Why compute-extrapolation arguments for AGI timelines are flawed, and why Kurzweil's 1999 bet was luck

phl43 · x · 2026-09-06

phl43 lays out a systematic critique of a common AGI prediction genre: estimate the compute needed to emulate a human brain, extrapolate compute growth, and conclude AGI arrives shortly after crossing that threshold.

Even granting the safest assumption—that compute keeps growing at a constant or accelerating rate—he argues the reasoning collapses because our understanding of the brain is far too poor: the models used to estimate emulation requirements are almost certainly wrong, possibly by a lot, likely missing key biological mechanisms.

Context: the debate started when @akarvonen defended Kurzweil's 1999 prediction built on extrapolating compute growth against human-brain FLOPS ('in retrospect, that's all you need to predict AGI'). phl43 calls it a terrible argument and plans a full post; @stanislavfort adds that we don't even know how the brain implements its learning algorithm.

Related event: Debate Erupts Over Whether Compute Extrapolation Can Predict AGI(6 posts)→

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