Parallel Reasoning I: Matching Argument Structure
Parallel Reasoning I: Matching Argument Structure
Parallel Reasoning asks which answer choice uses the same reasoning structure as the stimulus — same skeleton, different topic entirely.
CS Bridge
This is structural isomorphism — two functions with different variable names but identical control flow. Strip the topic, keep the shape: number of premises, their logical type (causal, conditional, statistical), and how they connect to the conclusion.
1. Abstract the Shape First
Before reading answer choices, describe the stimulus's structure in the abstract: "two premises, one stating a general rule, one stating a specific case, concluding the case satisfies the rule."
2. Match the Flaw Too, If Present
If the stimulus contains a flaw, the parallel structure should contain a flaw of the same type — a valid argument won't correctly parallel a flawed one, and vice versa (see Parallel Flaw, two days from now).
3. Count of Premises and Conclusion Strength
Match the number of premises and whether the conclusion is definite, comparative, or conditional — structural mismatches here eliminate choices fast.
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. Stimulus: "All roses need sunlight. This plant is a rose. So this plant needs sunlight." Which choice has the same structure?
LawHub drill-tier LR section, untimed. Scan for Parallel Reasoning stems.
Formal/conditional Parallel Reasoning tomorrow, where structure-matching gets fully mechanical.