Illustration by Jon Klassen

Consider the yeti. Reputed to live in the mountainous regions of Tibet, Bhutan, and Nepal. Also known by the alias Abominable Snowman. Overgrown, in both senses: eight or ten or twelve feet tall; shaggy. Shy. Possibly a remnant of an otherwise extinct species. More possibly an elaborate hoax, or an inextinguishable hope. Closely related to the Australian Yowie, the Canadian Nuk-luk, the Missouri Momo, the Louisiana Swamp Ape, and Bigfoot. O.K., then: on a scale not of zero to ten but of, say, leprechaun to zombie, how likely do you think it is that the yeti exists?

One of the strangest things about the human mind is that it can reason about unreasonable things. It is possible, for example, to calculate the speed at which the sleigh would have to travel for Santa Claus to deliver all those gifts on Christmas Eve. It is possible to assess the ratio of a dragon’s wings to its body to determine if it could fly. And it is possible to decide that a yeti is more likely to exist than a leprechaun, even if you think that the likelihood of either of them existing is precisely zero.

In fact, it is not only possible; it is fun. Take the following list of supernatural beings:

__ Angels

__ Demons

__ Dragons

__ Pixies

__ Ghosts

__ Harpies

__ Elves

__ Mermaids

__ Loch Ness monster

__ Leviathan __ Giants

__ Pegasus

__ Centaurs

__ Unicorns

__ Tooth fairy

__ Phoenix

__ Werewolves

__ Vampires

__ Genies

__ Zombies {: legacyType="feature-small"}

Never mind, for now, whether or not you actually believe in any of these creatures. We are interested here not in whether they are real but in to what extent they seem as if they could be. Your job, accordingly, is to rank them in order of plausibility, from most likely (No. 1) to least likely (No. 20). Better still, if you are in the mood for a party game this Halloween season, try having a lot of people rank them collectively. I guarantee that this will produce a surprising amount of concord—who among us could rank the tooth fairy above the Leviathan?—as well as a huge amount of impassioned disagreement. The Loch Ness monster will turn out to have a Johnnie Cochran-level defense attorney. Good friends of yours will say withering things about mermaids.

What’s odd about this exercise is that everyone knows that “impossible” is an absolute condition. “Possible versus impossible” is not like “tall versus short.” Tall and short exist on a gradient, and when we adjudge the Empire State Building taller than LeBron James and LeBron James taller than Meryl Streep, we are reflecting facts about the world we live in. But possibility and impossibility are binary, and when we adjudge the yeti more probable than the leprechaun we aren’t reflecting facts about the world we live in; we aren’t reflecting the world we live in at all. So how, exactly, are we drawing these distinctions? And what does it say about our own wildly implausible, unmistakably real selves that we are able to do so?

In the fourth century B.C., several hundred years after the advent of harpies and some two millennia before the emergence of dementors, Aristotle sat down to do some thinking about supernatural occurrences in literature. On the whole, he was not a fan; in his Poetics, he mostly discouraged would-be fabulists from messing around with them. But he did allow that, if forced to choose, writers “should prefer a probable impossibility to an unconvincing possibility.” Better for Odysseus to return safely to Ithaca with the aid of ghosts, gods, sea nymphs, and a leather bag containing the wind than for his wife, Penelope, to get bored with waiting for him, grow interested in metalworking, and abandon domestic life for a career as a blacksmith.

As that suggests, for a possible thing to seem plausible it must be reasonably consistent with our prior experience. But what makes an impossible thing seem plausible? In a convoluted passage in the Poetics, Aristotle tells us that if an impossible thing would “necessarily” require something else to occur along with it, you should put that second thing in your story, too, because then your readers will be more likely to believe the first one. In other words, even something that is factually impossible can be logically possible, and how closely that logic is followed will affect how plausible a supernatural being seems.

There’s a reason Aristotle addressed this advice to writers and artists. Unlike most of us, they have practical motives for wondering how best to make imaginary things seem convincing, a problem that must be solved as much for “Vanity Fair” as for “A Wrinkle in Time.” Accordingly, creative types have done an unusual amount of thinking about plausible impossibility. In the seventeen-nineties, for instance, Samuel Taylor Coleridge set out to write a series of poems about “persons and characters supernatural.” To do so, he knew, he had to make the fantastical seem credible—“to procure for these shadows of imagination,” he wrote, in a soon to be famous phrase, a “willing suspension of disbelief.”

Coleridge was excellent at inducing a suspension of disbelief. That’s why we are as gripped by “The Rime of the Ancient Mariner” as the wedding guest within the poem who can’t tear himself away from the sailor’s tale—even though the tale itself is an outrageous one involving a magical albatross, a terrible curse, and a ship crewed by ghosts. Yet Coleridge was vague about explaining how exactly he did it. His only advice for making impossible things seem believable was to give them “a semblance of truth.”

“Now imagine how good that would look completely sweated through on the Twenty-third Street subway platform.” Facebook

Twitter

Email

Shopping

A little more than a hundred years later, a very different kind of artist got somewhat more specific. Although Walt Disney is best remembered today for his Magic Kingdom, his chief contribution to the art of animation was not his extraordinary imagination but his extraordinary realism. “We cannot do the fantastic things, based on the real, unless we first know the real,” he once wrote, by way of explaining why, in 1929, he began driving his animators to a studio in downtown Los Angeles for night classes in life drawing. In short order, the cartoons emerging from his workshop started exhibiting a quality that we have since come to take for granted but was revolutionary at the time: all those talking mice, singing lions, dancing puppets, and marching brooms began obeying the laws of physics.

It was Disney, for instance, who introduced to the cartoon universe one of the fundamental elements of the real one: gravity. Even those of his characters who could fly could fall, and, when they did, their knees, jowls, hair, and clothes responded as our human ones do when we thump to the ground. Other laws of nature applied, too. Witches on broomsticks got buffeted by the wind. Goofy, attached by his feet to the top of a roller-coaster track and by his neck to the cars, didn’t just get longer as the ride started plunging downhill; he also got skinnier, which is to say that his volume remained constant. To Disney, these concessions to reality were crucial to achieving what he called, in an echo of Aristotle, the “plausible impossible.” Any story based on “the fantastic, the unreal, the imaginative,” he understood, needed “a foundation of fact.”