Question: Do you believe that all ducks are grey? Many students claim that they have seen white ducks, but proves that all ducks are grey. Remember, a correct proof compels assent-so either you believe a correct proof or you believe that the given proof is problematic. Try to find an error in the proof, or justify completely that all ducks are grey. (Okay, this isn't really a problem to solve, so much as some questions to think about.) Do not try looking this up (e.g., on the internet). That would spoil your fun! Instead, think through the details of the proof. Does the base case make sense? Is the inducktive hypothesis correctly stated? How does the inductive step hold up under scrutiny?