A very special island is inhabited only by knights and knaves. Knights always tell the truth, and knaves always lie. You meet 6 inhabitants: Aria, Mason, Henry, Benjamin, Abigail, and Charlotte. As Aria put it, "Mason is a knight". Mason expressed that Aria is a knave and Charlotte is a knave. "Charlotte is not a knight," Henry claimed. Benjamin noted, "Aria is a knave if and only if Mason is a knave". Abigail commented, "Benjamin is a knight". Charlotte noted, "Charlotte is a knight or Henry is a knave". So who is a knight and who is a knave?
Aria is a knave, Mason is a knave, Henry is a knave, Benjamin is a knight, Abigail is a knight, and Charlotte is a knight.
(1) Aria is a knave
(2) Mason is a knave
(3) Henry is a knave
(4) Benjamin is a knight
(5) Abigail is a knight
(6) Charlotte is a knight
Assume Aria is a knight. No contradiction is found in their claim that Mason is a knight. Mason cannot be a knight, because this would contradict the claim of their own that Aria is a knave and Charlotte is a knave. Mason cannot be a knave, because this would contradict the claim of Aria that Mason is a knight. We have exhausted all possibilities for Mason, so let us go back and reconsider Aria. Assume Aria is a knave. No contradiction is found in their false claim that Mason is a knight. Mason cannot be a knight, because this would contradict the false claim of Aria that Mason is a knight. Assume Mason is a knave. No contradiction is found in their false claim that Aria is a knave and Charlotte is a knave. Assume Charlotte is a knight. No contradiction is found in their claim that Charlotte is a knight or Henry is a knave. Henry cannot be a knight, because this would contradict the claim of their own that Charlotte is not a knight. Assume Henry is a knave. No contradiction is found in their false claim that Charlotte is not a knight. Assume Benjamin is a knight. No contradiction is found in their claim that Aria is a knave if and only if Mason is a knave. Assume Abigail is a knight. No contradiction is found in their claim that Benjamin is a knight.