Like much else in Animal Farm, deception is used to gain power. The pigs deceive the other animals about the past, convincing them that certain events did or did not occur. They deceive them as to the present, pretending that their situation is better than it really is. And they deceive the farm animals as far as plans for the future, ensuring them their dreams will come true. We see that superior intelligence is often used not to lead justly, but to deceive.
While the pigs are able to convince some of the animals of their lies, their attempt to deceive ultimately fails with most of the animals on the farm. Deception is not the main tool of power for the pigs.
While the pigs use many different forms of deception and lies, it is their ability to alter the past in the minds of the animals that is their most powerful tool of control.