But a truly comprehensive bioethics must investigate the meaning of life on at least all three levels. The most important thing about the meaning of life is that we must be humble enough to admit that we probably don't know it. This is because, 1. And even those of us who believe in God must admit that we know nothing of His thoughts. The meaning of life must not be confused with quality of life.
Quality of life is a quantifiable clinical concept.
But it is obvious that one can have a high quality of life with little meaning. Or, conversely, one can have a terribly low quality of life while for the first time reflecting deeply and finding high meaning. As friends in the Eubios family know, I try to draw heavily on Israeli tradition in bioethics. And many people think that sanctity of life is part of Judaism. But really I have never found mention of sanctity of life in any traditional Israeli source - Bible, Mishna, Talmud, Maimonides etc.