Political language -- and with variations this is true of all political parties, from Conservatives to Anarchists -- is designed to make lies sound truthful and murder respectable, and to give an appearance of solidity to pure wind.
The great enemy of clear language is insincerity. When there is a gap between one's real and one's declared aims, one turns as it were instinctively to long words and exhausted idioms, like a cuttlefish spurting out ink.
George Orwell, "Politics and the English Language", 1946
Doublethink means the power of holding two contradictory beliefs in one's mind simultaneously, and accepting both of them. . .
Doublethink lies at the very heart of Ingsoc, since the essential act of the Party is to use conscious deception while retaining the firmness of purpose that goes with complete honesty. To tell deliberate lies while genuinely believing them and to forget any fact that has become inconvenient, and then, when it becomes necessary again, to draw it back from oblivion for just so long as it is needed, to deny the existence of objective reality and all the while to take account of the reality which one denies - all this is indispensably necessary. Even in using the word doublethink it is necessary to exercise doublethink. For by using the word one admits that one is tampering with reality; by a fresh act of doublethink one erases this knowledge; and so on indefinitely, with the lie always one leap ahead of the truth. Ultimately it is by means of doublethink that the Party has been able - and may, for all we know, continue to be able for thousands of years - to arrest the course of history..."
from http://www.orwelltoday.com/doublethink.shtml