本文探討人類胚胎具有怎樣的形上與道德地位，是許多生命倫理議題共同的基礎問題。文分四部分，首先，先說明問題的背景與重要性，指出本問題無論是對傳統的墮胎課題，或對當今最熱門的胚胎幹細胞研究或人類複製的倫理探討，都是不可規避的問題。其次，本文在討論這個問題之前，將先界定問題的精確意涵。這裡其實有兩個息息相關但卻不太一樣的問題，一個是胚胎形上地位的問題，一個是胚胎道德地位的問題。形上地位的問題要問的是胚胎是否是位格，而道德地位問題則是胚胎是否因而具有位格的尊嚴。由於位格尊嚴仍是相當籠統的觀念，本文將問題聚焦在一個具體的問題上，亦即在正常情境下是否可以為了醫學研究而殺害胚胎？界定好問題意涵後，本文最主要的論述在第三部份。這裡先探討位格是什麼，然後以此為基礎來處理「人類胚胎是否是位格」這個根本問題，最後再輔以「謹慎論證」指出：人類胚胎是位格，或至少，在沒有充分證據顯示它不是位格的情形下，應將之視為位格。第四部分是結論，根據前一部分之討論，若人類胚胎應被當成位格來看待，那麼，在正常情境下，為了促進醫學研究與人類福祉而殺死胚胎是不合乎倫理的。

Exploring the metaphysical and moral status of human embryo, one of the most fundamental questions underlying many significant bioethical issues, this essay is divided into four parts. It is firstly to be shown that not only the traditional moral controversy surrounding abortion but also that of the most cutting-edge researches of embryonic stem cell and human cloning can not be properly dealt with without first addressing the question of the metaphysical and moral status of human embryo. Secondly, the meaning of the question will be precisely defined so that the discussion can be rightly focused. The metaphysical part of the question is concerned with the issue whether human embryo is an entity with personhood, i.e. whether it is at the same time a human person. The second part is accordingly the moral question whether a human embryo has the dignity of a person and therefore shall be treated as an end by itself and not as only a means, which again means whether it is morally wrong to kill human embryos for the sake of the welfare of humankind. The main arguments for and contra the personhood of human embryos are presented in the third part after a comprehensive account of personhood is offered as a basis for the discussion. Different arguments such as speciesism, identity, continuity, potentiality and last but not least, benefit of the doubt-argument are evaluated and appealed to. The thesis arrived at is that human embryos are persons or at least shall be treated as persons when the antithesis is not sufficiently and well grounded. The fourth and last part concludes the essay with the claim that in normal situations it is immoral to kill human embryos for the progress of the medicine and the welfare of the mankind.