Lifespan psychology: In honor of Johann Nicolaus Tetens (1736-1807)

The historical roots of lifespan psychology are traced back to Johann Nicol aus Tetens (1736-1807), a philosopher and psychologist of the era of Enligh tment. Specifically, we compare passages from Tetens' main oeuvre, publishe d in 1777, "Philosophical investigations about the human soul and its devel opment", with tenets and contents of contemporary lifespan psychology. Comm unalities comprise the emphasis on the entire life span, the formal definit ion of the scientific rationale of developmental psychology as description, explanation, and optimization of human ontogenesis, plasticity as its esse ntial characteristic, the distinction between person-centered and variable- centered research strategies, the fundamental significance of interindividu al differences, the intertwined nature of gains and losses, and the constit utive but historically variable function of culture in the regulation of de velopment. Tetens' view of absolute versus relative capacities closely rese mbles modern two-component models of intellectual development, such as Gf/G c theory or the model of mechanics and pragmatics of cognition. Tetens is r ightfully regarded as the founder of lifespan psychology; his dynamic notio n of development contains all central elements of modern lifespan theory. Tetens shows himself to be a true giant among the precursors of development al psychology. Neither before nor since Tetens (1777) has the true program of human developmental psychology been so impressiveley formulated. (Reiner t, 1979, S. 211).