Okay, I'll bite.
I think it is ethically acceptable to decline or avoid extraordinary means of sustaining life (feeding tubes, respirators, etc.) when it is clear that (1) absent such extraordinary means, nature would take its course and death would occur, and (2) there is no question that the patient would not want such extraordinary means taken. (Which is why DNRs are important. Yes, I need one; thanks for the reminder.
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I do not think it is ethically acceptible to take positive action to end a life. I would be opposed to physician assisted suicide/euthanasia.