1984, O'Brien proposes a doctrine to Winston...

• What role does the doctrine play in maintaining the system of oligarchical collectivism?

The doctrine that O’Brien proclaims to Winston in this passage, plays an important role in maintaining the system of oligarchical collectivism because he is telling Winston, that since he has not fully come to a conclusion like everyone else that there is no other way but to conform, then he will drive himself insane trying to stop what has already been deemed unstoppable. O’Brien says to Winston, “You believe that reality is something objective, external, existing in its own right. You also believe that the nature of reality is self-evident. When you delude yourself into thinking that you see something, you assume that everyone else sees the same things as you. But I tell you, Winston, that reality is not external. Reality exists in the human mind, and nowhere else. Not in the individual mind, which can make mistakes, and in any case soon perishes; only in the mind of the Party, which is collective and immortal.” In telling Winston that reality is created in the mind of the Party and not the individual, he clearly lays out the premier idea of oligarchical collectivism, the idea that everything exists to benefit the party, primarily Big Brother. Winston is in every way correct in his oppositional thinking, but is greatly out numbered.
The doctrine’s purpose is to persuade Winston to forget about the system ever changing because it will never die and will only get stronger over time, whereas he will only grow weaker, mentally and physically, because it is extremely hard for a single person to change a reality for everyone.

• What role does the doctrine play in Winston’s fate at the end?

The ending of 1984, is indeed true to the saying, “If you can’t beat them, then join them.” After battling with his internal struggle of holding his values and morals for a good cause, he can no longer resist the Party that he is very much apart of. Instead of secretly hating them, he then openly shows his conformity with a single smile. He finally realizes that life is much easier accepting the way things are instead of fighting it all by yourself.
To me, the doctrine foreshadows Winston’s fate in a sense, because at the closing of the novel, Winston’s view of reality that was supposed to exist in its own right, did in fact perish because this view only existed in his mind, and the reality of the Party was again victorious and has shown once again its immortality to yet another who was in disbelief.
He gazed up at the enormous face. Forty years it had taken him to learn what kind of smile was hidden beneath the dark moustache. O cruel, needless misunderstanding! O stubborn, self-willed exile from the loving breast! Two gin-scented tears trickled down the sides of his nose. But it was all right, everything was all right, the struggle was finished. He had won the victory over himself. He loved Big Brother. (Part 3, Chapter 6)