"On the other hand, ethnic psychology must always come to the assistance of individual psychology, when the developmental forms of the complex mental processes are in question"

Wilhelm Wundt underscores the necessity of integrating ethnic psychology with individual psychology when seeking to understand the developmental forms of complex mental processes. While individual psychology often focuses on the workings of the mind from the perspective of each person, examining personal experiences, motivations, and behaviors, it alone cannot illuminate every facet of human mental development. This is especially true for the more intricate or layered psychological phenomena, such as language, myth, and shared cultural practices.

Ethnic psychology, what today we might call cultural or social psychology, provides vital context. It explores how groups of people, shaped by shared history, language, traditions, and collective norms, influence the formation and evolution of mental processes. Many complex mental functions, like moral judgment, aesthetic appreciation, or the ability to use and understand language, do not arise solely within the confines of an isolated individual. Instead, they develop and transform through sustained participation in social and cultural life. Culture gives shape to cognition, sets boundaries for emotion, and offers symbols and meanings that the individual mind internalizes, modifies, and communicates.

For example, language acquisition or the development of ethical reasoning cannot be thoroughly grasped by only examining the cognitive faculties of a single child. The social environment, the linguistic and moral traditions handed down across generations, play indispensable roles. Wundt argues that true comprehension of how complex psychological processes form and mature requires us to look beyond the individual, to the broader, collective psychological patterns that manifest over time within communities. Ethnic psychology thus becomes a partner field to individual psychology, enriching and completing our understanding of the psyche’s growth. Without this mutual assistance, investigations of mental development risk remaining fragmented and incomplete, unable to account for the source and richness of higher cognitive and emotional life.