Little A (thoughtfully, while looking up from playing Minecraft on the iPad): “I wish I had powers over time…”
Me: “What for?” (thinking it was going to be something like making school time go faster and play time go slower)
Little A: “So that I could travel forward in time to when I’m a grown-up, and have already taken over the world, and then I could kill my future self and take her place, so that I could rule the world while still being a kid, without having to wait to grow up!”
Me (somewhat at a loss for words): . . .
Little A: “Pretty clever, huh?”
Me: “Er… Well, it’s certainly an original idea. But there is one flaw with it, which you might be able to see if you think about it a bit…”
Little A (thinks for a minute): “No, what?”
Me: “If you go forward in time and kill your future self and take her place, then when you’ve grown up, your child self will come forward in time and kill you. So your days of ruling the world will be numbered…”
Little A: “That’s OK – because if I had powers over time, I would also be able to travel back in time and start the whole process over again, as many times as I wanted, so then I could rule the world as a kid forever! I’d do it as soon as I became a teenager, every time, so then I would never become an adult at all, and I’d never get killed!”
I am pretty sure there was still some kind of logical flaw there, but by that point my brain had pretty much exploded anyway.