Part-Whole Confusion
LSAT glossary · Law School Admission Test (LSAT)
Definition
An LSAT reasoning flaw that improperly transfers a property between a group and its individual members. Two directions exist: Composition (Part to Whole) infers a property of the whole from a property of its parts — e.g., "each player is outstanding, so the team will outperform every other team." Division (Whole to Part) infers a property of a part from a property of the whole — e.g., "this class collected the most cans, so the top individual collector must be in this class." LSAT phrasing: "infers from the group that an individual..." or vice versa.
Part-Whole Confusion in plain English
Part-whole confusion is sloppily assuming that what's true of a group must be true of each member, or vice versa — but properties don't always transfer between the two. Going part-to-whole: "every player is a star, so the team will crush everyone" ignores that a team can flop if the stars don't mesh. Going whole-to-part: "our class collected the most cans, so the single best collector must be one of us" ignores that our win could come from lots of people each pitching in a little. A choir can sound amazing as a group even if no single singer is a soloist — group traits and individual traits are separate things.
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