Puzzler of the Day
This is one of many "knights and knaves" puzzles, which were created by mathematician Raymond Smullyan.
The setting for most such puzzles is on an island which is
inhabited by two types of people, knights and knaves. Knights always
tell the truth and knaves always lie.
A visitor to the island encounters two inhabitants, A and B.
A says: We are both knaves (that is, A and B are both knaves).
Question: What are A and B? Knight or knave?