Lyra, the heroine of the novel, is, without a question, a regular and skilled liar. She lies about everything, from whether she's been on the Jordan College roof or not to eventually orchestrating the duel between Iorek and Iofur by telling Iofur that she's Iorek's dæmon. Initially, the novel treats Lyra's penchant for lying as a normal part of being a child, but as the novel progresses, it begins to suggest that lying is something to take seriously, especially if one wants to use lies to extract the truth or do the right thing. In this way, The Golden Compass portrays a person's lies and the intentions behind them as a useful way to gauge their relative morality.
When Lyra's story begins, her lies and deceits seem to have little consequence—the worst that happens is that she gets out of her sporadic and boring lessons, or she gets in trouble. This all begins to change when she witnesses something that shocks her to her core: she sees the Master of Jordan College, a man whom she thought was good, poison a decanter of wine intended for Lord Asriel. At this point, Lyra is introduced to the fact that she's not the only liar at Jordan College or indeed, in the world: other people are also busy lying and deceiving others as they go about their business and attempt to achieve their goals. Unfortunately for Lyra, the fact that she tips off Lord Asriel and he doesn't drink the wine sets off a series of events that ultimately culminates in discovering that Lord Asriel is one of the worst offenders when it comes to lying. Similarly, in a private meeting with another Scholar that takes place soon after Lyra witnesses the assassination attempt, the Master admits that he was trying to save Lyra from Lord Asriel and preserve her childhood and innocence for a while longer. While Lyra is never privy to this information, it allows the reader to see early on that there's more to one's actions than might initially meet the eye—a bad or deceitful act may actually be something good in the long run.
Lyra's identity as a liar becomes more complicated in the following weeks when, early in the morning before Lyra leaves Jordan College to live with Mrs. Coulter, a wealthy and glamorous woman, the Master gives Lyra an alethiometer—the titular golden compass which, if someone knows how to read it, will answer any question truthfully. For most people—that is, adults—learning to read the alethiometer takes years of study and the help of one of only a few reference books on the subject. Once Lyra figures out how the alethiometer is supposed to work, however, she's able to teach herself to read it without much help; she only occasionally asks clarifying questions about what the pictures on the compass face are. With this, the novel suggests that just as lying and pushing the limits as Lyra does are normal aspects of childhood, so too is the ability to effectively and intuitively ascertain the truth. Iorek confirms this when he suggests that Lyra's ability to read the alethiometer is likely similar to bears' innate ability to recognize deceit and trickery, a skill that humans used to have but have long since forgotten. This suggests that Lyra might lose the ability to read the alethiometer as she moves toward adulthood and thereby becomes what the novel suggests is more human.
With the help of the alethiometer, Lyra is able to channel her lies to do what she believes is the right thing and through doing so, develops a firmer and more nuanced view of what constitutes morality, good, and evil. The fact that it takes the combination of truth and deceit to do this suggests that lies aren't all bad—instead, intention and a sense of what's right or wrong on a grander scale is what matters. Importantly, however, the one thing that Lyra never questions—Lord Asriel's goodness and trustworthiness—leaves her susceptible to his manipulations and ultimately, ends in Lyra unwittingly leading her best friend, Roger, to his death at Lord Asriel's hands. Even in the hours before Lord Asriel moves to kill Roger, Lyra seems aware that he's nor a moral or trustworthy person. She feels hurt and betrayed that he's spent her whole life lying to her about being her uncle rather than her father, and suggests that a good, moral, truthful father would've shared this information and thanked her for bringing him the alethiometer, which Lyra believes she was supposed to do.
Following Lyra's betrayal of Roger and Lord Asriel's betrayal of Lyra, Lyra and Pan vow to do what they can to protect other children from dying like Roger did. Importantly, they decide to go it alone with only the help of the alethiometer. With this, the novel suggests that as Lyra moves on, it's important that she can both successfully lie and gain access to the truth. But more important than either of those things is learning how to ask the right questions—something that the novel suggests is the only way to truly understand the morality of one's actions.
Truth, Lies, and Morality ThemeTracker
Truth, Lies, and Morality Quotes in The Golden Compass
"I didn't have anything in mind, and well you know it," she snapped quietly. "But now I've seen what the Master did, I haven't got any choice. You're supposed to know about conscience, aren't you? How can I just go and sit in the library or somewhere and twiddle my thumbs, knowing what's going to happen? I don't intend to do that, I promise you."
Mrs. Coulter came into the bathroom to wash Lyra's hair, and she didn't rub and scrape like Mrs. Lonsdale either. She was gentle. Pantalaimon watched with powerful curiosity until Mrs. Coulter looked at him, and he knew what she meant and turned away, averting his eyes modestly from these feminine mysteries as the golden monkey was doing. He had never had to look away from Lyra before.
Indeed, Tony heard from gossip in pubs along the way that the police were making raids on houses and farms and building yards and factories without any explanation, though there was a rumor that they were searching for a missing girl. And that in itself was odd, considering all the kids that had gone missing without being looked for.
"Because, Iorek, listen: I got this symbol reader that tells me things, you see, and it's told me that there's something important I got to do over in that village, and Lord Faa won't let me go there. He just wants to get on quick, and I know that's important too. But unless I go and find out what it is, we might not know what the Gobblers are really doing."
Her first impulse was to turn and run, or to be sick. A human being with no dæmon was like someone without a face, or with their ribs laid open and their heart torn out: something unnatural and uncanny that belonged to the world of night-ghasts, not the waking world of sense.
"How do you do that?"
"By not being human," he said. "That's why you could never trick a bear. We see tricks and deceit as plain as arms and legs. We can see in a way humans have forgotten. But you know about this; you can understand the symbol reader."
"That en't the same, is it?" [...]
"It is the same," he said. "Adults can't read it, as I understand. As I am to human fighters, so you are to adults with the symbol reader."
"Yes, I suppose," she said, puzzled and unwilling. "Does that mean I'll forget how to do it when I grow up?"
"I think he's got an entirely different idea of the nature of Dust. That's the point. It's profoundly heretical, you see, and the Consistorial Court of Discipline can't allow any other interpretation than the authorized one. And besides, he wants to experiment—"
"To experiment? With Dust?"
"If he's got Dust and you've got Dust, and the Master of Jordan and every other grownup's got Dust, it must be all right. When I get out I'm going to tell all the kids in the world about this. Anyway, if it was so good, why'd you stop them doing it to me? If it was good, you should've let them do it. You should have been glad."
"We've heard them all talk about Dust, and they're so afraid of it, and you know what? We believed them, even though we could see that what they were doing was wicked and evil and wrong...We thought Dust must be bad too, because they were grown up and they said so. But what if it isn't? What if it's—"
She said breathlessly, "Yeah! What if it's really good..."