EVENT
The Sagan-Mayr Exchange
The 1995–1996 public debate between Carl Sagan and Ernst Mayr over the probability of intelligent life elsewhere in the cosmos — the astrophysicist counting planets, the biologist counting contingencies.
In 1995, a public exchange unfolded between Carl Sagan and Ernst Mayr over the probability of finding intelligent life elsewhere in the cosmos. Sagan, arguing from the perspective of an astrophysicist, pointed to the billions of stars, the billions of planets, and the statistical likelihood that conditions favorable to life exist elsewhere. Mayr, arguing from the perspective of a biologist who had spent seven decades studying the specificity of evolutionary outcomes, replied that the astrophysicist's statistics were irrelevant to the biological question. The existence of favorable conditions does not entail the emergence of intelligence, because the emergence of intelligence requires not just favorable conditions but a specific historical sequence — a sequence that, on the only planet where it has been observed, involved a chain of contingencies so particular that its repetition elsewhere is unknown in probability.
In The You On AI Field Guide
The exchange was published in Bioastronomy News and subsequently reprinted in collections. Its substantive content is Mayr's argument that historical contingency in evolution
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