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In this paper I defend the view that a zygote is a human from the fission objection that is widely thought to be decisive against the view. I do so, drawing upon a recent discussion of this issue by John Burgess, by explaining in detail the metaphysical position the proponent of the view should adopt in order to rebut the objection., (© 2010 Blackwell Publishing Ltd.)

This essay has two purposes. The first is to argue that our moral duties towards human embryos should be assessed in light of the Golden Rule by asking the normative question, "how would I want to be treated if I were an embryo?" Some reject the proposition "I was an embryo" on the basis that embryos should not be recognized as persons. This essay replies to five common arguments denying the personhood of human embryos: (1) that early human embryos lack ontological individuation; (2) that they are members of the species Homo sapiens but not yet human persons; (3) that the argument for personhood commits the "heap argument" fallacy; (4) that since human procreation in nature is inefficient, human embryos cannot be persons; and (5) the "burning building" scenario proves that all arguments for personhood are irrational or inconsistent. The second purpose is to set forth and criticize in light of the normative judgement defended in part one the present legal situation of cryo-preserved embryos in the U.S. The essay ends by proposing legislative reforms to protect ex utero human embryos.

Catholic opponents of abortion and embryonic stem cell research usually base their position on a hylomorphic account of ensoulment at fertilization. They maintain that we each started out as one-cell ensouled organisms. Critics of this position argue that it is plagued by a number of intractable problems due to fission (twinning) and fusion. We're unconvinced that such objections to early ensoulment provide any reason to doubt the coherence of the hylomorphic account. However, we do maintain that a defense of ensoulment at fertilization must deny that we're essentially organisms.

In this essay, I defend three Simple Views concerning human beings. First, that the human embryo is, from the one-cell stage onwards, a single unitary organism. Second, that when an embryo twins, it ceases to exist and two new embryos come into existence. And third, that you and I are essentially human organisms. This cluster of views shows that it is not necessary to rely on co-location, or other obscure claims, in understanding human embryogenesis.

From fertilization to approximately the sixteenth day of development, human embryonic cells are said to have the capacities of totipotency and monozygotic twinning, both of which are problematic to a theory of ensoulment at fertilization. In this article I will address the problems which these capacities pose to such a theory and present an interpretation of the biological data which renders ensoulment at fertilization more plausible. I will then argue that not only is an ensoulment theory consistent with current biological data on the human embryo, but it may offer an explanation for the phenomencon of monozygotic twinning.

Norman Ford and other scholars argue that the human embryo cannot have a human soul until after week two of fertilization. They claim that the individuality proper to ensoulment requires the development of the primitive streak and excludes the possibility of twinning. Their arguments are refuted by principles of philosophical realism inspired by Aristotle and Aquinas. According to these principles, the new substance formed by the union of the paternal and maternal DNA has a rational soul. The zygote, to be human, requires a human soul that determines its human development. The primitive streak is part of this development, not a condition of it. Twinning does not disprove the existence of a previous embryo with a human soul. Instead it indicates the existence of a new embryo derived from some totipotent cells that separate from the first embryo.

The purpose of this essay is to offer support for the substance view of persons, the philosophical anthropology defended by Patrick Lee in his essay. In order to accomplish this the author (1) presents a brief definition of the substance view; (2) argues that the substance view has more explanatory power in accounting for why we believe that human persons are intrinsically valuable even when they are not functioning as such (e.g., when on is temporarily comatose), why human persons remain identical to themselves over time, and why it follows from these points that the unborn are human persons; and (3) responds to two arguments that attempt to establish the claim that the early human being is not a unified substance until at least fourteen days after conception.

In this chapter, I review some of the background thinking concerning matters of moral status that I had developed in previous years and that I would now bring to the work of the Human Embryo Research Panel. Two ideas were at the forefront of my thinking. First, that biology usually offers not decisive "events" but only continuous processes of development. Second, in making status determinations we do not so much "identify" a point on a developmental continuum where moral respect should be accorded as "choose" that point. These choices are "balancing decisions" in which the community of moral agents weighs its interests in protecting an entity against the burdens of doing so. After illustrating these two contentions, I consider some of the reasons why thinkers on the "right" and "left" of our bioethics debates have resisted or missed this basic insight.

The phenomenon of twinning in early fetal development has become a popular source for doubt regarding the ascription of moral status to early embryos. In this paper, the possible moral basis for such a line of reasoning is critically analysed with sceptical results. Three different versions of the argument from twinning are considered, all of which are found to rest on confusions between the actual division of embryos involved in twinning and the property of early embryos to be divisible, to be based on highly questionable ethical assumptions, or to imply inconsistent claims regarding the moral importance of potentiality and/or the moral status of embryos. This is taken to expose a number of related inconsistencies in the moral basis of pro-life positions. In particular, ascribing moral significance to the property of being (in)divisible is found to be incompatible with the claim that human individuals possess unique values which could underpin an absolute moral ban on murder.

