knights and knaves

• 
  There are three people (Alex, Brook and Cody), one of whom is a knight, one a knave, and one a spy.
  
  The knight always tells the truth, the knave always lies, and the spy can either lie or tell the truth.
  Alex says: "Cody is a knave."
  Brook says: "Alex is a knight."
  Cody says: "I am the spy."
  
  Who is the knight, who the knave, and who the spy?
  
• 9 years agoHelpfull: Yes(5) No(0)
• Alex is a Knight
  Brook is a Spy
  Cody is a Knave
  
  Brook is not the knight, since if he is, then Alex would also be the knight.
  Cody is not the knight, since his statement would then be a lie.
  
  Therefore Alex is the knight. Hence Cody is the knave, and Brook is the spy.
• 9 years agoHelpfull: Yes(5) No(0)