Intro/summary:
Will MacAskill, arguably the biggest proponent of longtermism, summarises the argument for it as:
1. Future people count.
2. There could be a lot of them.
3. We can make their lives go better.On the face of it, this is a convincing argument.
However, this post outlines my objections to it, summarised as:
1. Future people count, but less than present people.
2. There might not be that many future people.
3. We might not be able to help future people much.To this, I will add a fourth: there are trade-offs from this work.
Thank you for the feedback on both the arguments and writing (something I am aiming to improve through this writing). Sorry for being slow to respond, it's been a busy few of weeks!
I don't think there's actually any disagreement here except here:
I disagree, at least taking the MacAskill definition of as "the view that we should be doing much more to protect future generations". This is not just a moral conclusion but also a conclusion regarding how we should use marginal resources. If you do not think there is a causal way to affect future people, I think you must reject that conclusion.
However, I think sometimes longtermism is used to mean "we should value future people roughly similarly to how we value current people". Under this definition, I agree with you.