As the pigs gain more and more power over the farm, they use Squealer's fast-talking ability to convince the other animals that they are actually working for the common cause, not for their own gain. Every time there is a contentious issue, or something that seems to be unfair, Squealer appeals to their fear of Farmer Jones to confuse the issue:
"...as to the Battle of the Cowshed, I believe the time will come when we shall find that Snowball's part in it was much exaggerated... One false step, and our enemies would be upon us. Surely, comrades, you do not want Jones back?"
(Orwell, Animal Farm, msxnet.org)
No animal wants to return to the farm's past, even though they eventually forget if it was truly worse than the present situation. Squealer appeals to the common fear and hatred of humans, and uses slogans, rhetoric, and unashamed lies in his speeches. Because most of the animals have only short-term memories, and because there is no opposing viewpoint to cause debate, the animals have little choice but to accept his words as official truth.