no this is not about the meaning of words its about mathematical probabilities
if every eventuality has a probability of happening X and a probability of not happening Y
(P) X + Y = 1 (it will either happen or it wont)
but its the equation itself that poses the question
what is the (P) X + Y not= 1 (the answer shud be 0)
but as everything has a probability above 0 this cannot be mathematicaly true