From Symbolic Logic: Part 1, Elementary. Born Charles Dodgson in 1832, Carroll became a lecturer in mathematics at Oxford University in 1855, published his first book, on geometry, in 1860, and told the story of a girl falling down a rabbit hole to ten-year-old Alice Liddell at a picnic in 1862. “Oh, Mr. Dodgson,” she said, “I wish you would write out Alice’s adventures for me!” He published Alice’s Adventures in Wonderland in 1865 and Through the Looking-Glass in 1871. Much of the second volume of his symbolic logic already had been set in type when he died in 1898.
1. Babies are illogical;
2. Nobody is despised who can manage a crocodile;
3. Illogical persons are despised.
Answer: Babies cannot manage crocodiles.
1. There are no Jews in the kitchen;
2. No Gentiles say “shpoonj”;
3. My servants are all in the kitchen.
Answer: My servants never say “shpoonj.”
1. No ducks waltz;
2. No officers ever decline to waltz;
3. All my poultry are ducks.
Answer: My poultry are not officers.
1. No one takes in the Times unless he is well-educated;
2. No hedgehogs can read;
3. Those who cannot read are not well-educated.
Answer: No hedgehog takes in the Times.
1. All the MPs who belong to the House of Commons have perfect self-command;
2. No MP who wears a coronet should ride in a donkey race;
3. All the MPs who belong to the House of Lords wear coronets.
Answer: No MP should ride in a donkey race unless he has perfect self-command.
1. Nobody who really appreciates Beethoven fails to keep silence while the “Moonlight Sonata” is being played;
2. Guinea pigs are hopelessly ignorant of music;
3. No one who is hopelessly ignorant of music ever keeps silence while the “Moonlight Sonata” is being played.
Answer: Guinea pigs never really appreciate Beethoven.
1. No interesting poems are unpopular among people of real taste;
2. No modern poetry is free from affectation;
3. All your poems are on the subject of soap bubbles;
4. No affected poetry is popular among people of real taste;
5. No ancient poem is on the subject of soap bubbles.
Answer: All your poems are uninteresting.
The Triumph of Ridicule, by Basset, 1773. De Agostini Picture Library, G. Dagli Orti, The Bridgeman Art Library.
1. There is no box of mine in this room that I dare open;
2. My writing desk is made of rosewood;
3. All my boxes are painted, except those in this room;
4. There is no box of mine that I dare not open, unless it is full of live scorpions;
5. All my rosewood boxes are unpainted.
Answer: My writing desk is full of live scorpions.
1. All writers who understand human nature are clever;
2. No one is a true poet unless he can stir the hearts of men;
3. Shakespeare wrote Hamlet;
4. Not but those who understand human nature can stir the hearts of men;
5. None but a true poet could have written Hamlet.
Answer: Shakespeare was clever.
1. Animals that do not kick are always unexcitable;
2. Donkeys have no horns;
3. A buffalo can always toss one over a gate;
4. No animals that kick are easy to swallow;
5. No hornless animal can toss one over a gate;
6. All animals are excitable, except buffalo.
Answer: Donkeys are not easy to swallow.
1. Animals are always mortally offended if I fail to notice them;
2. The only animals that belong to me are in that field;
3. No animal can guess a conundrum unless it has been properly trained in a board school;
4. None of the animals in that field are badgers;
5. When an animal is mortally offended, it rushes about wildly and howls;
6. I never notice any animal unless it belongs to me;
7. No animal that has been properly trained in a board school ever rushes about wildly and howls.
Answer: No badger can guess a conundrum.
Friar Pedro Shoots El Maragato as His Horse Runs Off, by Francisco José de Goya y Lucientes, c. 1806. Art Institute of Chicago, Mr. and Mrs. Martin A. Ryerson Collection.
1. The only animals in this house are cats;
2. Any animal is suitable for a pet if it loves to gaze at the moon;
3. When I detest an animal, I avoid it;
4. No animals are carnivorous, unless they prowl at night;
5. No cat fails to kill mice;
6. No animals ever take to me, except what are in this house;
7. Kangaroos are not suitable for pets;
8. None but carnivores kill mice;
9. I detest an animal that does not take to me;
10. Animals that prowl at night always love to gaze at the moon.
Answer: I always avoid a kangaroo.