But there is some possibility, certainly, that this could happen in the near future, when this will be technologically feasible. With the progress of medicine and biotechnology, many new and complicated issues of bioethics will present themselves. I think that one approach to this problem is to make a distinction between parts of the body that may be replaced and those that may not. Human hair is used, for example, in thermometers. Hair is undeniably a part of the human body, but since it grows back its use is universally regarded as acceptable.
Blood is also replaceable.
There will be no influence on a person's individuality or character even if all of his blood is replaced in transfusion. To a certain extent, skin a d organs are also replaceable, and in fact today they are being transplanted from one person to another. If we pursue this line of reasoning, we finally come to the brain, which controls the spiritual, mental activity that is at the core of human personality. The brain does not function in terminal coma patients. They have no will, no thoughts, no feelings.