This was first published in 2000: What is brain death? At what point does a human life begin or end? Thomas Russell presents his concept of death, viewing death as death of the organism as a whole and answering the question "what is death?" with an examination of what constitutes life. Drawing on philosophical arguments, Russell argues that all current concepts of brain death are conceptually inadequate, but a new concept of death, applicable to all living entities, can encompass the traditional criteria and tests for death and does not entail any significant operational changes in the way in which death is diagnosed. From an historical review and examination of concepts of death, Russell considers key topics including: different brain states; conditions for life; biological concepts; and the moment of death.