What is the definition of Death?

You can find an interesting discussion of the definition of 'death' in Peter Singer's "Rethinking Life and Death." There is a helpful discussion in the first chapter about "The Ad Hoc Committee of the Harvard Medical School to Examine the Definition of Brain Death." This committee proposed in 1968 to "redefine" death so that a person who has suffered irreversible loss of all brain function counts as dead, even if the person is still breathing with the help of a respirator. While this proposal met with little resistance, people are much less inclined to say that someone in a persistent vegetative state is dead--even if there is an irreversible loss of consciousness.