LSAT Logical Reasoning — Inference and Resolution (Deep-Dive Study Notes)

Must Be True (MBT)

Questions requiring answers that are logically forced by the given stimulus; must be true given the facts.

MBT vs MSS

MBT asks for what is guaranteed to follow, while MSS looks for the best-supported inference, not necessarily guaranteed.

Key facts for MBT

Treat the stimulus as facts; translate relationships into clear logic; look for conditions that must hold in all scenarios.

Chaining Conditionals

If A → B and B → C, then A → C. This allows deduction of direct relationships.

Contrapositives

If A → B, then not-B → not-A; flipping and negating conditional statements.

Mutual Exclusivity

If X cannot happen with Y, then the occurrence of X implies not-Y.

Quantifier Implications

If all A are B, then anything that is A must also be B.

Use of Answers in MBT

Consider each choice as a hypothesis; prove from the stimulus rather than matching the ‘vibe’.

Most Strongly Supported (MSS)

Aim for the answer that is best backed by the stimulus, even if not guaranteed.

MSS vs MBT

MSS seeks the most supported conclusion; it doesn’t require absolute certainty.

Identifying Support in MSS

Extract key facts, predict direction, and rank answers by evidence support.

Preferred Language in MSS

Choose answers with moderate language; avoid absolutes unless the stimulus justifies them.

Cannot Be True (CBT)

Identify which choice must be false given the facts provided in the stimulus.

CBT vs MBT

MBT requires something to be true in all scenarios, CBT in no scenarios.

Building Possible World for CBT

List constraints from the stimulus and assess each option against them.

Direct Contradiction in CBT

Find answers that directly negate an inference derived from the stimulus.

Resolve the Paradox

Choose the answer that explains how conflicting facts can coexist.

Identifying Discrepancies

Spot two sides of a paradox: what happened and what would be expected.

Hidden Assumptions in Paradox

Focus on assumptions that create unexpected outcomes or discrepancies.

Characteristics of Good Resolutions

Should show cases aren’t comparable, introduce counteracting factors, or clarify measurement effects.

Common Mistakes in Paradox Questions

Rejecting a fact instead of reconciling it or choosing unsupported claims.

Resolution Templates

Articulate what would allow both facts to be true without dismissing one.

Typical MBT Questions

“Which of the following must also be true?” or “Which can be properly inferred?”

Typical MSS Questions

“Which of the following is most strongly supported by the information above?”

Typical CBT Questions

“Which of the following cannot be true?” or “Which scenario is inconsistent with the statements above?”

Typical Resolve the Paradox Questions

“Which of the following, if true, most helps resolve the apparent discrepancy?”

Common Mistake: Confusing CBT with Suggestions

Answers can be unsupported but still possible; identify contradictions.

Key Vocabulary for MBT, MSS, CBT, and Paradox

Understand terms like all, some, only, if, and unless to capture logical relationships.