Earlier today I set you the following three puzzles.
1. Late Wittgenstein
Wittgenstein has been murdered. The culprit is one of either Friedrich Nietzsche, Lou Andreas-Salomé, Karl Marx or Ludwig Feuerbach. They make the following statements. You have been correctly informed that guilty person always lies, and everyone else tells the truth.
Nietzsche: Salomé is the culprit.
Salomé: Marx is innocent.
Feuerbach: Salomé’s statement is true.
Marx: Nietzsche’s statement is false.
Who killed Wittgenstein?
If Nietzsche is telling the truth, then Salomé is the culprit and therefore a liar. Thus Marx is not innocent, meaning he is the culprit. We can’t have two culprits, since this is forbidden in the setting of the question, and so we are led to contradiction. Nietzsche must therefore be lying. If he is lying, then everyone else tells the truth, which they can without contradiction. Thus Nietzsche killed