The bottom line: If one is sceptical about aggregative views, where one can be driven by sufficiently many small harms outweighing a smaller number of large harms, one should also be sceptical about longtermism.
My brief summary:
Longtermists generally prefer reducing catastrophic risk to saving lives of people today. This is because, even though you would be reducing probability of harm by a small amount if focusing on catastrophic risk, the expected vastness of the future means more good is done in expectation.
This argument relies on an aggregative view where we should be driven by sufficiently many small harms outweighing a smaller number of large harms. However there are some cases where we might say such decision-making is impermissible e.g. letting a man get run over by a train instead of pulling a lever to save the man but also make lots of people late for work. One argument for why it’s better to save the man from death is the separateness of persons—there is no actual person who experiences the sum of the individual harms of being late—so there can be no aggregate complaint.
The author shows that a range of non-aggregative views (where we are not driven by sufficiently many small harms outweighing fewer large ones), under different treatments of risk, undermine the case for longtermism. These views typically generate extremely weak claims of assistance from future people.
A relevant GPI paper is Longtermism, aggregation, and catastrophic risk by Emma J. Curran.
I briefly summarised it here, also pasted below:
My brief summary:
Longtermists generally prefer reducing catastrophic risk to saving lives of people today. This is because, even though you would be reducing probability of harm by a small amount if focusing on catastrophic risk, the expected vastness of the future means more good is done in expectation.
This argument relies on an aggregative view where we should be driven by sufficiently many small harms outweighing a smaller number of large harms. However there are some cases where we might say such decision-making is impermissible e.g. letting a man get run over by a train instead of pulling a lever to save the man but also make lots of people late for work. One argument for why it’s better to save the man from death is the separateness of persons—there is no actual person who experiences the sum of the individual harms of being late—so there can be no aggregate complaint.
The author shows that a range of non-aggregative views (where we are not driven by sufficiently many small harms outweighing fewer large ones), under different treatments of risk, undermine the case for longtermism. These views typically generate extremely weak claims of assistance from future people.