Probabilities
If a set of histories is consistent then probabilities can be assigned to them in a consistent way. We postulate that the probability of history is simply
which obeys the axioms of probability if the histories come from the same (strongly) consistent set.
As an example, this means the probability of " OR " equals the probability of "" plus the probability of "" minus the probability of " AND ", and so forth.
Read more about this topic: Consistent Histories