Thanks for writing—I skimmed so may have missed things, but I think these arguments have significant weaknesses, e.g.:
They draw a strong conclusion about major historical patterns just based on guesswork about ~12 examples (including 3 that are explicitly taken from the author’s imagination).
They do not consider examples which suggest long-term thinking has been very beneficial.
E.g. some sources suggest that Lincoln had long-term motivations for permanently abolishing slavery, saying, “The abolition of slavery by constitutional provision settles the fate, for all coming time, not only of the millions now in bondage, but of unborn millions to come—a measure of such importance that these two votes must be procured.”
As another comment suggests, the argument does not consider ways in which our time might be different (e.g. unusually many people are trying to have long-term impacts, people are less ignorant, tech advances may create rare opportunities for long-term impact).
Good points!
Agreed that this wouldn’t make much of a difference for donations, although maybe it matters a lot for some career decisions. E.g. if future people weren’t ethically important, then there might be little value in starting a 4+ year academic degree to then donate to these charities.
(Tangentially, the time inconsistency of presentists’ preferences seems pretty inconvenient for career planning.)