Ways in which conversations with my two-year-old, in which his contribution is the question "why?", end

1. Infinite causal regress, historical
Why can't we go into the playground?
Because it's locked
Why?
Because the man didn't unlock it
Why?
Because he couldn't come here this morning
Why?
Because his car broke down
Why?
Because he left the lights on
Why?
Because -- hey! look at this stick!

2. Finite causal regress, teleological
Where are we going?
We're going to the post box
Why?
Because I want to post a letter
Why?
Because I want to send some photos to grandpa and grandma
Why?
Because I think they'll be happy
Why?
Because I do

3. Meta-explanatory regress, terminated by an inability to generalise further
Say sorry to the boy
Why?
Because you shouldn't hit people
Why?
Because it's wrong
Why?
Because it's wrong to hurt people
Why?
Because I say so