Day 32 / 168 Week 6 of 28 Phase 2: Logical Reasoning Deep Dive

Sufficient Assumption II: Formal Chains & "Justify the Conclusion"

🕑 ~80 min · Archetype A — LR Deep Dive

Sufficient Assumption II: Formal Chains

The most mechanical version of Sufficient Assumption: stimuli built entirely from conditional statements, where the correct answer is the missing link that completes a chain from premise to conclusion.

1. Diagram Everything

When a stimulus is conditional-heavy, diagram every statement using Day 4/8 notation. The conclusion is itself a conditional (or a specific instance of one); trace the chain from the premises and find where it breaks.

2. The Missing Link

Often the gap is a single missing arrow that would connect two pieces of an otherwise-complete chain. The correct answer supplies exactly that arrow.

3. "Justify the Conclusion" Phrasing

This exact phrase is the most common Sufficient Assumption stem — treat it as a synonym for "which assumption, if true, guarantees the conclusion."

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. Given "A → B" and "B → C" and the conclusion "A → C," is any additional assumption needed?

A. Yes, a strong one

B. No — the chain A→B→C already validly yields A→C by transitivity

C. Yes, but only a necessary assumption

D. Cannot be determined

Correct answer: B. This chain is already complete and valid — no sufficient assumption is needed, since transitivity already closes the gap.

Q2. Given "A → B" and the conclusion "A → C," which assumption would justify the conclusion?

A. C → A

B. B → C

C. A → B (already given)

D. ¬C → ¬A

Correct answer: B. Adding B→C completes the chain A→B→C, which validly yields A→C.

LawHub drill-tier LR section, untimed. Scan for conditional-heavy Sufficient Assumption stimuli specifically.

Strengthen starts tomorrow — the first type where the correct answer only needs to help, not fully prove, which is a real shift in standard from everything in the assumption family so far.

← Day 31: Sufficient Assumption I: Bridging the Gap Day 33: Strengthen I: Closing the Gap From the Other Side →