---
title: Knights and Knaves Puzzles
---
## Knights and Knaves

One type of logic puzzle, these puzzles have to do with two types of people. Knights: people who only tell the truth and Knaves: people who only tell lies. Raymond Smullyan collected dozens of puzzles like this in his book, "What is the Name of This Book?". 
The way the puzzles work is that a person visits an island where he meets an inhabitant or group. The visitor must use his logic skills to figure out who is the knight and who is the knave. 

## Sample Puzzles

### Red and Blue

Two people, Red and Blue, stand before you. Red says, “We are both knaves.” What are they really? 

**Solution:** Red cannot be a knight, because then he would be lying by saying he is a knave. Therefore he is a knave, and his statement is a lie, meaning that Blue must be a knight.

### Which Path to Take?

You come to a fork in a road and need to learn which path leads to your destination. Two individuals are standing there. You know that one is a knight and one is a knave, but you don’t know which is which. What single yes-or-no question could you ask of one of the islanders to learn the correct path?

**Solution:** Point to a path and ask of one, “Would the other one tell me that this is the correct path?” If the answer is No, that is the correct path; if Yes, it is the incorrect path.

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#### More Information:
* <a href='https://www.amazon.com/gp/product/0486481980/ref=as_li_qf_sp_asin_il_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=0486481980&linkCode=as2&tag=brenconl05-20&linkId=UU6GFKPWEKZFK2XG' target='_blank' rel='nofollow'>What is the Name of This Book? from Amazon</a>
* <a href='https://en.wikipedia.org/wiki/Knights_and_Knaves' target='_blank' rel='nofollow'>Wikipedia Article</a>


