I think you’d want to modify that to preventable x-risk, to get Will to agree; and also to add a third part of the disjunction, that preventing x-risk might not be of overriding moral importance (since he raises the possibility that longtermism is false in a comment below, with the implication that if so, even preventing x-risk wouldn’t make us “influential” by his standards).
However, if Will thinks his argument as currently phrased holds, then it seems to me that he’s forced to agree with similar arguments that use slightly different definitions of influentialness (such as influentialness = the expected amount you can change other people’s lives, for better or worse). Or even a similar argument which just tries to calculate directly the probability that we’re at the time with the most x-risk, rather than talking about influentialness at all. At that point, the selection effect I described in another comment starts to become a concern.
I think you’d want to modify that to preventable x-risk, to get Will to agree; and also to add a third part of the disjunction, that preventing x-risk might not be of overriding moral importance (since he raises the possibility that longtermism is false in a comment below, with the implication that if so, even preventing x-risk wouldn’t make us “influential” by his standards).
However, if Will thinks his argument as currently phrased holds, then it seems to me that he’s forced to agree with similar arguments that use slightly different definitions of influentialness (such as influentialness = the expected amount you can change other people’s lives, for better or worse). Or even a similar argument which just tries to calculate directly the probability that we’re at the time with the most x-risk, rather than talking about influentialness at all. At that point, the selection effect I described in another comment starts to become a concern.