When you're digging and shoveling lime or sand or green manure into your garden, that's a legitimate question. You should know why and it should be specific.
But when you're plowing up the ground in order to be able to plant a garden? Well, that's a silly time to say Why? unless it's the dead of frozen winter and you're trying to plow permafrost. One does not ask, Why garden? -- it's too silly to deserve an answer.
When you're choosing a doctor or a midwife and a birthing place for the impending arrival, then Why? is the question to answer. Why that one? Why not this other one? Makes sense. Conscious choice of particulars in the midst of a given reality - this makes sense.
When you're happily married, asking Why do I want children? is slightly odd. Couples couple, and coupling makes babies. We have to choose to stop the forward momentum, if we want it stopped. It's called being normal and ordinary, and so normal and ordinary that anything else is an exception. Exceptions there may be, but, Why am I normal? isn't a normal question.
It's not, Why do you want to hug and kiss and wrestle and swing that child up into the air? That's a silly question for normal folk.
It's not, Why do you lift that flower to your nose and sniff?
Or, Why do you blink when someone tosses something at your face?
Or, Why does the earth spin in only one direction?
If you're still three years old, you can ask those questions. But after awhile, you figure out that life is what it is. Humans are what they are. Why? Just because. That's why.
I'm a little amused at myself today. I've spent so much time in three-year-old brain (a generally good place to be since so much of the grown up world can't answer the question Why? when they ought to know the answer) that I forgot that sometimes, "Just because" is the answer.
Why do you smile when you're happy? Just because.
Why do you cry when you're happy? Just because.
Why do all the puppies sleep in a pile like that? Just because.
Why is the grass green?
Why is it sunny only in the daytime?
Why is grandma old?
Why must you stomp in the puddles?
Just because just because just because.
The particulars have answers.
But some things are the way they are just because.
And why do I want to go to school? At my age? For a degree that has no obvious practical application? Just because. Grownup brain can tell you all the particulars, but the particulars answer a different question. The answer to, How? is in the particulars. The answer to, Why? is just because.