Robert A. Freitas, Jr.
Xenology Research Institute. 8256 Scottsdale Drive Sacramento, California 95828
Icarus 62:518-520 (1985)
Received June 25, 1984: revised March 18, 1985
The "Fermi Paradox," an argument that extraterrestrial intelligence cannot exist because it has not yet been observed, is a logical fallacy. This "paradox" is a formally invalid inference. both because it requires modal operators lying outside the first-order propositional calculus and because it is unsupported by the observational record. © 1985 Academic Press. Inc.Entire article.
Renewed activity in the field of Search for Extraterrestrial Intelligence (SETI) has stimulated interest in an old argument purporting to show that ETI cannot exist. Known as the "Where Are They?" question or the "Fermi Paradox," this sophism posits that in time an intelligent extraterrestrial species must achieve high technology, exploring and colonizing first its planetary system, and later the Galaxy, as humanity has explored and colonized the Earth. These beings should have been able to travel to Earth, but we see no evidence of such visitations, hence ETI cannot exist. Proponents of the "paradox" (e.g., Hart, 1975; Tipler, 1980; Hart and Zuckerman, 1982) admit that it is incomplete in the loose form outlined above. but argue that alternatives purporting to explain the paradox (e.g., Ball, 1973; Sagan and Newman, 1983) are invalid or lead to contradiction or impossibility. This position has been weakly challenged (Cox, 1976; Schwartzman, 1977; Papagiannis, 1980; Stephenson, 1982), but the debate continues.
Tags: Fermi Paradox, Life on Other Planets, Astrobiology.