It is clear that in this terrifying novel we are presented with a surveillance society where every move of every citizen could be monitored and reported, with tragic consequences for that citizen should it be deemed that they are involved in what is termed "thought crime." Lack of rebellion is thus achieved by creating a society of absolute fear - if you could be watched at any moment, you could be reported and then taken away and punished for any deviant behaviour. Note how this claustrophobic atmosphere is established very early on in the novel:
The black mustachio'd face gazed down from every commanding corner. There was one on the house-front immediately opposite. BIG BROTHER IS WATCHING YOU, the caption said, while the dark eyes looked deep into Winston's own... In the far distance a helicopter skimmed down between the roofs, hovered for an instant like a bluebottle, and darted away gain with a curving flight. It was the police patrol, snooping into people's windows. The patrols did not matter, however. Only the thought Police mattered.
With the slogan of Big Brother, the citizens of Oceania are constantly reminded that there every move is being watched and inspected for any form of rebellious behaviour. We are presented with a world where every second is observed and there is always the tremendous fear of being taken away by the Thought Police to the ironically named "Ministry of Love."
The root of surveillance and knowing everything comes from the fact that the Party does a good job of destroying the private realm. In ensuring that there is no private domain and that everything is in the realm of the public, Big Brother is successful in making sure that there can be no solidarity towards one another, making everything submissive to the will of the Party. The detection of Thoughtcrimes helps to bring this out in full force. The ability to conduct surveillance against individual thoughts is another way that one cannot even be loyal to one's own thinking. In the end, this results in complete and absolute totality in favor of the state. The use of technology is a way in which the Party is able to ensure that total submission to the state is present. In the process it eliminates the realm of the private to ensure that there can only be one force in the form of the state.