Logical Reasoning · Flaw

PrepTest 134 · Section 2 · Question 2

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

Two things show up together, and the arguer assumes one causes the other without checking whether the arrow points the other way.

The basic logic

The evidence shows that A and B travel together in two different groups. The conclusion says A causes B. Ask: could B cause A instead? If the argument never rules that out, it has a Backwards Arrow (a kind of Rooster).

Tiny words that decide it

“causes”
“likely”
“tends to”
“so”

Playground logic

Marcus sees that kids who wear lucky socks lose more games, so he concludes the socks cause losing (top bun). The hidden sauce is that losing could not cause the socks, but maybe kids who keep losing start wearing lucky socks. That is a Backwards Arrow.

Step 2 · The kid story

Marcus and the Cursed Socks

Marcus pinned a chart to the clubhouse wall. 'Detective report. I watched the four-square games for two weeks. Kids who wear lucky socks lose way more often than kids who don't. Also, Owen's cousin's soccer team wears lucky socks every game, and they lose all the time.' He tapped the chart. 'So lucky socks probably cause losing. Throw them out!' Owen looked down at his striped socks. Lulu raised her clipboard. 'Marcus, why did people start wearing lucky socks?' 'Because they wanted luck, I guess.' 'And who wants luck the most?' Priya smiled over her juice box. 'The kids who were already losing. Maybe losing makes people put on lucky socks, not the other way around.' Marcus stared at his chart. 'My arrow is pointing backwards, isn't it?'

Step 3 · Try the model question

Marcus: Over two weeks, kids who wore lucky socks lost at four-square more often than kids who did not. And a soccer team that always wears lucky socks loses often too. So lucky socks very likely tend to cause losing.

Marcus's reasoning is open to which criticism?

Step 4 · The courtroom tale

The Case of the Gloomy Umbrellas

Prosecutor Dana Pike paced the room. 'Your Honor, in our town survey, people who carry umbrellas are grumpy far more often than people who do not. And the mail carriers, who carry umbrellas all year, are famously grumpy. So umbrellas very likely cause grumpiness. Ban the umbrella shop!' Mr. Whitfield stood and snapped a suspender. 'Your Honor, think about who carries umbrellas. People who are out in the rain. And what does standing in the rain do to a person's mood?' The judge sighed. 'So the grumpy weather might come first, and the umbrellas follow.' 'Exactly. The prosecutor drew her arrow backwards.' 'Motion denied.'

Step 5 · Work the real question

Open PrepTest 134, Section 2, Question 2 in your official copy from LSAC (for example in LawHub) and read it there.

Your answer

How to apply it

Find the conclusion and check whether it claims that one thing causes another. Then look at the evidence: does it only show the two things appearing together? If so, run through the Rooster family. Ask first whether the second thing could produce the first. Then pick the choice that names the missed possibility in the argument's structure. Skip choices that attack small details, definitions, or claims the argument never made.