Day 14 / 168 Week 3 of 28 Phase 1: Diagnostic + Foundations

Assumptions: Finding the Gap Between Premises and Conclusion

🕑 ~75 min · Archetype A — LR Deep Dive

Recap: The Gap

Every LR argument leaves something unsaid that it needs to be true for the conclusion to follow from the premises. Today is about training your eye to spot that gap directly, before Week 5 formalizes it into Necessary and Sufficient Assumption questions.

CS Bridge

An unstated assumption is an implicit dependency your function relies on but never checks — like code that assumes a list is non-empty without validating it. The argument "works" as long as the assumption holds; find the case where it doesn't, and you've found the gap.

1. The Concept-Shift Gap

The premise talks about one concept, the conclusion talks about a related-but-different one, and the argument assumes they're close enough. ("Sales rose" → "the marketing campaign worked" assumes nothing else caused the rise.)

2. The Scope-Shift Gap

The premise supports a claim about some/most of a group; the conclusion claims something about all of it (or vice versa).

3. The Alternative-Possibility Gap

The argument assumes no other explanation/option exists, without ruling any out.

4. Practicing the Search

For any argument, ask: "what would have to be true for these premises to actually get me to this conclusion, that the stimulus never says outright?" That answer is the assumption — and it's exactly what Necessary and Sufficient Assumption questions ask you to identify or supply.

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: "The new hire has a PhD in economics. Therefore, she will be an excellent policy analyst." What unstated assumption does this argument require?

A. A PhD is required for the job

B. Having a PhD in economics correlates with being a good policy analyst

C. All policy analysts have PhDs

D. She applied for the job

Correct answer: B. The argument jumps from a credential to a job-performance conclusion — it assumes the credential predicts the performance, without which the premise doesn't support the conclusion.

Q2. Argument: "Most respondents in the survey preferred Brand A. So the company should switch its flagship product line to Brand A's formula." What gap does this argument contain?

A. A scope-shift gap: "most respondents" is treated as if it settles the decision for "the company," ignoring cost, feasibility, and non-respondent customers

B. No gap; the conclusion follows directly

C. A conditional-logic gap

D. A causal-reversal gap

Correct answer: A. Survey preference among respondents doesn't, by itself, establish that switching formulas is the right business decision — that's a scope/relevance gap.

LawHub drill-tier LR section, untimed. For each stimulus, write one sentence naming the gap before reading the question stem.

Back to RC: viewpoints and author's attitude, building directly on Day 3's viewpoint inventory.

← Day 13: Role of a Statement (Argument Part) Questions Day 15: RC Viewpoints, Author's Attitude & Tone Words →