Goldstein's answer to this question takes up a significant number of pages within 1984 and serves as one of the most significant political analyses to come out of Orwell's books, discussing from both a theoretical and a practical perspective the rationale by which the Party maintains power and control. It would be impossible to do full justice to that analysis here.
First, note that the Party's central task is maintaining a stable and self-perpetuating hierarchical structure. Secondly, note that, according to Goldstein, the nations of Oceania, Eastasia, and Eurasia exist in a state of perpetual warfare with one another (a war which cannot actually be won by any of the combatants and is at this point, in reality, being fought mainly to perpetuate itself). These two factors are not incompatible with one another: in fact, that state of perpetual warfare is a critical factor which allows the Party to maintain its grip on larger society.
Ultimately, paradoxical as it might seem, one of the...
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