Conditional Rule
LSAT glossary · Logical Reasoning
Definition
A Logical Reasoning relationship of the form “If A, then B” (A → B). Translate it precisely, write the contrapositive (¬B → ¬A), and test whether it chains with another conditional; do not reverse it or negate only one side.
Conditional Rule in plain English
A conditional rule is an "if-then" promise: "If A happens, then B must happen" (written A → B). The key trick is that every such promise secretly contains a mirror version called the contrapositive: if B did NOT happen, then A couldn't have happened either (¬B → ¬A) — same truth, flipped and negated. Think of "if it's raining, the ground is wet": that also guarantees "if the ground is dry, it isn't raining." You must write out that mirror version every time, because ignoring it means you're only using half the clue's power — and sometimes two conditionals can be chained together (A → B → C) to reveal hidden facts.
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Practice Conditional Rule
If the planner's statements are true, which one of the following must also be true?
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