as mentioned above, "any distribution" producing this variant of the paradox must have an infinite mean. so before the player opens an envelope the expected gain from switching is "∞ − ∞", which is not defined. in the words of david chalmers (2002), this is "just another example of a familiar phenomenon, the strange behaviour of infinity". chalmers suggests that decision theory generally breaks down when confronted with games having a diverging expectation, and compares it with the situation generated by the classical st. petersburg paradox.