Day 26 / 168 Week 5 of 28 Phase 2: Logical Reasoning Deep Dive

Flaw V: Numbers vs Percentages, Absence of Evidence, False Choice & Circularity

🕑 ~75 min · Archetype A — LR Deep Dive

Recap: Flaw, Part 5 — The Rest of the Vocabulary

The final Flaw day. Four more named patterns round out the Flaw vocabulary before it gets folded into every later question type.

1. Numbers vs. Percentages (revisited, generalized)

Beyond Day 21's specific case: any confusion between an absolute quantity and a rate/proportion.

2. Absence of Evidence

Treating "no evidence of X" as proof of "not X" — a specific, commonly tested flaw pattern.

3. False Choice

Presenting only two options when others exist, then arguing against one to support the other.

4. Circular Reasoning

The conclusion is assumed, in different words, as one of the premises.

Practice items on this page are curriculum-authored in LSAT style; they are not official LSAC questions. Real drilling happens on LawHub — see the assignment below.

Q1. Argument: "No study has found that the supplement is harmful. Therefore, the supplement is safe." What's the flaw?

A. Ad hominem

B. Treats absence of evidence of harm as proof of safety

C. Equivocation

D. Composition

Correct answer: B. Lack of proof of harm isn't the same as proof of safety — the classic absence-of-evidence flaw.

Q2. Argument: "Either we cut the budget or the program fails. We shouldn't cut the budget. So the program will fail." What's the vulnerability?

A. A valid argument with no flaw

B. False choice — assumes only two options exist when other outcomes may be possible

C. A causal reversal

D. A sampling flaw

Correct answer: B. Unless the stimulus establishes these are truly the only two possibilities, presenting just two options is a false-choice flaw.

LawHub drill-tier LR section, untimed. Scan for Flaw stems only — last dedicated Flaw drill before it becomes a recurring background skill.

Necessary Assumption starts tomorrow, opening the assumption/gap family with the single highest-leverage LR technique: the negation test.

← Day 25: Flaw IV: Equivocation, Part–Whole, Ad Hominem & Appeals Day 27: Necessary Assumption I: The Negation Test →