A very special island is inhabited only by knights and knaves. Knights always tell the truth, and knaves always lie. You meet 6 inhabitants: Victoria, Grace, Jackson, Liam, Henry, and Joseph. "Liam is not a knave," Victoria claimed. Grace noted, "If Henry is a knight then Victoria is a knight". Jackson asserted: "If Victoria is a knave then Henry is a knave". Liam said, "Joseph is a knight." "Jackson is not a knight," Henry claimed. Joseph said that Liam is a knave or Grace is a knight. So who is a knight and who is a knave?
Victoria is a knight, Grace is a knight, Jackson is a knight, Liam is a knight, Henry is a knave, and Joseph is a knight.
(1) Victoria is a knight
(2) Grace is a knight
(3) Jackson is a knight
(4) Liam is a knight
(5) Henry is a knave
(6) Joseph is a knight
Assume Victoria is a knight. No contradiction is found in their claim that Liam is not a knave. Assume Liam is a knight. No contradiction is found in their claim that Joseph is a knight. Assume Joseph is a knight. No contradiction is found in their claim that Liam is a knave or Grace is a knight. Assume Grace is a knight. No contradiction is found in their claim that If Henry is a knight then Victoria is a knight. Assume Henry is a knight. No contradiction is found in their claim that Jackson is not a knight. Jackson cannot be a knight, because this would contradict the claim of Henry that Jackson is not a knight. Jackson cannot be a knave, because this would contradict the false claim of their own that If Victoria is a knave then Henry is a knave. We have exhausted all possibilities for Jackson, so let us go back and reconsider Henry. Assume Henry is a knave. No contradiction is found in their false claim that Jackson is not a knight. Assume Jackson is a knight. No contradiction is found in their claim that If Victoria is a knave then Henry is a knave.