In the story it says that Winston doesn`t understand the why, but later on in the book, he finds out. Explain the problem with not understanding the why.

Winston doesn't understand why the Party does what it does. He understands how: the brainwashing, fear, thought police....but he struggles to understand the underlying reasons. What does the party hope to accomplish with a depressed, conformist, angry population? Winston finally understands, through torture, that it is simply perpetual power and control that the party wants.