Claim 4: Given claims 1-3, and that the “some” civilizations described in claims 1-3 are not vanishingly rare (enough to balance out the very high value), the expected value of averting a random extinction event for a technologically advanced civilization is astronomically high.
I think such civilisations are indeed vanishingly rare. The argument you are making is the classical type of argument I used to endorse, but no longer do. As the one Nick Bostrom makes in Existential Risk Prevention as Global Priority (see my post), it is scope sensitive to the astronomical expected value of the future, but scope insensitive to the infinitesimal increase in probability of astronomically valuable worlds, which results in an astronomical cost of moving probability mass from the least valuable worlds to astronomically valuable ones. Consequently, interventions reducing the nearterm risk of human extinction need not be astronomically cost-effective, and I currently do not think they are.
Thanks for the comment, Dan.
I think such civilisations are indeed vanishingly rare. The argument you are making is the classical type of argument I used to endorse, but no longer do. As the one Nick Bostrom makes in Existential Risk Prevention as Global Priority (see my post), it is scope sensitive to the astronomical expected value of the future, but scope insensitive to the infinitesimal increase in probability of astronomically valuable worlds, which results in an astronomical cost of moving probability mass from the least valuable worlds to astronomically valuable ones. Consequently, interventions reducing the nearterm risk of human extinction need not be astronomically cost-effective, and I currently do not think they are.