The tone of the omniscient narrator in "To Build a Fire" is impersonal and detached, which is typical of Naturalist literature. The narrator's lack of emotion reflects the indifference of the natural world toward humankind—like the dog, the narrator is not particularly interested in the man's plight and maintains a dispassionate attitude toward him throughout the story.
The tone of the story is also occasionally judgmental, with the narrator declaring early on what the man's fatal flaw is:
The trouble with him was that he was without imagination. He was quick and alert in the things of life, but only in the things, and not in the significances.
The judgmental tone in this passage foreshadows the fact that the man's lack of imagination will get him into serious trouble later on in the story, when he fails to consider the danger of building his fire beneath a tree. The judgmental tone also makes "To Build a Fire" a fundamentally cautionary tale—in this story, London is advancing an argument about the inadequacy of human reason and pride in the face of nature. The detached, impersonal tone therefore underscores the cautionary element of the story, allowing London to impart narrative wisdom from a relatively neutral standpoint.
