  We analyze the main arguments that attempt to explain why there is no point
in changing the envelope. Most people confuse estimation and calculation,
conditional and unconditional probabilities, random and non-random variables,
modelling and reality, chance and uncertainty (or credence), whatever X known
and whatever X unknown, personal and interpersonal estimates. Such confusions
suggest that there would be no point in swapping the envelope. Our analysis is
that if the first envelope is opened, whatever the amount, it is rational and
consistent to think that it is worth changing it. If the first envelope is not
opened, it is rational and consistent to believe there is no point in swapping
the envelope.

History and Overview;Probability