The factually incorrect part is the hidden premise that "convinced that X has never happened" is equivalent to "assigns P(x) = 0". In fact, it is equivalent to

The factually incorrect part is the hidden premise that "convinced that X has never happened" is equivalent to "assigns P(x) = 0". In fact, it is equivalent to "assigns P(x) = epsilon", where the number of possible sequences is several orders of magnitude greater than 1/epsilon. It basically comes down to saying something like this: 1. 1/x ≈ 0 for very large x 2. x0 = 0 for all x 3. So x1/x ≈ 0 for very large x 4. But x/x = 1 Therefore 1 ≈ 0 This reasoning is correct, but the error tucked away in that last "≈" is exactly 1.