The tone of the novel depends on Bigger's very particular and constantly changing worldview. The novel plays out through Bigger's eyes, and one of the book's central concerns is how Bigger's worldview interacts with the racist societal structures that control his life. The tone of the novel is thus determined by that interaction. The tone of the novel, with that in mind, is cynical and world-weary. Due to Bigger's tendency for action, the tone is also defiant, angry, and bold.
In Book 1, Bigger vaguely understands that the world is a game that white people win and Black people lose, and he seeks to succeed as much as possible within that system. He is unclear whether Black people deserve their position: "Why did he and his folks have to live like this? What had they ever done? Perhaps they had not done anything. Maybe they had to live this way precisely because none of them in all their lives had ever done anything, right or wrong, that mattered much." Bigger's worldview becomes much clearer after killing Mary, though, and thus the tone of the novel grows more brash and bold. With newfound clarity in Book 2, he states his new plan for life: "Act like other people thought you ought to act, yet do what you wanted." He finds white people to be a "great natural force" that he is incapable of stopping. The tone of the book is constrained, because of how much "how other people thought you ought to act" controls Bigger's life. But it is also profoundly reckless, because Bigger also feels that he is privy to no law because no law protects him, and so he can "do what [he] wanted."
By Book 3, the reader and Bigger are both entirely resigned to his fate. Bigger sees his death as a foregone conclusion, the inevitable result of his acting however he wanted. The tone of the book in these late sections is forlorn, contemplative, and austere, as Bigger considers his life alone in his cell. But even in the darkest moments at the end of the novel, Bigger rediscovers something close to hope and even forgiveness toward Jan. The tone then takes on a new kind of defiance, as Bigger gains an inner peace despite his upcoming death. Bigger's consolidating worldview creates the tone of the novel: Native Son starts out cynical but becomes bolder as Bigger grows more brash. Later, as Bigger wallows in prison, the tone follows his forlorn depression followed by his impossible hope.