Little Johny Bayesian

Followup to: Rationalist Storybooks: A Challenge

This was originally a comment in response to a challenge to create a nursery rhyme conveying rationality concepts, but, at the suggestion of Eliezer, I’ve made it into its own post.

Little Johny thought he was very bright,
But the schoolkids did not—they would laugh when he came in sight.
He could count, sing, and guess the weather.
Then one day, Big Bill said “Real bright boys will grow a feather.”

“Ach!” he cried, “Could it be true?”
“Then I’m not bright, which makes me blue.”
So he went home, and searched all over.
And then found growth on his head, clear as a clover.

“It is true, feathers are sprouting!”
“It’s proof that I’m bright!” So he stopped pouting.
He ran to show his mom, nearly tripping over some eggs,
When he saw on TV “Bright boys will grow long legs.”

So he waited for weeks and weeks for to find proof,
Worried over his brightness, and staying quite aloof,
Until one day, feeling in a pinch,
He grabbed a tape measure, and found his legs had grown a whole inch!

So he leaped off to school, but a scientist walked by,
And Johny overheard him say, that real bright boys could fly.
“The hair, the legs, from these I know
Of my brightness. The flying thus follows, so...”

Little Johny plotted of his grand display,
Standing high on a wall, he would proudly say
“Behold, I have proof that I’m bright!”
And he would deftly leap off, and soar into flight.

So he climbed up the wall, and made his speech,
But there his plan stopped with a screech,
For he hit the ground hard with a smack,
Leaving his leg all bloody and black.

As the other children laughed, he tried to explain,
Of the things that he heard, and why he had taken it to his brain,
“They came from on high, from people who knew
I looked at myself, and saw they were true.”

They laughed, “You’re too eager to believe, you fool.
Your feathers are just hair, all boys grow long legs as a rule.
Yes, if all you heard were true, you’d fly, but you’ll find out,
That if you do logic with garbage, then you’ll get garbage out.”

So Johny thought wrongly, and got his leg in a cast,
He had sought fame in the schoolyard, but now that’s all past.
He’s taken the lesson to heart, no longer believes all he hears.
So he doesn’t believe them when they say he’s not bright—brightness doesn’t come from peers.