Control the manner in which a man interprets his world, and you have gone a long way toward controlling his behaviour. That is why ideology, an attempt to interpret the condition of man, is always a prominent feature of revolutions, wars and other circumstances in which indiviuduals are called upon to perform extraordinary action. Governments invest heavily in propaganda, which constitutes the official manner of interpreting events.
Every situation also possesses a kind of ideology, which we call the 'definition of the situation', and which is the interpretation of the meaning of a social occasion. It provides the perspective through which the elements of the situation gain coherence. An act viewed in one perspectiv may seem heinous; the same act viewed in another perspective seems fully warranted. There is a propensity for people to accept definitions of action provided by legitimate authority. That is, although the subject performs the action, he allows authority to define the meaning.
It is this ideological abrogation to authority that constitutes the principal cognitive bias of obedience. If, after all, the world or the situation is as the authority defines it, a certain set of actions follows logically.
The relationship between authority and subject, therefore, cannot be viewed as one in which a coercive figure forces action from an unwilling subordinate. Because the subject accepts authority's definition of the situation, action follows willingly.
I was trying to get at this stuff a bit in this post.
The book is well worth a read btw, and deserves its reputation.