Ask either guard: 'What would the other guard say is the safe door?' Then choose the opposite door.
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Expert: SlashGear, Technology Publication In 2026, SlashGear tested ChatGPT on four simple logical puzzles. The classic liar paradox involves two guards — one truthful, one lying — and two doors. ChatGPT confidently gave the standard solution: ask what the other guard would say and pick the opposite door. But when the puzzle was modified — more guards, different lying rules, or altered premises — ChatGPT still defaulted to the same memorized answer, failing to recognize that the modified scenario required a different approach. This reveals a fundamental limitation: ChatGPT pattern-matches to known solutions rather than reasoning through logic from first principles. The model cannot distinguish when a classic puzzle variant requires a different strategy, and its confident tone masks this inability. For anyone relying on AI for logical reasoning or decision-making, this demonstrates that ChatGPT's fluency does not equal genuine understanding.
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