The Nature of Science 15network of satellites and radar; we can detect virtually anything moving in the skies any-
where in the world now—yet we have never received a reliable indication of a UFO, only
these unverifiable claims made by random plane or ground observers and photos that have
been documented as fakes. Nearly everyone carries a cell phone camera with them at all
times nowadays, yet there are no better photos than before—in fact, the quality of the evi-
dence is getting worse now that everyone has a camera. Certainly, it is possible that aliens
have visited us, but such an extraordinary claim requires higher levels of proof than ordi-
nary science, and the evidence provided so far is pretty flimsy.
Likewise, the claim that odd “monsters” live in remote places and have escaped sci-
entific attention (cryptozoology) is an extraordinary claim that requires more than the usual
level of documentation required to describe a new species of insect. Take, for example, the
Loch Ness monster. We give great credence to a few blurry photos (most of which have
now turned out to be frauds) or to eyewitness accounts (which only show how easily the
human mind is deceived), but every thorough study of Loch Ness has failed to produce
anything conclusive. No one seems willing to answer the harder questions: If there is a
plesiosaur or similar beast living in Loch Ness, how does it survive alone? Large beasts like
the “monster” that have supposedly lived for centuries would require a whole population
of such beasts, yet there is no conclusive evidence that even one exists. The believers also
ignore another inconvenient geologic fact: Loch Ness is a glacial valley that was filled with
ice 20,000 years ago and only now has water in it during our current interglacial period.
So where did the monster live before it became trapped in Loch Ness? And if there were
enough of them to form a population, why have they never been found in any other body
of water anywhere in the world?
Similar flaws apply to the claims of the Bigfoot or Sasquatch in the Pacific Northwest, or
the Abominable Snowman or Yeti in the Himalayas, or the supposed living sauropod dino-
saur Mokele-Mbembe in the Congo jungle. All the “evidence” for these beasts is inconclusive
or admitted to be fraudulent, and there would have to be a big population of them (never
detected) for us to still witness them. We don’t know for sure that such beasts don’t exist, but
they are so remarkable that they require much better proof of their existence (especially in
this overpopulated world where the truly unexplored, dark regions are nearly gone) than
has been presented so far.
- Burden of Proof
Related to the first principle is the idea of burden of proof. In a court of law, one side (usually
the prosecution or plaintiff) is assigned the task of proving its case “beyond a reasonable
doubt,” (in a criminal case) or “based on the preponderance of the evidence” (in a civil case),
and the defense often needs to do nothing if the other side has not met this burden of proof.
Similarly, for extraordinary claims that appear to overthrow a large body of knowledge, the
burden of proof is also correspondingly greater. In 1859 the idea of evolution was controver-
sial, and the burden of proof was to show that evolution had occurred. By now, the evidence
for evolution is overwhelming, so the burden of proof on the anti-evolutionists is much
larger: they must show creationism is right by overwhelming evidence, not just simply point
out a few inconsistencies or problems with evolutionary theory. Likewise, the evidence that
the Holocaust occurred is overwhelming (with many eyewitnesses and victims still alive and
many Nazi documents that describe what they did), so the Holocaust denier has to provide
overwhelming evidence to prove that it did not occur.