Why is Theodore Dreiser considered a major American naturalist writer?

Theodore Dreiser is considered the preeminent American practitioner of naturalism, a literary movement that applied scientific principles—specifically a Darwinian view of nature—to the study of human behavior.12

He earned this distinction by replacing Victorian notions of propriety with an unflinching, objective presentation of reality. Influenced by the philosophies of Herbert Spencer and scientific thinkers, Dreiser’s work is defined by several key naturalistic tenets:1

• Scientific Determinism: He portrayed human beings as largely helpless, driven by instinctual urges and social forces beyond their control.23
• Environmental and Social Focus: His novels, such as Sister Carrie and An American Tragedy, explore the harsh realities of industrializing America, depicting characters struggling against economic pressures and social hierarchies.134
• Unbiased Observation: Dreiser approached his characters as a detached experimenter, documenting their lives without moral judgment, even when portraying transgressions against conventional sexual or social morality.24

By treating his characters as specimens shaped by heredity and environment, Dreiser elevated the American novel to a new level of psychological and social realism.24