Can you really narrow the range of thought by narrowing vocabulary, as the Party seeks to do? What does that mean for people with small vocabularies - would they think less? Why does the Party think so?
The original question had to be edited. The Party's position would indicate that one can narrow the range of thought by narrowing vocabulary. From a metaphysical point of view, this would make sense. If individuals lack the verbal skills to articulate their reality, then their reality remains indescribable. How does someone describe something when they lack the language to do so? Language is what forges solidarity with others. If one lacks language to describe their situation or condition in being, others cannot understand. Individuals are alienated and isolated from one another. This is certainly one end of the Party's motivation to replace language with a narrow scope of lexical focus. At the same time, if people lack language, then some type of communicative tool must be embraced. This communicative tool is present when the the Party advocates the use of Newspeak. In supplying a shared language that is generic and denies the presence of complexity in communication, then greater control can be exerted by those in the position of power. Messages can be guaranteed to be understood. There is little confusion because everyone shares the same linguistic mode of thought and communication. This helps to deny individuality and remove complexity in thought and articulation, specific goals of the Party and Big Brother as a leadership apparatus.
In terms of what the implications are for those with small vocabularies, it becomes evident that their voices become less significant. For those with smaller vocabularies, they are able to articulate less of their experiences and a smaller amount of their narratives. They become dependent on the linguistic means provided to them in order to communicate their experiences. It is here in which those who have smaller vocabularies are more dependent on Newspeak and thus on the Party. In terms of their thinking less, it would certainly be a logical condition to see that they think less. In any event, even if they thought more, they are unable to express it and thus their thinking has little tangible weight or merit. They cannot communicate their thoughts and thus are silenced by default. Orwell believed language to be power. In his mind, the control of language resulted in immense conditions of power. For this reason, the Party's control of language becomes significant in terms of their ability to consolidate and control their condition of power.