A very special island is inhabited only by knights and knaves. Knights always tell the truth, and knaves always lie. You meet 6 inhabitants: Mason, Harper, Chloe, Oliver, Lucas, and William. "Mason is a knight and William is a knight" - Mason. Harper asserted: "Harper is a knight and William is a knight". Chloe stated, "Lucas is a knave or William is a knight". Oliver told you that William is a knave or William is a knight. In a statement by Lucas: "If Harper is a knave then Oliver is a knight". William asserted: "Mason is a knave and Harper is a knave". So who is a knight and who is a knave?
Mason is a knave, Harper is a knave, Chloe is a knight, Oliver is a knight, Lucas is a knight, and William is a knight.
(1) Mason is a knave
(2) Harper is a knave
(3) Chloe is a knight
(4) Oliver is a knight
(5) Lucas is a knight
(6) William is a knight
Assume Mason is a knight. No contradiction is found in their claim that Mason is a knight and William is a knight. William cannot be a knight, because this would contradict the claim of their own that Mason is a knave and Harper is a knave. William cannot be a knave, because this would contradict the claim of Mason that Mason is a knight and William is a knight. We have exhausted all possibilities for William, so let us go back and reconsider Mason. Assume Mason is a knave. No contradiction is found in their false claim that Mason is a knight and William is a knight. Assume William is a knight. No contradiction is found in their claim that Mason is a knave and Harper is a knave. Harper cannot be a knight, because this would contradict the claim of William that Mason is a knave and Harper is a knave. Assume Harper is a knave. No contradiction is found in their false claim that Harper is a knight and William is a knight. Assume Chloe is a knight. No contradiction is found in their claim that Lucas is a knave or William is a knight. Assume Lucas is a knight. No contradiction is found in their claim that If Harper is a knave then Oliver is a knight. Assume Oliver is a knight. No contradiction is found in their claim that William is a knave or William is a knight.