the premise and ask what kind of link it gives: a tendency, a rule, or a scale. Then find the conclusion and ask what kind of link it claims. If the premise says two things tend to go together and the conclusion says one rises with the other, that is your gap. Pick the choice that names that shift in abstract words, and ignore choices describing gaps the argument does not have.