This is literally the point of ingsoc in 1984 btw. It is not that Big Brother is watching or they have cameras, it was the control over language. The book is about fascism as a linguistic technique, not a style of government. "Bad" becomes "ungood" and eventually as said in the book will drop the "un" so that it literally becomes impossible to describe something undesirable. It becomes impossible to describe the conditions of your unfreedom. The climax with the torture and the very end is not Winston being brainwashed or something but rather accepting that the Party really is a more reliable source of information, because they are: Winston has just discovered the dissidents were probably fake all along. If even your dissident thoughts and words originate within the Party, and you hate the Party, then why trust those dissident thoughts? The idea that two and two is four is just as much Party propaganda as the idea that it is five. So really, who knows?