One strategy for arguing that it should be legally permissible to create human embryos, or to use spare human embryos, for scientific research purposes involves the claim that such embryos cannot be persons because they are not human individuals while twinning may yet take place. Being a human individual is considered to be by most people a necessary condition for being a human person. I argue first that such an argument against the personhood of embryos must be rationally conclusive if their destruction in public places such as laboratories is to be countenanced. I base this argument on a popular understanding of the role that the notion of privacy plays in abortion laws. I then argue that such arguments against personhood are not rationally conclusive. The claim that the early embryos is not a human individual is not nearly as obvious as some assert.

One potentially valuable use of cloning is to provide a source of tissues or organs for transplantation. The most important objection to this use of cloning is that a human clone would be the sort of entity that it would be seriously wrong to kill. I argue that entities of the sort that you and I essentially are do not begin to exist until around the seventh month of fetal gestation. Therefore to kill a clone prior to that would not be to kill someone like you or me but would be only to prevent one of us from existing. And even after one of us begins to exist, the objections to killing it remain comparatively weak until its psychological capacities reach a certain level of maturation. These claims support the permissibility of killing a clone during the early stages of its development in order to use its organs for transplantation.

Three basic political positions on embryo research will be identified as libertarian, conservative, and social-democratic. The Human Embryo Research Panel will be regarded as an expression of the social-democratic position. A taxonomy of the ethical issues addressed by the Panel will then be developed at the juncture of political and ethical modes of reflection. Among the arguments considered will be those for the separability of the abortion and embryo research debates; arguments against the possibility of the preembryo being a person, especially arguments associated with totipotency and the significance of the primitive streak; and the various reasons for regulating embryo research, including those associated with respect for the preembryo, the protection of traditional views of human procreation, and the prevention of commercialization.

The argument that human life should be fully protected once conception is complete has been challenged by the claim that at that time such life is not genuinely individuated in the morally required sense. This essay analyzes the "conception versus individuation" exchange and directs attention to the communal contexts within which the relevant arguments and counter-arguments arise.

Howsepian has presented a number of thought experiments, which are designed to undermine my claim that our identity through time is grounded in the continued existence of those structures in our brains which directly underlie mental functioning. I argue that the conclusions which Howsepian draws from these thought experiments are mistaken, and that his discussion of them is vitiated, in particular, by his failure to distinguish between personal identity and the identity of the associated human organism.

Michael Lockwood has recently concluded that it can be morally permissible to perform potentially damaging non-therapeutic experiments on live human (pre)embryos. The reasons he provides in support of this conclusion commit him inter alia to the following controversial theses: (i) an organism's potential for twinning bears critically on the identity conditions for that organism; and (ii) functionally intact mentality-mediating neurological structures play a critical role in establishing the identity conditions for human organisms. I argue that Lockwood has given us no good reason to endorse either of these theses and, hence, that he has given us no good reason to believe that it can be morally permissible to perform potentially damaging non-therapeutic experiments on live human (pre)embryos.

In his recent book Crossing the Threshold of Hope, Pope John Paul II airs his views on human reproduction. The pity is that he ignores most of modern genetics and embryology.

The thesis that the human zygote is essentially identical with the person into which it can develop is difficult to maintain, because the zygote can become several persons. In addition, the thesis depends upon ambiguities in the notions of human being, human individual, human body, and soul. A human being may be individual in the sense of either a biologically integrated unity or a psychologically integrated unity. A person is a psychologically integrated unity, because it must unify its experiences in morally imputable actions. To say that the zygote is a person requires one to assert that the zygote has the same principle of psychological integration, i.e., a rational soul, as one who can obviously manifest psychological integration. The assertion is incapable of being justified in empirical (e.g., non-religious) terms.

The link between gynaecology and ethics, one time neglected, turns out to be inevitable. The gynaecologist's work has to be oriented to the highest value on the earth, i.e., to the human person, considered in both its developmental and social dimensions. The task of a doctor (physician) is to further the health of the human person, and the specific task of the gynaecologist and obstetrician is to help professionally in the transmission of human life. To fulfill this task, they have to know the correct answer to the question when human life begins, the answer given by embryology and medical thermodynamics. The human embryo has to be considered and treated as a human person. This includes the exclusion of such acts as direct or indirect abortion, experimental use of embryos, and all kinds of genetic manipulation. The right ways of human fertilization are a consequence of the dignity of the child and of the married couple, as well as of their right to love and to be loved. It excludes the insemination, the homogeneous and heterogeneous fertilization in vitro, and the surrogate motherhood. The gynaecologists, obstetricians and midwives have to refuse to perform the nocive or immoral interventions. They should be ready to do their best in helping people in the right transmission of human life.