Alive, Dead or Otherwise (2 Letters) Re "Seeing Bogeymen in the Fog Around Brain Death" (Books, March 27): This appropriately scathing review of Dick Teresi's "The Undead" fails to address the foundational error of the book: the equivocation - either deviously purposeful or inexplicably ignorant - on the terms "human" and "life" and "human life." A heart in a cooler awaiting transplant is incontrovertibly human and alive, yet no one would argue that it is entitled to the legal and moral consideration that we reserve for human life. In contrast, a person with a clearly nonliving mechanical heart unhesitatingly receives that consideration. The difference? A functioning human brain and the emergent phenomenon it enables, a functioning human mind. Absent a functioning mind, or the possibility that nonfunction can be reversed, there is no human life in the legal or moral sense. There is no person. It then becomes unproblematic, with the appropriate permissions, to use that body's organs - still human and alive - for transplantation. Brian Zack, M.D. Princeton, N.J. Dick Teresi is aware that the history of medicine is full of atrocities and injustice (many stemming from the deadly combination of ignorance and arrogance), and he is writing about something that genuinely alarms him. Some people may be public-spirited enough to give up their last few weeks or months of life for the benefit of strangers, but such a choice should be fully theirs. It should not be forced, pressured, manipulated or "protocoled." Carol Gabriel Dover, N.H. Science Times welcomes letters from readers. Those submitted for publication must include the writer's name, address and telephone number. E-mail should be sent to scitimes@nytimes.com. Send letters to Science Editor, The New York Times, 620 Eighth Avenue, New York, N.Y. 10018.