In a previous thread, someone made the claim that a fetus is not alive because it depends on it's mother to survive, even if it is at a stage of development that would allow it to survive outside the womb. Now, my question is this. If an adult was on life support, are they alive? I mean, they are dependent on machines to survive. By your own argument, they are not a person, so it's OK to kill them. Do you see how silly your argument is now?