There will, eventually, be an end to the human race. We don’t think enough about the significance of this fact.

I am not even talking about avoidable apocalypses, as real as the threat of those is. I am assuming for the sake of argument that we will manage to avoid being stupid enough to kill ourselves off in the next few centuries, through global nuclear war or climate change or AI robots or nanotechnology or a newly emerging plague. Many if not all of those are real threats and we should do whatever we can to prevent them from destroying us. But for my purposes here I’m assuming we’re smart enough to fend them off. The point is that humanity will end even so. It may take a very, very long time. But it will happen.

Even with all our technological ability to adapt, we are still dependent on a relatively fragile biosphere. A comet or nearby supernova could cause kill us off in a mass extinction event of the sort that got the dinosaurs. Even if we survive that, eventually the sun’s radiation will increase enough for plant life, and therefore all the species that depend on plants directly or indirectly, to go extinct. Beyond that, the oceans will evaporate and the climate will get as hot as Venus’s, no longer suitable for human life.

That’s millions or even a billion years in the future. By that point we may well have developed interstellar travel and the ability to colonize other planets. But then there will be events changing the very fabric of the universe – most likely the heat death of the universe, where the universe’s expansion continue to bring its temperatures toward absolute zero. Theories about these sorts of events are still relatively speculative – there are other ultimate fates speculated on for the universe, a “Big Rip” or “Big Crunch” – but we have no reason to believe that the current state of the physical universe is forever, and our existence depends on that current state. Our entire species is mere biology in a world of physics; at some point, inevitably, that species will cease to be biology and return to physics, and then our human existence will be no more. “Dust In The Wind” didn’t go far enough: at some point even the earth and sky, as we know them, will cease to be.

Now for immediate practical purposes, the sort of things we can plan for, none of this really matters a whole lot. We need to prevent the preventable apocalypses and maybe start thinking about eventual interstellar travel; in terms of what we can do, that’s good enough. But there is also a realm in which the inevitability of human extinction matters a great deal, and that is in our thinking about the meaning and purpose of human life. Because far too often, we think about that meaning and purpose in ways that effectively assume humanity will go on forever. And that is a deeply misguided approach.

Especially, human extinction strikes at the heart of any prophetic view of humanity’s ultimate purpose – whether theistic or secularized. It strikes deeply at Simone Weil’s claim that “Atheist materialism is necessarily revolutionary, because to orient oneself toward an absolute good down here, one must place it in the future.” When we recognize human extinction, we see that there will be no absolute good in the future, and cannot be. There will be relative goods: we can make our species’s future much better for millions of years, and it’s well worth trying. But that better future society cannot be the absolute good, the ultimate purpose of human life – not when it too will end. Just as we must develop our individual ethics with the recognition that individually we will each one day die, so too we must develop our politics and theory of history with the recognition that collectively, too, we as a species will die out. The fate of our species – and of every other species that depends on its fragile biology – is the fate of the individual writ large.

Thus it is folly to accept the revolutionary conception of the absolute good that, Weil claims, follows from atheist materialism. If Weil is right, atheist materialism is wrong. It’s quite reasonable to say that she isn’t right – that one can have an atheist materialism that doesn’t require an “absolute good down here”, or even that there is some absolute good down here that is not in the revolutionary future. But any reasonable cosmological understanding must tell us that the revolutionary future is not absolute. Even if we ever did produce a true utopia – which, given everything we know about how humans act in the world, seems extremely unlikely – it too will ultimately cease to be. That is the Lovecraftian reality underneath the universe, the actual lurking horror about which Kepler was right to panic, even if it’s able to continue to lurk for millions of years.

But is not just revolutionary atheist materialism for which humanity’s end poses a difficulty. Martin Luther King’s faith famously led him to proclaim that “the arc of the moral universe is long, but it bends toward justice.” But in its longer arc, the universe is amoral: once upon a time there were no moral beings, and someday, whatever justice has been achieved for the beings who remain, they too will be wiped away.

Luke 1 says of Jesus, “the Lord God shall give unto him the throne of his father David: And he shall reign over the house of Jacob for ever; and of his kingdom there shall be no end.” We know now that this cannot be true, if any such kingdom were supposed to exist in the physical or material world. “His kingdom shall have no end” can only be true if it also had no beginning – if the kingdom is outside of time, outside nature itself. What it cannot correctly imply is a prophecy that there will be an endless godly kingdom here on earth. Such a view is implied in Richard Swinburne’s deeply problematic response to the problem of suffering: that the universe is “half-finished”, “such that it requires long generations of cooperative effort between creatures to make perfect.” Even if we thought that the great present suffering around us could be theologically justified by the need for our work in “making it perfect”, it turns out we can’t do that. We can’t make our utopia last – and if it doesn’t last, it’s not perfect. It’s certainly not going to justify all the children who had to die in fires and plagues along the way to get us there.

So too, if we seek to enrich humanity with our creations – artistic or scientific or philosophical or whatever – we must remember that while these can outlast us individually, they won’t outlast the species. With human extinction, there will be no one left to appreciate Shakespeare or Aśvaghoṣa, let alone the lesser works produced by the rest of us. The glory of Valmiki or Plato has lasted thousands of years longer than their own tiny lifespans did, but that glory itself is not immortal.

All of this probably sounds depressing, and it is depressing to anyone who has imagined their own purpose in life as building a permanent future utopia or writing immortal works. (I have not been immune to that way of thinking.) But the thought of one’s own individual death can be depressing in a similar way, and most of philosophy begins with a recognition of that constraint: we can and should live good lives that recognize we must eventually die. So what can we do to live good lives while recognizing that the world must eventually die? More on that question next time.