I do not tell lies. Mother used to say that this was because I was a good person. But it is not because I am a good person. It is because I can’t tell lies.

Christopher explains that he cannot tell lies because telling lies is illogical. A lie, he reasons, means you say something that happened that didn’t happen, which violates logic since only one thing ever happens at a particular time and place. Christopher believes his inability to lie doesn’t relate to his character, but to his sense of order and truth. The story shows otherwise, since Christopher uses truth to establish trust with people, as seen in his interactions with strangers like Mrs. Alexander, and truth becomes the way in which he develops relationships with people.

People say that you always have to tell the truth. But they do not mean this because you are not allowed to tell old people that they are old and you are not allowed to tell people if they smell funny or if a grown-up has made a fart. And you are not allowed to say, "I don't like you," unless that person has been horrible to you.

Christopher explains one of his “Behavioral Problems”—saying things that most people think rude. While he’s instructed to always tell the truth, he observes that this rule only applies to certain instances. Even though Christopher would feel more comfortable in a world of straightforward and logical truth, he understands that world doesn’t exist. Truth—and honesty—consist of plenty of gray area, which Christopher’s logical mind struggles to navigate. In turn, the people who care for Christopher struggle to navigate these gray areas with him, which leads to major conflict in the novel.

This is called a white lie. A white lie is not a lie at all. It is where you tell the truth but you do not tell all of the truth.

In his logical mind, Christopher defines a white lie in a way that suits his thought process. Christopher works out clever ways to reconcile his actions and words through logic, since he still wants to investigate Wellington’s murder but has promised his father he wouldn’t. Truth and honesty play an important role in the book, especially in the relationship between Christopher and his father. They both bend the truth to meet their ends, so both carry blame for the issues that arise between them.

It’s bloody hard telling the truth all the time.

Here, Christopher’s father attempts to help Christopher understand why he lied about killing Wellington. While Christopher can’t tell anything but the truth—even if it involves white lies—Christopher’s father struggles telling the truth. Christopher’s father lies about Christopher’s mother because he feels like he has no choice. Upon confessing about Wellington’s death, he asks Christopher to understand that “life is difficult,” forcing choices to not tell the truth sometimes. He hopes Christopher can understand the reasoning behind this reality of life.

You have to learn to trust me … And I don’t care how long it takes…

After he sees the damage his lies cause with his relationship with Christopher, Christopher’s father reveals his determination to win back Christopher’s trust despite the realities of life. To Christopher, honesty has primacy. He depends on people telling him the truth to enable him to establish trust with them emotionally. Yet Christopher needs to live in the real world, a world in which truth is neither black nor white. Christopher’s father wants to heal their shattered relationship any way he can.