Lies were how his father operated. He told the people fairy tales so they could sleep at night. (2.22)
Ah, the noble lie. It's when you lie to someone for their own sake to make them feel better. The problem with Willux's lie is that it eroded the Pures sense of empathy. He lied for their safety, but by doing so, he created monsters.
"That "lie," Hoppes continues, using air quotes, "has created the framework that allows the people to accept themselves, to be able to look themselves in the eye, to love each other, and to go on." (2.40)
Here, Hoppes reinforces Willux's lie. To him, Willux had to lie in order for the people inside the Dome to accept themselves.
"As if you don't have lies of your own already, Partridge […] If you're going to come clean, why don't you start with yourself?" (2.64)
The problem with Partridge exposing his father for being a liar is that Partridge is also a liar.
And Partridge has uncovered so many secrets—destruction, death, and so many layers of lies. He doesn't want to know any more of them. (6.97)
Partridge can't handle the lies he's been fed at this point—now, he feels like he's living a lie.
He's taken away their lie—the one that allowed them to function in the world around them. If you rob them of their lie, they'll self-destruct. (6.2)
So apparently that big lie that Willux told everyone was pretty much the glue that held the Dome together. Without it, the Dome starts to implode.
"No. Brave is what I'm doing now. Brave is ending the lie," he says, and an awful smile cracks at the edge of his mouth. "I've been a coward up until now." (10.17)
This is an example of how people inside the Dome feel about the lie: the only way to make up for their cowardice is to kill themselves. Death is a way to escape the lie.
And these dying people called him a liar, but Partridge couldn't tell whether they hated him because of the truth he told about his father or this new lie—marrying Iralene. (14.12)
Or maybe, people hate Partridge because he can't make up his mind. If he decides to preach the truth while simultaneously lying to everyone about his marriage, he really has no validity as a ruler.
How many lies will he have to offer up as a sacrifice to appease the people of the Dome? How many? (14.29)
Truisms can be true: "when first you practice to deceive, oh what a tangled web you weave."
"You're not telling the whole truth, which is lying." (33.19)
That's why they ask you to tell "the truth, the whole truth, and nothing but the truth" in a court of law. Anything less than the whole truth is still a lie.
"They were fairy tale versions of our lives. We loved ourselves in them. Each time he'd bring a new one to us, we'd savor it together." (35.14)
Iralene is so insanely tragic. She knows very little truth, which allows her to fall in love with Willux's lies… and his son.