'Animalism' is the name given to the basic tenets expounded by Old Major in his speech to the animals when he addressed them in the big barn. It was developed into a complete system of thought by Snowball, Napoleon and Squealer, the pre-eminent pigs on the farm. The system entailed rules and principles the animals had to follow to ensure that all the animals were treated as equals and that they did not become like the oppressive humans.
The pigs generally ignored these principles and manipulated the rules to achieve their own agenda, which was to gain privilege for themselves and live lives of luxury and comfort. The first signs of the pigs' intent was when the five buckets of milk and the windfall apples were claimed for their exclusive use. When some of the animals complained about this, Squealer went around to convince them why it was necessary to have these resources:
"Comrades!" he cried. "You do not imagine, I hope, that we pigs are doing this in a spirit of selfishness and privilege? Many of us actually dislike milk and apples. I dislike them myself. Our sole object in taking these things is to preserve our health. Milk and apples (this has been proved by Science, comrades) contain substances absolutely necessary to the well-being of a pig. We pigs are brainworkers. The whole management and organisation of this farm depend on us. Day and night we are watching over your welfare. It is for YOUR sake that we drink that milk and eat those apples. Do you know what would happen if we pigs failed in our duty? Jones would come back! Yes, Jones would come back! Surely, comrades," cried Squealer almost pleadingly, skipping from side to side and whisking his tail, "surely there is no one among you who wants to see Jones come back?"
This type of rhetoric became common and, since Squealer was such a brilliant talker, he became the pigs' mouthpiece. It was his task to convince the animals that they were at fault in thinking that the pigs were seeking to provide themselves unfair advantages. The threat of Jones returning was constantly used to remind the animals that the pigs had a noble purpose and to make them afraid.
Whenever the pigs adopted behavior that went against the principles of Animalism, they would alter the commandments written on the barn wall. The commandments were, essentially, a summary of the basic tenets of Animalism. So it was that after Snowball had been banished, the Sunday Meetings were stopped. Napoleon explained that they were unnecessary and that the pigs would meet and arrange schedules for the week ahead. Debate was not necessary anymore. When four young pigs wanted to protest, Napoleon's vicious dogs growled menacingly, causing them to immediately shut up. Squealer, again, explained the necessity of this decision, stating that animals sometimes make the wrong decisions. He denigrated Snowball and spoke of him as if he was an enemy to what they wished to achieve on the farm.
The general animal populace lacked the intelligence to challenge Squealer's explanations and he went unchallenged. Their general ineptitude to argue and Benjamin's indifference, allowed the pigs to assume total control. This power was abused. When the pigs moved into the farmhouse and slept in beds, they changed the commandment, 'No animal shall sleep in a bed' to 'No animal shall sleep in a bed with sheets,' to justify their actions. They were, however, the only ones who slept in beds. The other animals had to make do with sleeping in the barn.
Once again, Squealer went around to explain their decision:
"You have heard then, comrades," he said, "that we pigs now sleep in the beds of the farmhouse? And why not? You did not suppose, surely, that there was ever a ruling against beds? A bed merely means a place to sleep in. A pile of straw in a stall is a bed, properly regarded. The rule was against sheets, which are a human invention. We have removed the sheets from the farmhouse beds, and sleep between blankets. And very comfortable beds they are too! But not more comfortable than we need, I can tell you, comrades, with all the brainwork we have to do nowadays. You would not rob us of our repose, would you, comrades? You would not have us too tired to carry out our duties? Surely none of you wishes to see Jones back?"
Propaganda was used especially to demonize Snowball. He was held responsible for everything that went wrong on the farm. The pigs also used this argument to severely punish those who were supposedly colluding with him. At one stage Napoleon purged the farm of those who had been implicated in this regard. The dogs tore out the throats of those who were driven to confess. After the execution of so many animals, the remaining ones were absolutely distraught and terrified. The pigs had discovered another method to subdue and control the animals: extreme violence and brutality.
There are numerous examples of the pigs growing tyranny and the other animals' increasing fear and anxiety to challenge them. The pigs merrily adopted human habits and were remorseless. They, for example, again altered another commandment after the terrible executions. 'No animal shall kill any other animal' was adjusted to read: 'No animal shall kill any other animal without cause.' The animals understood then that the other animals were executed because they had colluded with Snowball to destroy the farm.
Throughout the novel, the general animal populace was deceived and misled by lies and deceit. Since they could not clearly remember the past, they accepted the pigs' versions of events. Boxer, for example, believed that Napoleon was always right and he easily accepted his explanations. In the end, these animals became mere pawns in the hands of the malicious and greedy pigs. Their lot was clearly engendered in the change made to a core principle of Animalism, which stated: 'All animals are equal' which was changed to the paradoxical and fatuous: 'All animals are equal but some animals are more equal than others.'