What happens when UFO eyewitness testimony contradicts expert scientific testimony? What do you do? Well, if you’re a reasonable person, it would seem that wherever eyewitness testimony and expert scientific testimony are at odds, you’ve got to considerably lower your confidence in eyewitness testimony. This is true even if it appears superficially quite compelling.
Put more directly: UFO belief has the exact same problem as Bigfoot belief. Like alien belief, Bigfoot belief relies primarily upon decontextualized eyewitness testimony and ambiguous or hard to interpret photographic evidence. The reason that mainstream biologists don’t go chasing after Bigfoot on hearing eyewitness testimony of sightings is because Bigfoot cannot be incorporated into any plausible primate evolutionary scenario that would land such a creature in North America ahead of humans. Hairy upright walking primates evolved in Africa, and there were no upright walking primates of any sort in North America until humans got here about 20,000 years ago. Period. The geography associated with primate evolution is simply too well established to overturn on the basis of scattered North American Bigfoot sightings.
Likewise, UFOs, to be among us, would have to overturn everything we think we know about the plausibility of moving large organisms around the universe. The distance between stars is simply too vast to accommodate biological alien travel in metal spaceships to neighboring solar systems. And even if you posit wormholes as methods of alien transportation, there is simply no way, at present, to rationally evaluate such a speculation’s probability.
Thus, short of a UFO landing unambiguously before CNN cameras on the White House lawn, and staying put for scientific investigation, or a Bigfoot stepping out of the woods and being hit by a passing car on a mountain road, UFOs and Bigfoots are simply unable to startle existing and well established scientific paradigms sufficiently to drive the creation of new paradigms.
Sorry. You need big power to blow up a longstanding scientific paradigm. Only extraordinary lines of evidence will do. Astrophysics and primate evolutionary biology are simply too well established to permit UFO belief or Bigfoot belief more than a vanishingly small probability of being true. Epistemically, UFO belief and Bigfoot belief are struggling with equivalent difficulties of justification.