Robert R. Provine has made a career (and a recent book) of researching our bodily functions. Nicholas Day spoke to him about the philosophical importance of tickling:
What’s at work in tickling, he argues, is the neurological basis for the separation of self from other. After all, as Provine noted so indelicately, you can’t tickle yourself. Your body knows that you are you; you can’t fool it. “Otherwise you’d go through life in a giant chain reaction of goosiness,” Provine says. “You’d be afraid of your own clothing if you could never distinguish between touching and being touched.” When a baby senses a foreign hand lightly brushing his bare feet, he’s experiencing something that is recognizably other—which means that there’s something that isn’t other, too: There’s himself. Tickling is central to who we are, because it is part of how we establish that there’s a we there.
The Dish 