Sufficient Assumption I: Bridging the Gap
Sufficient Assumption: Bridging the Gap Completely
Necessary Assumption asked for something required but not necessarily enough. Sufficient Assumption asks for a claim that, added to the premises, would make the conclusion airtight — fully closes the gap, no loose ends.
CS Bridge
A sufficient assumption is the missing link in a proof — add it as an axiom and the conclusion follows by pure logic, no further assumptions needed. Contrast with necessary assumption, which is just "this must hold" without guaranteeing the whole chain closes.
1. The Standard: Fully Closes the Gap
Test a candidate answer by asking: "if this is true, together with the stated premises, does the conclusion now follow with certainty?" If yes, it's sufficient — even if it's a much stronger claim than strictly necessary.
2. Sufficient Assumption Answers Are Often "Too Strong" — And That's Fine
Unlike almost every other LR type, an overly strong answer can still be correct here, as long as it fully closes the gap. This is the one place where the LR-TOO-STRONG instinct from other types can mislead you.
3. Bridging Concept Gaps Directly
The cleanest Sufficient Assumption answers directly connect the premise's terms to the conclusion's terms — often almost restating the conditional link needed.
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. Argument: "All members of the design team have UX certification. Therefore, Priya, who has UX certification, must be on the design team." Which assumption, if added, would make this conclusion certain?
LawHub drill-tier LR section, untimed. Scan for Sufficient Assumption / "justify the conclusion" stems.
Tomorrow: formal conditional chains in Sufficient Assumption — where this type gets most mechanical, and most gradable.