Language and Thought

Why is the ruthless totalitarian regime, described in Orwell’s novel purging Oldspeak and imposing Newspeak? What assumptions are being made about the relationship between language and thought?

He is suggesting to remove all the words that are not useful to us, words that are not a necessity, words we can go without and can still manage to communicate and understand if not used. An example given was the word 'bad' substituted with 'ungood' and excellent substituted with 'plus good'. Here, the word excellent isn't necessary to get a clear understanding, and one can understand 'plus good' instead. He is implying that the less words we know in a language, the less we think. The less we know, the less we understand and the less we think.   

This taking away of 'non-useful' words is also known as censorship. However, censorship can be considered bad because it puts limits on free speech and it alters the way we think. The narrower the language diction, the narrower the mind thinks.