You can always keep deferring reasons. Spending any degree of time with a small child will prove that. He'll ask why something is, and you tell him, and then he'll say "Why?", and then you answer that, and he'll say "Why?", etc., etc. Even if the answer to the first "Why?" is precisely the same for two different observations, or even the first three "Why?"s, eventually the answers will start to diverge.
I give up. A dog that wants to chase its tail is gonna chase its tail.