Is the argument that eventual extinction makes immediate concerns irrelevant? If so, that is pure balderdash. Immediate concerns are always concerning.

If the argument is that extinction is inevitable, so it is pointless to do anything to combat global warming or any other existential threat, then it seems to me, given that immediate concerns are always concerning, that the argument turns on practical possibilities of success, not meaninglessness as a cosmological imperative.

If the argument is that all previous attempts at attributing meaning (as ‘value’) to human life have been matters of personal belief, and not anything every human being can be required to accept absent coercion of some kind (thereby bringing the reflexivity problem into it), I would agree. For that I have a response: real justice.

The ethic of real justice is mutual respect in effecting choices. [Warren J. Samuels all but defined “social power” as the ability to effect choices, i.e. choose among perceived alternatives and take action towards bringing that choice to fruition.] Human beings have no choice but to effect choices.

This ethic thereby follows from observation within material existence. It requires human beings to recognize other humans who are involved whenever anyone is effecting a choice by taking them into account. At a minimum, all people must refrain from, borrowing from Locke, “subjecting” any other person(s) to one’s own “arbitrary will” in the process of effecting any choice.

Since its determiners and its referents are contained within material existence, the ethic of real justice is as ‘real’ as any other part of that existence. That legitimately de-legitimates going outside material existence (to beliefs) to justify violating the ethic. Any human being can still violate the ethic, but no choice-effecting human being co-existing with other human beings can deny the applicability of this ethic to all human beings, including oneself. That establishes ethical value, thus ‘meaning’, for every human existence.