What can you conclude from the following three premisses?
- If something is not gift-wrapped, it's not a gift.
- Nothing that's gift-wrapped is entirely unlike a box of chocolates.
- Life is a gift.
Lewis Carroll published a book of about a hundred puzzles like this one. Read it online: introduction; puzzles. My nephew IM and I stumbled upon them in Memphis last week. He pretty much knocked them out of the park one at a time.
They're fairly easy to make, if you know some logic and some algebra. Here are a few more (but Lewis Carroll's are the most sublime nonsense—you should probably try those instead.)
- Anyone lacking impeccable fashion sense might wear a rhinestone sombrero.
- Anyone who might wear a rhinestone sombrero can't dance.
- All penguins can dance.
- Animals that are active during the day are either featherless or tasty—or both.
- No creature is both nocturnal and naturally funny.
- Chickens have feathers.
- Chickens are naturally funny.
Concerning the inhabitants of this town
- All the monsters in this town are carnivores.
- A carnivore would eat anything made of meat.
- No creature in this town would eat any other creature in this town.
- Humans are made of meat.
- Only monsters can make the ground tremble.
- Two-year-olds and raccoons get into everything (two-year-old raccoons doubly so).
- If something gets into everything, but it doesn't emit terrifying shrieks, it must be a raccoon.
- All firebreathing creatures are monsters.
- Opera singers can make the ground tremble.
- Raccoons are not human.
- A creature that isn't a monster doesn't have slavering fangs.
- If a creature emits terrifying shrieks, then either it breathes fire, it has slavering fangs, or it's an opera singer.