eli5 When it comes to probabilities of past events

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When someone says “wow there was only a 30% chance of that happening!” But wouldn’t it be 100% because it DID happen and due to an (probably) infinite amount of unseen variables? In this way would this mean the universe is deterministic?

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Anonymous 0 Comments

>“wow there was only a 30% chance of that happening!”

The operative word here is “WAS”. Yes now that it has happened, there is a 100% chance that that’s the outcome that happened. But before that, there WAS a 30% chance that that outcome would be the one that happened. When people say “there was only a [%] chance of that happening”, they mean that’s what the probability was before the event happened, given only the information available at the time.

If you flip a coin and get heads, there *was* a 50% chance of that happening – because before the flip, the odds of heads *was* 50%.

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