On tickling

Tickling has always baffled philosophy.

Poised right at the boundary between delight and discomfort, tickling is the kind of blend that messes up our best theories.

As a purely intellectual exercise, we could easily imagine Plato’s Philebus taking place in a cave where Socrates, dressed in latex and gripping a riding crop, interrogates his companions about the nature of pleasure — only to conclude, firmly, that tickling is a mixture of enjoyment and pain that leans closer to the latter. How we calibrate that mixture generally determines how we feel about tickling.

Man is a rational animal, but first he is a ticklish one. Aristotle, in De Partibus Animalium (“Parts of Animals”), attributes this peculiar sensitivity to our delicate skin and to our being the only creatures that laugh. He even placed the question of why we can’t tickle ourselves in his Problemata, hurrying to conclude that it’s because the element of surprise is missing.

Tickling, notably, escapes our ability to describe it. “It consists in a certain agreeable shock that usually causes involuntary laughter,” and the occasional trickle of pee in some cases.

Both Francis Bacon, to whom we owe the scientific method, and Charles Darwin, to whom we owe its most beautiful application, agreed that tickling could be tied to a particular mental state, but they disagreed on whether that state was necessary.

For Darwin, the nature of tickling was primarily social, so much so that if a stranger tickled a child, the child would scream in horror. For Bacon, that was beside the point: even the most bitter man cannot help but laugh if you tickle him. I can vouch for that.

Tickling also presents a peculiar metaphysics. If we ask where the tickle actually resides, Galileo would say — in Il Saggiatore (1623) — that the quality of “ticklishness” belongs not to the object that provokes it but to the person who feels it. This distinction between primary and secondary qualities, which seems basic to us now, caused enough of a stir to lay the groundwork for the scientific study of the senses that Descartes would pick up a few decades later.

Our relationship to tickling can probably be inferred from our age. As neuroscientist Robert Provine explores in *Curious Behavior* (2012), tickling appears to be one of the most primitive forms of socialization among little critters (human and otherwise).

Tickling hasn’t only been observed in other primates, but also in elephants, rats, and even trout, as Maria mentions in Shakespeare’s Twelfth Night (1601). Sorry, Aristotle.

For Provine, this preverbal form of communication is what introduces us to the distinction between our own bodies and the surrounding world. Tickling, he argues, creates intimacy through a kind of playful, harmless aggression. It’s even our inability to tickle ourselves that teaches us about the limits of our sensory experience and the idea that beyond the “me” there is an “other,” and then an “us.”

The bafflement tickling produces comes from the fact that our defensive response is the exact opposite of what we’d expect from an attack. It’s the uncontrollable laughter that makes someone keep going, even though its nature is torturous rather than jokey.

That still doesn’t explain, however, why tickling was selected for in evolution. One hypothesis, proposed by J. C. Gregory in 1924, is that our sensitivity to tickling is greatest in the areas of the body most vulnerable in hand-to-hand combat, and tickling teaches us to protect them.

The people who usually tickle us, of course, tend to be the people who take care of us. That’s why FBI agent Holden Ford in Mindhunter (2017) is so right to be suspicious of the school principal who teaches his students a lesson by tickling them. Paradoxically, if the story had been that he hit them with a ruler, nobody would have batted an eye.

This theory stumbles when it tries to explain why the hands and fingers, especially vulnerable in a fight, are among the places where we’re least ticklish — or what the benefit of laughing in combat would be, beyond the possibility of convincing your attacker that you have, in fact, lost your mind and that they now run the risk of losing an eye.

Christine R. Harris, ticklologist, proposes that this is precisely the function: we smile and laugh so that the tickling continues, and we become more and more capable of surviving. When a real fight finally comes, no one will be able to stop us. Hence the old adage: “The quill is mightier than the sword.”

Tickling confuses and frightens us because it shows how easily we can lose control. We want it to stop, we want to scream and cry — yet our bodies keep howling with laughter. The discomfort and pain become unbearably private when our own physicality betrays us. There’s no greater prison than losing control over your own body. There’s a reason tickle torture exists.

Come to think of it, the laughter tickling provokes isn’t like any other. What looks like a smile is actually a threat display: we’re really baring our teeth. And past a certain point, laughter is no longer the social phenomenon that goes with amusement; it’s a spasmodic reflex to release tension that can even lead to cataplexy, or loss of muscle control.

For tickling to stay a game, it has to be brief, gentle, and consensual, with close attention paid to the other person. And not all tickling is the same. In 1897, psychologists G. Stanley Hall and Arthur Allin divided tickling into two categories: high-pressure, fingers-in-the-ribs laughter-inducing tickling, called gargalesis; and a light, feathery motion across the skin, called knismesis.

The challenge of tickling lies in figuring out where the other person’s pleasure ends. After all, kids — and adults — crave laughter, connection, and physical play, and tickling is a shortcut to all of that. It’s worth asking whether there are other ways to achieve the same thing without reducing the other person to a bundle of helplessness.

It’s also worth mentioning that if that is what we like, there’s nothing to be ashamed of. “Knismolagnia,” from the ancient Greek κνησμός (knēsmós, “itching”) and λαγνεία (lagneía, “intercourse”), is the sophisticated word for the sexual fetish of arousal caused by tickling — and it completes our mental image of Socrates asking who’s up for more pleasure, or more pain. Rawr.

As for why we can’t tickle ourselves on our own, there’s no definitive answer. One, offered in *Big Questions from Little People (answered by Some Very Big People)* (2012) by neurologist David Eagleman, has a lot to do with how our brains work. Thanks to past experience, the brain knows (almost) exactly what will happen. And if something changes, it adjusts and makes new predictions. This includes anticipating how our body is going to feel, and that’s what takes all the fun out of tickling.

One roundabout, sneaky way of tickling ourselves, however, seems to be forgetting money in a pocket, which brings back both our capacity for surprise and the subtle pleasure of the unexpected — along with the painful awareness that inflation is as real as a chair to the face.

Although the history of science — and philosophy — usually tidies up the story around matters perhaps more dignified, it’s still extraordinary how a phenomenon like tickling has all the ingredients to light up the most restless minds of every era.

After all, tickling confronts us with a handful of paradoxes that could only be ignored out of reckless negligence. If everything comes down to sensitivity, it’s hard to explain why we’re more ticklish on the soles of our feet than on our hands, where our sense of touch is keener. Or why, if tickling causes us pain and helplessness, our reaction is the exact opposite of what we might expect. Tickling even flips the most pedestrian notion of cause and effect: the lighter the touch, the more powerful its effect.

Probably the greatest philosopher of tickling was Descartes, who never stopped insisting that the senses tend to deceive us. In his critique of the tradition before him, he set out to rethink their role, especially that of touch, which allowed him to reconsider human nature and our place in the material world — with consequences that were not only ontological and epistemological but also social, political, theological, and even artistic.

Despite his reputation for being uninterested in the bodily, his interest in tickling can’t be overstated. Descartes, like so many others, also paused over the peculiar existence of tickling on the threshold between pleasure and pain, something that, paraphrasing his fan David Hume, could be described as “a pleasant sensation that, taken to excess, becomes painful.”

Descartes’s ultimate aim was nothing less than to point out that, despite the richness of sensory experiences like those provided by touch, we must ultimately think beyond the limits of the senses in order to embrace the true nature of things.

Or, as must have appeared in some early, lost note in a forgotten corner of history: I am tickled, therefore I am.

Etching by Francesco Londonio da Napoli (1763) of shepherd tickling neck of sleeping shepherdess with piece of straw.

This text was originally sent on May 2nd, 2021 through Cómo funcionan las cosas, in Spanish.

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