With the advancement of bio-science and bio-technology come nasty new bioethical dilemmas, and some bioethicists have resorted to metaphysics, in particular, the notion of personal identity, to resolve them. I claim, however, that metaphysical accounts of personal identity at present are incapable of withstanding the impact of bioethical dilemmas. Bioethical issues such as criteria of death, brain transplantation, and dementia with/without advance directives invite us to deconstruct three shaky metaphysical notions concerning personal identity so that we can tackle ethical problems (...) more freely and properly. Furthermore, policy makers are advised to be more concerned with a norm or contract that guarantees the long-term welfare of a society of individuals rather than with the pinning down of the identity of a person at the margin of life. In this way, the public can be relieved of a guilt that has been unduly haunting them — when their loved ones were in many ways gone already. (shrink)