Basically I think the idea is that because of inevitable uncertainty, there will be multiple activists/option/donations that may all be considered “the best”, or at least among which it is not possible to draw a comparison.
I think this is true even if all moral outcomes are comparable, but of course if not then it follows that all activities are probably not comparable either.
The most good you can do is a Schwartz Set.
Basically I think the idea is that because of inevitable uncertainty, there will be multiple activists/option/donations that may all be considered “the best”, or at least among which it is not possible to draw a comparison.
I think this is true even if all moral outcomes are comparable, but of course if not then it follows that all activities are probably not comparable either.