Kyle Hill has a great cryptozoology post up on his But Not Simpler Scientific American blog today, titled “Why Bigfoot is Unlikely Only If You Know What ‘Unlikely’ Means.” The piece includes a shout-out for my new book with Don Prothero, Abominable Science!, and also includes some quotes drawn from an email exchange with yours truly. I thought I might share some more of those comments here for your interest:
Hill: The theme of the piece is “The Unlikely” and I want to look at how the un-likelihood of something is treated differently in science and pseudoscience.
Loxton: In some ways pseudoscientists and paranormal enthusiasts such as cryptozoologists assess probability very differently from scientists. A scientist generally starts with the conservative working assumption that proposed new ideas are not true or that hypothetical new entities do not exist, and then revises her probability estimate upwards only when the evidence forces her to do so. A pseudoscientist typically starts with the assumption that a novel proposal seems to be true, and then revises her probability downward as the evidence leaves her no choice—if she is willing to surrender the possibility to any degree at all. (Some paranormalists are very reluctant to do so. Despite all the exposed hoaxes and bad ideas in cryptozoology, for example, I’m not sure that any cryptid or class of evidence has ever been abandoned or ruled out by the community of cryptozoologists overall.)
Assuming we’re all willing to follow the evidence, the more conservative approach to assessing likelihood is not necessarily the only game in town. It depends if you are more worried about accepting falsehoods (a “Type I error”) or rejecting truths (a “Type II error”) . Psychologist Ray Hyman made this point in regard to a parapsychology enthusiast with whom he had engaged in dialogue:
Dave sees Type II errors as much more serious than Type I errors. For me, the skeptic, it is just the opposite. And this is not a matter of rational judgment as such. But it is more of a matter of how we weigh the costs of each type of mistake. Dave, like all believers in the paranormal, believes that the phenomena of reincarnation, psychic communication, mystical experiences, and the like are just too important and meaningful to overlook because of excessive demands of scientific rigor.1
Cryptozoologists do much the same.
Another systematic difference between how skeptical scientists and paranormal proponents assess likelihoods is in the weight that each gives to eyewitness testimony regarding alleged personal experiences with the paranormal. Proponents tend to see every eyewitness account as increasing the probability at least a little,2 while skeptics emphasize a proverbial warning: “the plural of ‘anecdote’ is not ‘data.’” A mountain of anecdotes is by itself just so much uncorroborated noise. Worse, new anecdotes can actually decrease the likelihood that a disputed phenomenon actually does exist. If eyewitness accounts implicitly entail predictions for evidence that consistently fails to emerge (if hunters see sasquatches, for example, then hunters can also shoot them—but they don’t) then new accounts diminish the chances rather than increasing them. This point was wisely argued by Bigfoot proponent Grover Krantz:
Many sasquatch enthusiasts seem to think that by finding more widespread [anecdotal and trace] evidence of the species, they are in effect strengthening the argument that the species is real. Up to a certain point this reasoning is valid … But when it is suggested that a wild primate is found native to all continents, including Australia, then credibility drops sharply. … Beyond a certain point, it can be argued that the more widespread a cryptozoological species is reported to be, the less likely it is that the creature exists at all.3
Krantz was one of the rare trained scientists to promote Bigfoot, so it is not surprising that he saw this point so clearly. Most cryptozoologists cheerfully ignore his warning. For most, the mountain of evidence only grows, forever. It never topples under its own weight.
In other ways, however, people all tend to assess probability the same, no matter what background we come from: when something seems overwhelmingly well attested, overwhelmingly consistent with previously admitted evidence, we stop thinking in probabilistic terms and start thinking of things as facts. To many Bigfoot enthusiasts, the existence of sasquatches seems like a given—a rock solid established fact, like the existence of France. To some, the accumulated mass of evidence seems just too large to explain away; to others, a visceral personal experience makes probabilistic arguments seem moot. “I know what I saw,” trumps abstract reasoning almost every time. And honestly, how could it not? That’s human. It’s the way we’re built.
- Ray Hyman. The Elusive Quarry: A Scientific Appraisal of Psychical Research. (New York: Prometheus Books, 1989.) p. 423
- Consider the advice from pioneering cryptozoologist Bernard Heuvelmans: “Needless to say, the more witnesses who can be produced for each particular sighting—and, in the long run, for each kind of hidden animal—the stronger the case. Essentially, this is because an abundance and unanimity of testimonies has perforce greater weight. … Accordingly, the inquiring cryptozoologist should endeavor, as his first important task in the field, to collect as many eyewitness testimonies as possible….” Bernard Heuvelmans. “The Sources and Method of Cryptozoological Research.” Cryptozoology: Interdisciplinary Journal of the International Society of Cryptozoology. Vol. 7, 1988. p. 5
- Grover Krantz. Bigfoot Sasquatch Evidence. (Surrey: Hancock House, 1999) p. 197
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