# The king and two poisons [duplicate]

There is a kingdom and in the kingdom when you drink a poison the only way to cure yourself is to drink a stronger poison to neutralize it. The King wants to make the strongest poison possible in order to make sure he can neutralize any other poison he may be given. To do this he enlists the two best chemists of the land: Tom and Bob.

The king is going to have them both create a poison as strong as they can then have them drink the other person's poison then their own. Whoever dies created the weaker poison. Tom knows that Bob is much better at making poisons and he is sure to make a stronger poison. Knowing this, Tom makes a plan that ensures he lives and Bob dies.

The day of the contest arrives and Bob realizes that Tom must have known he had no chance against his prowess as a poison maker. So Bob thinks quickly and creates a new plan that ensures that once again he will live and Tom will die.

In the end Bob lives, Tom dies, and the King doesn't get what he wants.

What happened?

• My riddle does not include different 6 poisons. – user49257 May 28 '18 at 9:55
• It is the exact same mechanic though (and as that puzzle reveals, both people can ensure survival) – phenomist May 28 '18 at 10:09
• Indeed, that puzzle makes things more explicit, which makes it a better worded puzzle. – phenomist May 28 '18 at 10:41
• This puzzle allows other kinds of solution than the puzzle linked to. See below.... – Stilez May 28 '18 at 15:59
• Normally King's use animals(rats and verom),prisoners of war, slaves, or etc for this kind of testing. Not people who have years of training, who are hard to replace. I am moving to a new kingdom with a smarter King. – cybernard May 29 '18 at 0:19

Tom's plan is to drink a weak poison before the contest and bring a non-poison to the contest. That way Tom is cured by drinking Bob's strong poison, but Bob dies by drinking only his poison. Bob counters by also bringing a non-poison so that Tom is not cured.

• @PL457 True, but apparently Bob is telepathic and wanted Tom dead. – noedne May 28 '18 at 10:48
• Because Tom is suspicious and doesn't trust Bob, Tom has a backup poison that is even stronger, he can still cure himself. – cybernard May 29 '18 at 0:14

Alternative solution:

Tom offers very foul-tasting, powerful and immediate emetic as his "poison", and brings a poison on a tissue. He plans that both will vomit Bob's poison, and naturally, afterwards, they will want a glass of water before continuing. If necessary he'll suggest it. Tom plans that they both avoid poisoning due to the emetic, but he will manage to wipe the poison from the tissue onto the rim of Bobs glass of water when it's handed to Bob. (Maybe he watched the last act of Hamlet?) At that point Bob's stomach will be empty and he will die, and Tom will have vomited and live. Tom will tell the king he invented a poison that is so powerful that even vomiting doesn't prevent it working. At worst, he figures, Bob rejects the water and lives, but then Tom at least lives too.

However Bob...

Anticipates this and mixes an antiemetic into his poison, so that whatever's down, stays down. But when Bob explains this to the king, over Tom's surprised and still-warm body, ....

The king...

...realises he has no way to know if Bob's poison is especially strong or not, because Tom never actually tested a poison against Bob's, so the test failed in its purpose.