Necessary AssumptionDiff: Medium
Logic Breakdown
Passage Summary: A teacher tells a student that because every conversation includes a silent promise to tell the truth, the student shouldn't lie for a friend, even if they promised that friend they would.
Conclusion: The student should not lie about Jeanne's health even if they promised Jeanne they would do so.
Reasoning: Breaking promises is inherently wrong, and since speaking involves an implicit promise to be truthful, lying constitutes a broken promise.
Analysis: The teacher is navigating a conflict between two different promises: an explicit one made to a friend and an implicit one made to a listener. To reach the conclusion that the student must tell the truth, the argument relies on the assumption that the implicit promise of honesty carries more weight than the explicit promise to the friend. If the promise to the friend were more important, the conclusion would fall apart. Look for an answer that establishes that the duty to be truthful in speech outweighs other conflicting promises.
Conclusion: The student should not lie about Jeanne's health even if they promised Jeanne they would do so.
Reasoning: Breaking promises is inherently wrong, and since speaking involves an implicit promise to be truthful, lying constitutes a broken promise.
Analysis: The teacher is navigating a conflict between two different promises: an explicit one made to a friend and an implicit one made to a listener. To reach the conclusion that the student must tell the truth, the argument relies on the assumption that the implicit promise of honesty carries more weight than the explicit promise to the friend. If the promise to the friend were more important, the conclusion would fall apart. Look for an answer that establishes that the duty to be truthful in speech outweighs other conflicting promises.
Passage Stimulus
Passage Redacted
Unlock Full Passage11.Which one of the following is an assumption on which the teacher's argument depends?
Correct Answer
D
The argument assumes the implicit truth-telling promise can outweigh the explicit promise to Jeanne. Negation test: If no implicit promise is ever worse to break than any explicit one, then the explicit promise would take priority, pushing the student to lie to keep it—contradicting the teacher’s conclusion. So D is necessary.
Upgrade Your Prep
Ready to go beyond free explanations?
LSAT Perfection is the #1 modern LSAT prep platform, trusted by thousands of students for comprehensive test strategies, advanced drilling, and full analytics on every PrepTest.
Detailed explanations for 59 PrepTests
Advanced drillset builder
Personalized analytics
Built-in Wrong Answer Journal