How did Theodore Dreiser's novels reflect the ideas of naturalism?

Theodore Dreiser’s novels are considered the peak of American naturalism, a movement that applied scientific determinism to literature. His work reflects this philosophy in several key ways:1

• Scientific Determinism: Influenced by thinkers like Herbert Spencer, Dreiser portrayed human beings as largely helpless, driven by instinctual urges and social forces beyond their control. His characters often struggle against an unequal contest between the strong and the weak.2
• Unflinching Realism: Moving away from Victorian notions of propriety, Dreiser provided a grittily factual "slice of life" that documented urban environments and social pressures without moral judgment.31
• Environment and Heredity: His characters are depicted as products of their backgrounds and environments, often facing oppressive social or economic conditions. For example, Sister Carrie presents a heroine who transgresses conventional morality without facing traditional punishment, while An American Tragedy offers a searing indictment of materialism and the American dream.145
• Detached Observation: Like the experimental approach championed by Émile Zola, Dreiser’s writing functions as a study of human behavior, analyzing the psychological disintegration of characters like George Hurstwood with clinical detail.415