The younger has recently learned from her cousin how to play the Pokémon card game and now she is teaching me.

She deals us each six cards.

“OK, you have to pick one of your cards that you think will beat my card and then you put that card down.”

“How can I tell which cards are better?” I ask.

“You just see which one is the best,” she explains.

“Yeah, but what makes one card better than another card? Is it to do with the numbers on the card? Or are certain characters better than others?”

She looks a little vague. “I’ll tell you when you put your card down if it’s better or not,” she says.

I narrow my eyes.

“Do you get it?” she asks.

“Not really,” I say, “but let’s just start playing and I’ll figure it out.”

We both put one card down.

“So whose card is better?” I ask. She examines them carefully. “Mine,” she says. “See how mine is shiny?”

“Oh, so all the shiny cards are better?” I ask.

“Yes,” she says, a little uncertainly.

“OK, let’s try again,” I say. I look at my cards. “None of my cards are shiny,” I say, “so I don’t know how to choose.”

“I can help you,” she says. I show her my cards. I point to one with a plucky looking panda on it. “What about him?”

“Yeah, he’s OK,” she says.

I put him down.

The younger puts her card down. “I win again!” she says.

Her card has some kind of exploding metallic abstract design on it.

“Why?” I say.

“Mine is a mega ex,” she explains.

“And what’s mine?” I ask.

“Yours is just ordinary,” she says. “It isn’t evolved.”

“OK,” I say, “but how am I supposed to tell that from looking at it?”

“Just look at my card!” she exclaims. “Look how much better it is than your card!”

I look at her card again. The design is, I guess, more complex than my card.

“Oh, fine,” I concede.

For the next round, I choose a card with a cute red bird on it. The younger lays down her card, which has some kind of green mollusc on it.

If the game’s logic is evolutionary, I feel pretty confident about this round.

“OK, I think I win this one,” I say.

“No you don’t!” she says, triumphantly. “Look how much better mine is than yours!”

“Yours is not better!” I protest. “Yours is just … just a snail, and mine is this nice bird!”

She looks at me severely. “Mine is a legendary from an ultimate universe.” she says. “And yours is just an ordinary creature that lives in … in the bushes.”

“OK,” I concede, because my bird is in the bushes in the picture. “But why does that make yours better?”

She sighs, exasperated. “Which sounds better to you,” she says, “‘a legendary from an ultimate universe’ or ‘an ordinary creature in the bushes’?”

“Well ‘a legendary from an ultimate universe’ sounds better,” I mutter, rolling my eyes and scowling.

“OK, so I won that round,” she announces. “Do you get how it works now?”