Winston is stubborn in believing that the Party controls the past. He insists that the Party cannot control peoples' memories, and therefore, the past still exists in the minds of humans.

O'Brien: 'You are no metaphysician, Winston. Until this moment you had never considered what is meant by existence. I will put it more precisely. Does the past exist concretely, in space? Is there somewhere or other a place, a world of solid objects, where the past is still happening?'
Winston: 'No.'
O'Brien: 'Then where does the past exist, if at all?'
Winston: 'In records. It is written down.'
O'Brien: 'In records. And?-'
Winston: 'In the mind. In human memories.'
O'Brien: 'In memory. Very well, then. We, the Party, control all records, and we control all memories. Then we control the past, do we not?'
Winston: 'But how can you stop people remembering things? It is involuntary. It is outside oneself. How can you control memory? You have not controlled mine!'