How to solve Knights and Knaves
Knights always tell the truth. Knaves always lie. List every case and cross out the ones that contradict themselves.
A says: “We are both knaves.”
| A | B |
|---|---|
| Knight | Knight |
| Knight | Knave |
| Knave | Knight |
| Knave | Knave |
1 of 4
How it works
Every islander is a knight or a knave. A knight’s statement is true; a knave’s statement is false. Your job is to work out who is which.
The reliable method is case analysis: write down every combination, then test each one. A row survives only if every knight said something true and every knave said something false.
Worth memorizing
A knight’s statement is true. A knave’s is false.
Nobody can say “I am a knave.”
It is a contradiction either way: a knight would be lying and a knave would be telling the truth.
List every case, then cross out.
Two islanders means four rows. Three means eight.
Practice
0 of 3 rightQuestion 1
- A says: “B is a knave.”
- B says: “A and I are the same kind.”
Question 2
- A says: “At least one of us is a knave.”
Question 3
- A says: “B is a knight.”
- B says: “A and I are different kinds.”