Longtermism critique goes viral: from mosquito nets to 500-million-year math gone absurd

banteg · x · 2026-09-18

banteg shared and quoted visakanv's critique of longtermism within effective altruism.
The quoted greentext traces a familiar arc: start with spreadsheet-optimized giving (malaria nets), then follow the logic—future people count too → grandchildren → 500 years → 5000 → 500 million years—until a calculator shows any present-day donation's expected lives saved are swamped by far-future population, rendering the reasoning absurd.
visakanv's "antidote": imagine any longtermist from history acting on the information they had, and prediction errors quickly prove inevitable and ruinous.
A companion post argues for a humbler time horizon: 0.1% of thinking beyond 5 lifetimes, 40% on one lifetime, 60% on the next 50 years.

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