Logical Reasoning · Method of Argument

PrepTest 132 · 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

Method of Argument

The one idea it tests

When it is nearly certain that one of two options will happen, ruling out one makes the other nearly certain.

The basic logic

Track the strength words. The premise says almost surely one of two. The new fact removes one. The conclusion says almost surely the other. Describe that move in abstract terms, keeping the 'almost' level of confidence.

Tiny words that decide it

“either”
“virtually”
“therefore”
“almost”

Playground logic

Kevin's patty: the class pet will almost surely be named either Captain Fluff or Noodle, and Ms. Rivera just ruled out Noodle. His top bun: so Captain Fluff is almost certainly the winner. The move: knock out the only other likely contender, and the one left standing becomes extremely likely.

Step 2 · The kid story

Naming the Hamster

Ms. Rivera's class got a hamster, and everyone voted on a name. By lunch, Kevin had the scoop. 'It's basically a two-horse race,' he said, mouth full of pineapple pizza. 'Either Captain Fluff or Noodle. Nobody else is close. Somebody voted Tyrannosaurus, but that was me.' Then Owen ran in. 'Ms. Rivera said Noodle is out! It's already the name of the class goldfish.' Kevin grinned. 'Then it's almost certainly Captain Fluff.' Priya nodded slowly. 'Not totally certain. A surprise name could still sneak in. But you knocked out the only other real choice, so almost certain sounds right.' Kevin raised his pizza like a trophy. 'Long live Captain Fluff!' The hamster, unaware, kept running on its wheel.

Step 3 · Try the model question

Kevin: It is nearly certain that the class hamster will be named either Captain Fluff or Noodle. Ms. Rivera just announced that Noodle cannot be used. So the hamster will almost certainly be named Captain Fluff.

Kevin's argument proceeds by

Step 4 · The courtroom tale

The Case of the Missing Trophy

Mr. Whitfield paced. 'Your Honor, the bowling trophy was surely taken by one of two people: the janitor or the team captain. Nobody else had a key.' He spun around. 'This morning the janitor proved he was at his sister's wedding all weekend. Therefore, it is almost certain the captain took the trophy.' The judge tapped her pen. 'Almost certain, counselor? Not certain?' 'Almost, Your Honor. Someone could have copied a key. But with the only other likely person ruled out, the captain is by far the best bet.' The judge nodded. 'A careful claim. I appreciate the word almost.'

Step 5 · Work the real question

Open PrepTest 132, Section 4, Question 21 in your official copy from LSAC (for example in LawHub) and read it there.

Your answer

How to apply it

Find the premise that narrows things to a couple of likely options and note its confidence level. Find the new fact that removes one option. Check that the conclusion picks the remaining one at the same rough confidence. Choose the answer that describes knocking out the sole other likely option. Test every word of each description against the argument, and drop any that names a step the argument never takes.