Risk prediction is one of the central goals of medicine. However, ultimate prediction-perfectly predicting whether individuals will actually get a disease-is still out of reach for virtually all conditions. One crucial assumption of ultimate personalized prediction is that individual risks in the relevant sense exist. In the present paper we argue that perfect prediction at the individual level will fail-and we will do so by providing pragmatic, epistemic, conceptual, and ontological arguments.
Keywords: Individual risk; Ontology; Philosophy; Prediction; Reference class.