One of the main characteristics of Literary Naturalism is the belief that man behaves in accordance with the laws of nature. Instinct and inherited traits, then, would drive his actions more than would free will. A second belief related to this first one is the idea that man is at the mercy of his environment. With this idea in mind, man reacts to what happens around him as opposed to drives it. Again, free will is not a factor in determining what happens in his life.
The tone of Naturalistic works is usually distant and non-judgmental. The author presents himself or herself as an objective observer, similar to a scientist taking note of what he or she sees. The Naturalistic writer believes that truth is found in nature, and thus is consistent. Everything follows preordained principles, patterns, and rules. Naturalistic works are character-driven more than plot-driven. The focus is on human nature, a phenomenon that is predictable. Skinnerian principles of learning through conditioning and the Darwinian hierarchy of the survival of the fittest are the underlying themes involved in shaping the human character.
Naturalism as a literary movement was especially popular in America from 1880 - 1920. Naturalism applies scientific principles of objectivity and detachment to the study of human beings so that the characters in the story may seem like the subjects of scientific case studies. Both Darwinism's concept of natural selection and Freud's concepts of psychology influenced the movement, so these principles may be used to explain the actions of a character. For example, in Jack London's "To Build a Fire," the human character is not even named, and his foolish mistakes are dispassionately contrasted with the more productive actions of his dog. Life is presented as deterministic or even mechanistic since heredity and environment control human actions rather than free will. For example, in Bret Harte's "The Luck of Roaring Camp," despite the men's efforts to improve themselves, their camp and the baby they have reformed for are washed away in a flood. Naturalism often depicts man in conflict with nature, society, or himself. The main characters in Naturalism are usually of the lower socioeconomic classes and often don't have a strong moral compass. The moral failings of individuals or society as a whole, however, are considered dispassionately. The tone is often detached, emotionless, and scientific. When it comes to diction, ugly and unpleasant words may be chosen rather than lyrical or elegant ones. In descriptive passages, an excessive amount of detail may appear, but the arrangement will be informal, even chaotic, in order to show that society and nature are governed by random forces. Artificial or optimistic plot structures are avoided and the action seems more of a "slice of life" than an arc in which can result in characters who change, grow, and develop.
Although Naturalist writers strove for a degree of scientific objectivity in their work, it is fair to say that a fairly deep-rooted pessimism is often obvious in their writings, engendered by their conviction that man is forever at the mercy of forces that he cannot ultimately control: the effects of heredity and/or environment. These forces are often seen to contribute to the downfall of many characters in these stories. In older, and more romantic terms, such forces might have been construed as a divine and supernatural fate; the Naturalist writers preferred to think in terms of biological, scientific determinism.
Concomitant with the pessimism often on display in the work of Naturalist writers is the element of violence, in keeping with the Naturalist stress on primitive instincts and life as a a continual struggle. Characters are often rough-hewn and brutish, like Frank Norris's McTeague; dogs and wolves fight to the death in Jack London's Call of the Wild and White Fang, and so on. Violence and pessimism, then, are also characteristics of the work of Literary Naturalists.