Plenty
How common is it to start with? rare things make most alarms false
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Plenty counted things. All the things. It was her favourite hobby.
She was a meerkat-tween with sandy fur, dark rings round her eyes, a yellow sun hat and a little clicker counter on a cord round her neck. Every morning she stood up tall on the BiasForge beach and counted: gulls, shells, footprints, bottle caps. Click, click, click.
One morning a young hare came running down the sand, waving a metal detector over her head. "It beeped!" she shouted. "It beeped! It's ninety-nine percent accurate, the box says so! There's treasure under here, I'm sure of it!"
Plenty clicked her counter once, thoughtfully. "Before you dig," she said, "can I ask a question? How much treasure is on this beach, to start with?"
The hare stopped. "I... don't know. Not much, probably. Treasure is rare."
"Very rare," Plenty agreed. "I've counted. About one real coin for every thousand bottle caps." She waved at the sand, glinting with old caps. "So even a good detector, beeping wrong just once in a hundred times, will beep at loads of bottle caps for every real coin. Most of your beeps are going to be caps."
Plenty had not always asked that question.
When she was small, she believed every exciting sign. She saw a shimmering shape in the sea and was sure it was a rare golden fish. It was a crisp packet. She heard a rustle in the dunes and was sure it was the very rare striped fox her book talked about. It was a gull. Each time she got so excited, and each time she felt foolish afterwards, though she couldn't work out why her guesses kept going wrong.
Solon, the mentor at the lab, found her sitting on a dune, glum. "Your guesses keep jumping to the rare thing," Solon said gently, "because the rare thing is exciting. But there are far more gulls than striped foxes, and far more crisp packets than golden fish. When something is rare to start with, a clue that seems to point at it is still usually pointing at something ordinary."
"So how do I stop jumping?" Plenty asked.
"Count first," said Solon. "Before you trust a clue, ask how common the thing is to start with. Scientists call that the base rate. People forget it all the time, especially when the clue is vivid."
So Plenty started counting. How many gulls, how many foxes. How many crisp packets, how many golden fish. How many bottle caps, how many coins. Once she had the counts, the exciting clues stopped knocking her over. She still loved a surprise. She just didn't believe every surprise straight away.
She came to work at BiasForge because it was a place for learning exactly this.
"What will you show visitors?" Solon asked.
"How to count before you jump," Plenty said, and clicked her counter.
Whim, the quick, gut-feeling part of everyone's thinking, bounced on the sand. "But the beep is SO exciting."
"It is," said Plenty. "That's why it's so easy to forget the bottle caps."
The hare came back later with a card from the lab. "A town has 1,000 dogs," she read, "and only 10 of them are the rare spotted kind. A camera that spots spotted dogs gets it right most of the time, but it also mistakes about 50 ordinary dogs for spotted ones each year. The camera flags a dog. Is it probably spotted?"
She started to say "yes," then stopped, and looked at Plenty's counter.
"Count first," Plenty said.
The hare counted on her paws. "At most ten real spotted dogs. And about fifty ordinary dogs flagged by mistake." Her eyes widened. "So most flagged dogs are ordinary ones! Probably not spotted."
Muse, the careful, slow-down part of everyone's thinking, smiled from the boardwalk. That was the move.
As the sun went down, the hare sat beside Plenty on the dune.
"Doesn't counting make everything less exciting?" she asked.
Plenty thought about the crisp packet in the sea and the gull in the dunes.
"I worried it would," she said. "But it's the other way round. When I used to jump at every clue, I was always being let down. Now, when I count first, I'm not let down any more." She clicked her counter, slow and contented. "There's a steady, unhurried feeling in it. Like standing up tall on a dune and seeing the whole beach at once. And when a real coin does turn up, after all those bottle caps, it feels even better, because I know just how rare it is."
The hare clicked an imaginary counter of her own, and Plenty watched the jittery excitement settle into something calmer and brighter.
The BiasForge ensemble
Plenty is one of the friends in BiasForge. Each friend shows you one idea by how they act; meet them all and you have the whole subject.
