Random or uncertain?

By  via andrewgelman.com   Article

What’s the difference between randomness and uncertainty?

“Julia Galef mentioned ‘meta-uncertainty,’ and how to characterize the difference between a 50% credence about a coin flip coming up heads, vs. a 50% credence about something like advanced AI being invented this century.

I wrote: Yes, I’ve written about this probability thing. The way to distinguish these two scenarios is to embed each of them in a larger setting. The question is, how would each probability change as additional information becomes available. The coin flip is ‘random’ to the extent that intermediate information is not available that would change the probability. Indeed, the flip becomes less ‘random’ to the extent that it is flipped. In other settings such as the outcome of an uncertain sports competition, intermediate information could be available (for example, maybe some key participants are sick or injured) hence it makes sense to speak of ‘uncertainty’ as well as randomness.

It’s an interesting example because people have sometimes considered this to be merely a question of ‘philosophy’ or interpretation, but the distinction between different sources of uncertainty can in fact be encoded in the mathematics of conditional probability.”

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