"The most generally held concept of propaganda is that it is a series of tall tales, a tissue of lies, and that lies are necessary for effective propaganda...This concept leads to two attitudes among the public. The first is: "Of course we shall not be victims of propaganda because we are capable of distinguishing truth from falsehood." Anyone holding that conviction is extremely susceptible to propaganda, because when propaganda does tell the "truth", he is then convinced that it is no longer propaganda; moreover his self-confidence makes him all the more vulnerable to attacks of which he is unaware.
For a long time propagandists have recognized that lying must be avoided...It seems that in propaganda we must make a radical distinction between a fact on the one hand and intentions or interpretations on the other; in brief, between the material and moral elements. The truth that pays off is in the realm of facts. The necessary falsehoods, which also pay off, are in the realm of intentions and interpretations... Propaganda by its very nature is an enterprise for perverting the signifigance of events and of insinuating false intentions... First of all, the propagandist must insist on the purity of his own intentions and at the same time, hurl accusations at the enemy. But the accusation is never made haphazardly or groundlessly. The propagandist will never accuse the enemy of just any misdeed; he will accuse him of the very intention that he himself has and of trying to commit the very crime that he himself is about to commit."
-from Jacques Ellul's "Propaganda: The Formation of Men's Attitudes"