Fragmentation as a drive toward a replicability crisis

The replicability crisis that emerged in psychological science during the early 21st century revealed methodological deficiencies and structural problems rooted in the discipline's historical development. This manuscript argues that psychology's fragmentation created conditions that amplified vulnerabilities to replicability failures. Unlike physics or biology, which achieved theoretical integration despite initial diversity, psychology maintained fundamentally incompatible research programs throughout its 150-year history, preventing cumulative knowledge building. We trace this trajectory from psychology's founding pluralism through behaviorist-cognitivist conflicts to neuroscientific reductionism during the Decade of the Brain, demonstrating how fragmentation into isolated subdisciplines with divergent methodological standards, weak constraining theories, and insufficient cross-disciplinary dialogue enabled questionable research practices to proliferate unchecked. Large-scale replication projects confirmed these vulnerabilities with effect sizes systematically inflated. However, we distinguish fragmentation fromhealthy theoretical pluralism, arguing that psychology's diverse phenomena legitimately require multiple levels of explanation. The path forward demands a programmatic theoretical development through three complementary strategies: interdisciplinary testing that subjects claims to multi-method scrutiny, mathematical formalization that constrains predictions and reduces interpretive flexibility, and open science infrastructure supporting collaborative evaluation and metascientific feedback. These approaches research communities, transforming psychology from a collection of isolated fields into a cumulative sciencewhere theory provides frameworks for interpreting reality.