why is the "mutability of the past" the "central tenet of INGSOC"? 1984

The mutability of the past is the central tenet of Ingsoc.

Because mutability of the past allows the party to follow a past that is whatever the party chooses to make it. The Party has control of the records, the people (their minds), ect., they can do what they want and no one can interfere. The mutability of the past is the ability to rewrite history and have people believe the way you've written it is the way it really happened. Our history textbooks do this all the time....... history is being rewritten as we speak.