A Royal Conundrum Ends in Double Death
In a tale fit for a dark fairy tale, two master poison makers met their end in a shocking turn of events during a royal ceremony designed to crown the creator of the most potent toxin. The Queen, seeking to determine whether Smith or Jones manufactured the stronger poison, orchestrated a deadly drink-off that concluded with both participants dead, leaving court observers baffled.
The Puzzle's Prestigious Pedigree
This brilliant lateral thinking puzzle is credited to the legendary computer scientist Michael Rabin, who first posted it to an electronic bulletin board at Carnegie Mellon University in the late 1980s. Recently resurrected by a dedicated puzzle enthusiast, it has been brought to wider attention thanks to mathematician Timothy Chow of the Centre for Communications Research in Princeton, New Jersey, who published an analysis in Mathematics Magazine.
The puzzle involves no cheap tricks but requires genuine lateral thought. The solution hinges on basic game theory, where both participants, acting in their own self-interest based on their predictions of the other's actions, create a fatal outcome neither intended.
The Rules of the Deadly Game
The puzzle is set in a faraway land where the following facts are universally known and true:
- A person who ingests a poison will die within the hour UNLESS they subsequently ingest a stronger poison, which acts as an antidote and restores complete health.
- Smith and Jones are the only manufacturers of poison.
- Each produces several types of poison, all with different strengths.
- Neither has access to the other's poisons.
With no public knowledge of who made the strongest poison, the Queen summoned the duo to her palace. She issued a chilling decree: in one week, they were to return, each bringing a vial of their own poison. The ceremony would proceed as follows:
- Both would take a swig from the *other* person's vial.
- Both would then take a swig from their *own* vial.
- They would be watched carefully for one hour.
The Queen emphasised that it was in their interest to bring their strongest poison, as the one with the superior toxin would survive, while the other would die. Trained observers ensured no cheating was possible.
A Shocking Outcome Defies Expectations
Smith and Jones departed, deeply disturbed. Neither wished to die, and neither was confident of possessing the strongest poison. With no way to access the other's arsenal, they spent the entire week desperately strategising for survival.
At the appointed time, the ceremony unfolded exactly as prescribed. Both participants drank from the other's vial, then from their own. After being watched for an hour, both Smith and Jones keeled over and died. The Royal Coroner confirmed the cause: poisoning.
This astonishing result forms the core of the puzzle. How could this double fatality have occurred? The answer lies not in treachery, but in the cold, logical application of game theory, where individual rational choices lead to a collectively tragic end.
