During centuries, the loss of spontaneous cardio-pulmonary function was found to predict permanent non-functioning of the "organism as a whole", therefore serving adequately as a criterion of death, but during the era of Intensive Care, there was a shift to brain-oriented definitions of death, ie, the irreversible cessation of brain functions, started to be considered as the main reason for cessation of functioning of the "organism as a whole". A concept or definition of death is related to the question: What is it "about human life, which is irreplaceable by any artifice, and that its loss is so essential, that the individual who loses it ought to be called dead?" Further work has been centered on how much of the brain needs to be dead, before a person can be declared dead on neurological grounds: "whole brain", "brainstem death" ("brain as a whole") and "higher brain" formulations of death. These brain-oriented formulations of death are discussed and criticized, with the conclusion that although there is only one function, irreplaceable, which characterizes the human being: the "content" of consciousness, society is not yet prepared to define, diagnose and accept a "content" of consciousness-based standard of death, when this function is lost in isolation in PVS, advanced forms of dementia and anencephalics. I propose a concept of death that excludes those states taking in consideration the basic mechanisms of consciousness generation in human beings: "The irreversible loss of consciousness, considering both its capacity and its content". This definition of human death takes consideration as hallmarks, both components of consciousness which are essentially significant to the nature of man, to provide the functioning of the "organism as a whole".