You are on a plane trying to escape from the island that only contains knights a

Question

You are on a plane trying to escape from the island that only contains knights and knaves. You know knights always speak the truth and knaves always lie. As the cabin door shuts the pilot and the co-pilot walk down the aisle. And you guessed it They are natives of the island!! They stop at your seat and

The pilot says, The co-pilot is a knave.

The co-pilot says, The pilot is a knave.

As they walk away they both turn around and say, Thank you for flying K & K Airlines. What are the pilot and the co-pilot as in are they knights or knaves, one of each? Justify your answer.

Explanation / Answer

Assume the pilot is a knight, then he will always speak the truth. Then, his statement that “The co-pilot is a knave”  is true. That means the co-pilot is a knave.

If co-pilot is a knave, then his statement “The pilot is a knave” must be false. That means the pilot is a knight.

Assume that the pilot is a knave. Then, his statement “The co-pilot is a knave” is false. So, the co-pilot must be a knight.

if the co-pilot is a knight, then his statement “the pilot is a knave” must be true.

Now, suppose that both are knights, then their statements contradicts the fact that they are telling the truth they should always be speaking the truth.

If both are knaves, then as per their statements both of them should be knight but its contradicts the fact that they are knaves.

Hence, one is knight and one is knave.

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