For what cause, reason, or purpose.
The word 'why' is correct and usable in written English. You can use it when asking a question or when expressing puzzlement, surprise, or doubt. Example sentence: Why did you decide to take that route?.
It is easy to see why.
It is not hard to see why.
Why so?
One can see why.
The question is why.
But why now?
Why don't they?
I mean, why not?
And why stop there?
"Ask yourself: if I were a Chinese spy, why wouldn't I have flown directly into Beijing?
Why would it?
I love the desktop app, it’s always running on my Mac. Ludwig is the best English buddy, it answers my 100 queries per day and stays cool.
Cristina Valenza
Retail Lead Linguist @ Apple Inc.