Human life and death should be defined biologically. It is important not to conflate the definition of death with the criteria for when it has occurred. What is distinctively "human" from a scientific or normative perspective has nothing to do with what makes humans alive or dead. We are biological organisms, despite the fact that what is meaningful about human life is not defined in biological terms. Consequently, as in the rest of the realm of living beings, human beings die when they no longer function biologically as organisms. In contrast, a determination of exactly when death has occurred, required to serve various social purposes, combines social and normative considerations with biological facts.