These are some initial reflections written quickly mostly to elicit discussions (before potentially diving more into the topic).

Abstract/Introduction

Longtermists aim to have an overall positive impact on the long-term future, which requires them to form beliefs about what actions would do more good than harm in this regard. One could question the reliability of such beliefs by defending the following evolutionary argument for cluelessness:

P1: One’s beliefs about what actions positively influence the long-term future (in expectation) decisively rely on judgment calls (by which I mean intuitions that are neither clearly supported nor clearly undermined by the available evidence).
P2: There has been no evolutionary pressure (not even indirect) against individuals unable to make the correct judgment calls regarding what actions do more good than harm (in expectation) considering their far future effects.
Conclusion: Having non-agnostic beliefs about what actions longtermism recommends is unwarranted.

Assuming no misunderstanding of what I mean, I expect everyone to agree the conclusion logically follows from these two premises.^[1] However, I expect skepticism towards P1 and especially P2 and am interested in people giving me compelling objections to these in the comments. My aim in the rest of the post is to help commenters do this by first addressing objections that I think are bad or unconvincing if not accompanied by further justification that I couldn't (yet) really come up with.

Objections to P1

Recall P1: One’s beliefs about what actions positively influence the long-term future (in expectation) decisively rely on judgment calls (by which I mean intuitions that are neither clearly supported nor clearly undermined by the available evidence).

“Surely there’s at least the longtermist argument for X-risk reduction that is robustly justified without judgment call.”

Here’s a list of crucial factors you have to consider while assessing whether X-risk reduction is good from a (full)^[2] longtermist perspective:

what is (dis)valuable and what kind of value ethically compensates for what kind of disvalue
what animals are moral subjects and to what extent
whether and/or when humanity will stop farming (some of) the animals with miserable lives we would not wish to live
whether we will spread wildlife to other celestial bodies and how much
the

...

On Cluelessness