The Three Doors Problem, or Monty Hall Problem, is familiar to statisticians as a paradox in elementary probability theory often found in elementary probability texts (especially in their exercises sections). In that context it is usually meant to be solved by careful (and elementary) application of Bayes’ theorem. However, in different forms, it is much discussed and argued about and written about by psychologists, game-theorists and mathematical economists, educationalists, journalists, lay persons, blog-writers, wikipedia editors.