The term naturalism describes a type of literature that attempts to apply scientific principles of objectivity and detachment to its study of human beings. Unlike realism, which focuses on literary technique, naturalism implies a philosophical position: for naturalistic writers, since human beings are, in Emile Zola's phrase, "human beasts," characters can be studied through their relationships to their surroundings. Zola's 1880 description of this method in Le roman experimental (The Experimental Novel, 1880) follows Claude Bernard's medical model and the historian Hippolyte Taine's observation that "virtue and vice are products like vitriol and sugar"--that is, that human beings as "products" should be studied impartially, without moralizing about their natures. Other influences on American naturalists include Herbert Spencer and Joseph LeConte.Through this objective study of human beings, naturalistic writers believed that the laws behind the forces that govern human lives might be studied and understood. Naturalistic writers thus used a version of the scientific method to write their novels; they studied human beings governed by their instincts and passions as well as the ways in which the characters' lives were governed by forces of heredity and environment. Although they used the techniques of accumulating detail pioneered by the realists, the naturalists thus had a specific object in mind when they chose the segment of reality that they wished to convey.
In George Becker's famous and much-annotated and contested phrase, naturalism's philosophical framework can be simply described as "pessimistic materialistic determinism." Another such concise definition appears in the introduction to American Realism: New Essays. In that piece,"The Country of the Blue," Eric Sundquist comments, "Revelling in the extraordinary, the excessive, and the grotesque in order to reveal the immutable bestiality of Man in Nature, naturalism dramatizes the loss of individuality at a physiological level by making a Calvinism without God its determining order and violent death its utopia" (13).