Discussion on question by user1450877: Why don't children know why they do things?

When I was growing up my mom would ask me why I did so-and-so. I thought the question was "what thought process led you to do that?" and I looked inside myself, identified the chain of thoughts that led me there, and answered truthfully. Then, however angry my mom was with me, she would become even angrier. Turns out she was really asking "how do you justify what you did" or "why did you think that was the right thing to do?" She thought I was "making excuses". I quickly learned to never answer that question again.

A few years ago, I tried to light my cigarette. It was still behind my ear. I instinctively tried to light it behind my ear and burned off a big patch of hair. I still don't know why I did it. You could argue that "because I wanted to light the cigarette" is the answer; but then again, it's not the answer to the question "why did I do it that way instead of putting the cigarette in my mouth?". The question "why did you do that?" can be interpreted in several ways, and children may be responding to a different interpretation than you were expecting.

Others are providing solid answers, but just kudos from me for not phrasing this as a “lie.” Children don’t lie like this. They are simply sorting out their impulses versus what they know they should do. Even as adults we struggle with this. In the case of your child, it’s pretty clear to me they just don’t know how to articulate their thoughts into words. Or even understand on a basic level, “I just wanted to.”