---
title: "I.J. Good"
type: "entity"
entity_kind: "person"
status: "hub"
canonical_name: "I.J. Good"
aliases: ["Irving John Good","Jack Good"]
first_seen: "2026-07-12T00:00:00.000Z"
writer_model: "claude-sonnet-5"
connects_to: ["intelligence explosion","ultraintelligent machine","existential risk","logarithmic scoring rule","Andrew Yao"]
---


I.J. Good (1916–2009) was a British mathematician and statistician — a Bletchley
Park cryptanalyst under Turing, later a statistician at Virginia Tech — whose
1965 essay coined "intelligence explosion" and the "ultraintelligent machine,"
and whose 1998 reflection reversed his own earlier optimism into a warning that
such a machine could bring human extinction. His 1952 logarithmic scoring rule,
developed decades earlier in an unrelated context (calibrated probability
elicitation), turns out to be mathematically identical to the cross-entropy loss
now used to train large language models — a genuine cross-domain bridge, not
mere trivia. He matters to the vault as the earliest anchor for the
intelligence-explosion-to-extinction lineage that later AI-safety rhetoric,
including [[claim-yao-frames-ai-as-extinction-level-new-species|Andrew Yao's
2024 "new species" warning]], echoes decades later from an unrelated field.

## References
- [[claim-ij-good-1965-ultraintelligent-machine-coined-intelligence-explosion]] — the 1965 coinage
- [[claim-ij-good-1998-reversed-intelligence-explosion-to-extinction]] — the 1998 reversal to existential risk
- [[claim-ij-good-1952-logarithmic-score-is-the-llm-cross-entropy-loss]] — the 1952 scoring-rule/cross-entropy bridge
- Related: [[claim-yao-frames-ai-as-extinction-level-new-species]] — a later, unrelated-field echo of Good's extinction framing
- Captures: 2026-07-12 (original three notes); 2026-07-27-does-the-carnegie-endowment-piece-confirm-cnaisdas-bilingual (flagged Good as an entity candidate — hub built this session)