How does Newspeak help the Party to maintain control in Part One of 1984?
Newspeak was developed by the Party to replace Oldspeak, the traditional English language. In Part One of the novel, Winston's friend, Syme, explains that Newspeak involves "cutting the language down to the bone" so that all "vagueness" and "useless shades of meaning" are destroyed.
But Newspeak is about more than clarifying meaning. Its purpose, according to Syme, is to "narrow the range of thought" so that thoughtcrime becomes impossible. This is based on the idea that a person cannot feel discontent with the Party if there are no words to express this attitude.
For the Party, then, controlling language is the key to controlling individual thought. If they can remove the words which promote nonconformity and free-thinking, their absolute control over the people of Oceania is guaranteed. This explains why Syme says that "the Revolution will be complete when the language is perfect."
Newspeak is a way of deconstructing the language to a point that no original thought is needed to express your elements of conversation. Instead of "amazing", "incredible", and "scintillating" a Newspeak speaker would use the word "Doubleplusgood" to indicate that something was an exemplified form of "good".
Getting rid of original thought--no books, no debates, no free thought--makes it easy to move into brainwashing and mind control of masses of people.
This is one reason why in governments who attempt to squash Democracy, the first thing the controlling party does is get rid of the teachers and free-thinkers since these are the people who are able to motivate others to stand up for themselves and for what is right.