Andreas Mogensen, a Senior Research Fellow at the Global Priorities Institute, has just published a draft of a paper on "Maximal Cluelessness". Abstract:
I argue that many of the priority rankings that have been proposed by effective altruists seem to be in tension with apparently reasonable assumptions about the rational pursuit of our aims in the face of uncertainty. The particular issue on which I focus arises from recognition of the overwhelming importance and inscrutability of the indirect effects of our actions, conjoined with the plausibility of a permissive decision principle governing cases of deep uncertainty, known as the maximality rule. I conclude that we lack a compelling decision theory that is consistent with a long-termist perspective and does not downplay the depth of our uncertainty while supporting orthodox effective altruist conclusions about cause prioritization.
My belief that cluelessness is important is fairly independent of any specific philosophical/technical account of cluelessness. In particular, I don't think me changing my mind on whether credence functions have to be sharp would significantly change my views on the importance of cluelessness.
In this comment I've explained in more detail what I think about the relationship between the basic idea and specific philosophical theories trying to describe it.
(FWIW, I don't feel like I have a well-informed view on whether credence functions have to be sharp. If anything, I have a weak intuition that it's a bit more likely than not that I'd conclude they have to be if I spent more time looking into the question.)