Do you agree that the probability of an event depends on your knowledge? For example, what is the probability that the bottom card of a shuffled deck is an ace? Peek at the top card, it's an ace of spades, now what is the probability?
Would you agree that something is determined iff its probability is zero or one? I'm guessing the disagreement is here - what definition would you use?
Would you agree that something is determined iff its probability is zero or one? I'm guessing the disagreement is here - what definition would you use?