This study examines the profound philosophical and empirical question of knowledge fragility-the vulnerability of human cognitive representations to error, distortion, revision, and falsification from integrated cognitive psychological and neurobiological perspectives. Drawing on phenomenological qualitative methodology, the study conducted in- depth interviews with twenty-six participants including academic researchers, clinical psychologists, philosophers of science, and individuals who had experienced significant 'knowledge ruptures' moments of discovering that longstanding beliefs or certainties were false. The study documents how participants understand, experience, and respond to the fragility of their own knowledge, exploring the cognitive mechanisms underlying false knowledge, the neurobiological substrates that both enable and constrain learning and unlearning, and the psychological and social consequences of recognising knowledge's contingency. Findings reveal that knowledge fragility is experienced as simultaneously threatening and generative: threatening to individual identity, professional authority, and social cohesion, but generative of intellectual humility, epistemological flexibility, and creative innovation. The study identifies 'epistemic resilience'-the capacity to hold knowledge lightly, recognise its contingency, and revise it in response to evidence as a developable cognitive disposition with significant educational, clinical, and scientific implications. Recommendations address epistemic education, scientific communication practices, and psychological support for individuals experiencing worldview-disrupting knowledge revisions.