The only point of probabilities is to have them guide actions.
I don’t agree with that (a quick example is that speculating about the Big Bang is entirely pointless under this approach), but that’s a separate discussion.
How does the concept of Knightian uncertainty help in guiding actions?
It allows you to not invent fake probabilities and suffer from believing you have a handle on something when in reality you don’t.
OK, I’ll give you that we might non-instrumentally value the accuracy of our beliefs (even so, I don’t know how unpack ‘accuracy’ in a way that can handle both probabilities and uncertainty, but I agree this is another discussion). I still suspect that the concept of uncertainty doesn’t help with instrumental rationality, bracketing the supposed immorality of assigning probabilities from sparse information. (Recall that you claimed Knightian uncertainty was ‘useful’.)
I don’t agree with that (a quick example is that speculating about the Big Bang is entirely pointless under this approach), but that’s a separate discussion.
It allows you to not invent fake probabilities and suffer from believing you have a handle on something when in reality you don’t.
Such speculation may help guide actions regarding future investments in telescopes, decisions on whether to try to look for aliens, etc.
OK, I’ll give you that we might non-instrumentally value the accuracy of our beliefs (even so, I don’t know how unpack ‘accuracy’ in a way that can handle both probabilities and uncertainty, but I agree this is another discussion). I still suspect that the concept of uncertainty doesn’t help with instrumental rationality, bracketing the supposed immorality of assigning probabilities from sparse information. (Recall that you claimed Knightian uncertainty was ‘useful’.)