How does Orwell question the nature of authority and the nature of reality in "1984"?

Both of these passages come from Part One, Chapter 7, I read the book on-line, no page numbers available 

In 1984, the nature of authority and reality are shaped by the party.   

Reality 

"In the end the Party would announce that two and two made five, and you would have to believe it. It was inevitable that they should make that claim sooner or later: the logic of their position demanded it. Not merely the validity of experience, but the very existence of external reality was tacitly denied by their philosophy."

Authority

"The Party told you to reject the evidence of your eyes and ears. It was their final, most essential command. His heart sank as he thought of the enormous power arrayed against him, the ease with which any Party intellectual would overthrow him in debate, the subtle arguments which he would not be able to understand, much less answer. And yet he was in the right! They were wrong and he was right."