Quotes related to the slogan explain how the government of Oceania holds all of the power over its people.
The definition of "Doublethink" is an example of Big Brother's power over its citizens. Orwell describes "Doublethink" as "The power of holding two contradictory beliefs in one’s mind simultaneously, and accepting both of them." The government insists the contradiction makes sense. Orwell suggests that the way to control people is to ensure an "unending series of victories over your own memory" and individual thought.
The Party's slogan represents the essence of Doublethink. Each portion contains its opposite. At face value, the slogan does not make sense. However, the government wants its citizens to accept the contradiction as fact. Once they accept it, the people become easily pliable. A society is easier to control when its members are told that everything is fine and there are no problems. This is a reflection of the power that the government has over its citizens. By being reminded constantly that "ignorance is strength" or "freedom is slavery," no one questions anything. The ability to control how people think is one of the ways in which power is established. Doublethink enables.