Explanations and opinions

An Air Force study by Battelle Memorial Institute scientists from 1952-1955 of 3200 USAF cases found 22% were unknowns, and with the best cases, 33% remained unsolved. Similarly about 30% of the UFO cases studied by the 1969 USAF Condon Committee were deemed unsolved when reviewed by the American Institute of Aeronautics and Astronautics (AIAA). The official French government UFO scientific study (GEIPAN) from 1976 to 2004 listed about 13% of 5800 cases as very detailed yet still inexplicable (with 46% deemed to have definite or probable explanations and 41% having inadequate information).[51]

Despite the remaining unexplained cases in the cited scientific studies above, many skeptics still argue that the general opinion of the mainstream scientific community is that all UFO sightings could ultimately be explained by prosaic explanations such as misidentification of natural and man-made phenomena (either known or still unknown), hoaxes, and psychological phenomena such as optical illusions or dreaming/sleep paralysis (often given as an explanation for purported alien abductions).

Other skeptical arguments against UFOs include:

* Most evidence is ultimately derived from notoriously unreliable eyewitness accounts and very little in the way of solid or other physical evidence has been reported.
* Most UFO sightings are transitory events and there is usually no opportunity for the repeat testing called for by the scientific method.
* Occam's razor of hypothesis testing, since it is considered less incredible for the explanations to be the result of known scientifically verified phenomena rather than resulting from novel mechanisms (e.g. the extraterrestrial hypothesis).
* The market being biased in favour of books, TV specials, etc. which support paranormal interpretations, leaving the public poorly informed regarding more mundane explanations for UFOs as a possibly socio-cultural phenomenon only.[52]