Tho' there be no such Thing as Chance in the World; our Ignorance of the real Ccause of any Event has the same Influence on the Understanding, and begets a like Species of Belief or Opinion.
Finally, we might decide that civilisation itself is worth preserving. In that case we have to work out what to save and which people would be needed in a drastically reduced population - weighing the value of scientists and musicians against that of politicians, for example. . .