Mark Johnston in the Boston Review:
Who knows what form the end of humanity will take? Will it come by extraterrestrial invasion, or by the erosion of the ozone layer, or by a large asteroid impacting the earth, or by mass starvation during a long nuclear winter, or by a bacterium running amok in the post-antibiotic age, or by a nomadic black hole sucking up everything in its path as it wanders toward us, or by a gamma ray burst from any one of the host of supernovas destined to occur within three thousand light years of the earth, or by the eruption of the massive volcano that now sits, waiting, under Yellowstone National Park? Or will it be as the apocalyptic literature of Judaism and Christianity describes it, with the last days consisting of the terrifying separation of the sheep from the goats? Even if humanity somehow avoids all this, and even if we escape the solar system before the inevitable heat death of the sun, eventually the universe will come to consist of a subatomic soup so thin that nothing recognizably human will be able to exist.
So we are doomed. There is no way around it. The hope is that doom is far enough away for humanity to flourish individually and collectively. The lights will eventually go out; the issue is just how brightly they will burn in the interim.
Here ignorance is not exactly bliss, but it is helpful. Unless you are professionally involved in existential risk assessment or in one of those fields, such as bio-warfare, where the resultant blowback could indeed wipe us out, it is wise to forget about our inevitable collective obliteration precisely because of its capacity to uselessly demoralize us. When it comes to the end of humanity, Spinoza’s advice to individuals concerning their own deaths seems even more pertinent: “A free man thinks of nothing less than of death, and his wisdom is a meditation not on death, but on life.”
But what if, as a brute psychological matter, we just cannot put the end of humanity out of our minds? There are two quite different cases in which the thought of our collective end might worry us: the case where we are demoralized because we really are, or take ourselves to be, in the last days, and the case where we are demoralized merely by the fact that there will be a last day.