I think someone can have absolutely no idea why they did something, with those words.
You don't always get to do what you want. The interupt point between wanting something and yet not just instantly doing it is part of what identifies an adult. More specifically a self enacted interupt point. Self control.
And then maybe you get someone who is ostensibly an adult - but the instant they wanted to do something, they just did it. You can try and tell them they don't know why they were compelled to do it, but they will act like 'because I wanted to' is some kind of answer. There is nothing in between desire and enactment of desire. With nothing in between, there is only ignorance.
If your choosing what food you want to eat or what music your going to buy, it's cool enough to let go and just let desire go straight through to enactment (well, within certain limits with food, for health, and certain limits with music, for financial health). It's not like you have to do it for all things. But then again these exampless are mere frivolities.
Without any interupt between desire and enactment, without being able to describe any process of thought in terms of whether to let a desire 'through', I don't think anyone knows what they are doing, except at the most childish 'I wanna' level.
Side note: Just to give context if you haven't looked at my profile, this is a secondary blog for me. Like a sub folder. Yep, some people have more than one blog - golly! The other one is over here. Much video game and RPG talk there!