Treat repeated challenges as a signal to re-examine the assumption, not as a debate you need to win.

First restate the assumption and the evidence behind it. Then identify what would make it wrong and whether the interviewer has introduced a new fact or simply wants stronger reasoning.

If the logic still holds, defend it briefly and invite a test. If new information weakens it, update the assumption openly.

The goal is to show intellectual flexibility under pressure: neither collapsing immediately nor stubbornly repeating the same answer.

The advice I got was to avoid defending the first idea just because I said it first. Updating your view is part of the case.