The answer are: He uses parody to show how dictators deflect blame to others;
He uses reversal to show that dictators do not abide by their principles.
The author of Animal Farm, George Orwell, wrote the novel with the intention of criticizing the regime to which Russia was subjected by Stalin. Orwell himself was a democratic-socialist.
The pigs take over the farm where they live with other animals after expelling the human who was its owner. They (the pigs) at first preach and work for equality and the animals are sure their lives will be transformed for the better.
However, the pigs, especially Napoleon, realize how their position as leaders brings them many advantages and, in order to stay in power, grow more controlling and begin to lie to get the other animals to do their bidding.
In the excerpt mentioned in the question, Napoleon got rid of another pig, whose ideas were essentially good and served their original purpose of equality. Napoleon slowly ascends to a position of a dictator, while he has those who work close to him, such as Squealer, manipulate the animals by lying to them. He puts the blame on others and changes his mind (doesn't abide by his principles) whenever it is convenient. For instance, in their society, there used to be 7 commandments to be followed by the animals. But, as the pigs grew more powerful and similar to humans, the commandments are changed to justify their actions:
- No animal shall kill any other animal
becomes
- No animal shall kill any other animal without a cause.
