Donald H. Menzel — 1968 House UFO Symposium statement (verbatim quotes)
- Source: Menzel’s prepared statement for the 1968 House Symposium on UFOs (files.ncas.org/ufosymposium/menzel.html). He submitted a paper for the record but did not testify in person. Captured 2026-05-29.
- Primary for menzel-harvard-debunker.
Thesis: “some 90 per cent of the solved cases result from the presence of material objects in the atmosphere.” He asserted that “natural explanations exist for the unexplained sightings” — i.e., explanations exist even for the cases not yet explained.
His catalog of prosaic causes:
- Optical phenomena: “Layers of ice crystals … can perform evasive action” (sun dogs / mirages)
- Aircraft: “Reflections from airplanes, banking in the sun, simulate saucers”
- Balloons/objects: “weather balloons lighted or unlighted … Advertising planes or illuminated blimps”
- Temperature inversions bending light to create illusions
- Physiological: after-images, eye-movement artifacts
On the extraterrestrial hypothesis (his inversion of the Holmes maxim): “we have not excluded all the impossibles” before accepting the alien-spacecraft theory — so ET is never the warranted conclusion.
On UFO believers: “The believers are too eager to reach a decision … Having no real logic on their side, they resort to innuendo as a weapon”; “many honest observers can make honest mistakes.”
Note the symmetry McDonald flagged: Menzel charges believers with being “too eager to reach a decision,” while himself asserting that “natural explanations exist for the unexplained sightings” — reaching the prosaic decision before the explanation exists. McDonald (an actual atmospheric physicist) checked “case after case” and found Menzel’s meteorological-optics explanations “very far removed from the well-known principles and quantitative aspects of meteorological optics.”