A very special island is inhabited only by knights and knaves. Knights always tell the truth, and knaves always lie. You meet 6 inhabitants: James, Samuel, Henry, Mason, Aria, and William. In James's words: "Aria is a knight". Samuel was heard saying, "Mason is a knave and Henry is a knave". "William is a knave if and only if Aria is a knight," Henry mentioned. According to Mason, "Aria is a knight". In Aria's words: "Aria is a knight or William is a knight". According to William, "Mason is a knave or Aria is a knight". So who is a knight and who is a knave?
James is a knight, Samuel is a knave, Henry is a knave, Mason is a knight, Aria is a knight, and William is a knight.
(1) James is a knight
(2) Samuel is a knave
(3) Henry is a knave
(4) Mason is a knight
(5) Aria is a knight
(6) William is a knight
Assume James is a knight. No contradiction is found in their claim that Aria is a knight. Assume Aria is a knight. No contradiction is found in their claim that Aria is a knight or William is a knight. Assume William is a knight. No contradiction is found in their claim that Mason is a knave or Aria is a knight. Assume Mason is a knight. No contradiction is found in their claim that Aria is a knight. Samuel cannot be a knight, because this would contradict the claim of their own that Mason is a knave and Henry is a knave. Assume Samuel is a knave. No contradiction is found in their false claim that Mason is a knave and Henry is a knave. Henry cannot be a knight, because this would contradict the claim of their own that William is a knave if and only if Aria is a knight. Assume Henry is a knave. No contradiction is found in their false claim that William is a knave if and only if Aria is a knight.