I think people who know it's stealing, but are willing to download books anyway because of their personal risk/reward calculation (or perhaps they dislike the author and don't mind stealing from him!), have an intact moral compass: They know right from wrong.
I wonder about people who try to rationalize the crime of book-stealing away. Do they know right from wrong?
I won't judge people who decide to steal books, but I don't like those who try to argue it's not theft.