Contemporary philosophical discussion on human embryonic stem cell research has focused primarily on the metaphysical and meta-ethical issues suchresearch raises. Though these discussions are interesting, largely ignored are arguments rooted in the secular research ethics tradition already informing humansubject research. This tradition countenances the notion of vulnerability and that vulnerable human subjects (of which human embryos are likely members)ought to be protected from research-related harms. This is the basic idea behind the argument from vulnerability, and it enjoys prima facie plausibility. (...) This articlepresents the vulnerability argument and then focuses critically on several lines of attack including: (1) twinning and totipotency arguments, (2) embryo-rescuearguments, and (3) natural loss arguments. The article concludes that there is no good defeater for the vulnerability argument, and, therefore, we have undefeated reasons for protecting human embryos from research related harms. (shrink)

It is standardly assumed that there are three — and only three — ways to solve problem of temporary intrinsics: (a) embrace presentism, (b) relativize property possession to times, or (c) accept the doctrine of temporal parts. The first two solutions are favoured by endurantists, whereas the third is the perdurantist solution of choice. In this paper, I argue that there is a further type of solution available to endurantists, one that not only avoids the usual costs, but is structurally (...) identical to the temporal-parts solution preferred by perdurantists. In addition to providing a general characterization of this new type of solution, I discuss certain of its anticipations in the literature on bundle theory, as well as provide a detailed development of it in terms of my own preferred metaphysics of ordinary objects — namely, a distinctive form of substratum theory tracing to Aristotle. (shrink)

In this paper I examine the question of when human life begins from a neo-Aristotelian perspective. In my view, the basic principles of Aristotle’s metaphysics inform an account of human life (and the human person) that offers the best available explanation of the available phenomena. This account – the substance account of the human person – can fully incorporate the contemporary findings of empirical embryology, while also recognizing the essential uniqueness of rational human nature.

Absolute identity seems at first sight to be presupposed in the branch of formal logic called identity theory. Classical identity theory may be obtained by adjoining a single schema to ordinary quantification theory.

Contemporary philosophical discussion on human embryonic stem cell research has focused primarily on the metaphysical and meta-ethical issues suchresearch raises. Though these discussions are interesting, largely ignored are arguments rooted in the secular research ethics tradition already informing humansubject research. This tradition countenances the notion of vulnerability and that vulnerable human subjects (of which human embryos are likely members)ought to be protected from research-related harms. This is the basic idea behind the argument from vulnerability, and it enjoys prima facie plausibility. (...) This articlepresents the vulnerability argument and then focuses critically on several lines of attack including: (1) twinning and totipotency arguments, (2) embryo-rescuearguments, and (3) natural loss arguments. The article concludes that there is no good defeater for the vulnerability argument, and, therefore, we have undefeated reasons for protecting human embryos from research related harms. (shrink)

When does a human being begin to exist? We argue that it is possible, through a combination of biological fact and philosophical analysis, to provide a definitive answer to this question. We lay down a set of conditions for being a human being, and we determine when, in the course of normal fetal development, these conditions are first satisfied. Issues dealt with along the way include: modes of substance-formation, twinning, the nature of the intra-uterine environment, and the nature of the (...) relation between fetus and mother (connection, parthood, dependence). (shrink)

The mainstream rationale for equating brain death (BD) with death is that the brain confers integrative unity upon the body, transforming it from a mere collection of organs and tissues to an organism as a whole. In support of this conclusion, the impressive list of the brains myriad integrative functions is often cited. Upon closer examination, and after operational definition of terms, however, one discovers that most integrative functions of the brain are actually not somatically integrating, and, conversely, most integrative (...) functions of the body are not brain-mediated. With respect to organism-level vitality, the brains role is more modulatory than constitutive, enhancing the quality and survival potential of a presupposedly living organism. Integrative unity of a complex organism is an inherently nonlocalizable, holistic feature involving the mutual interaction among all the parts, not a top-down coordination imposed by one part upon a passive multiplicity of other parts. Loss of somatic integrative unity is not a physiologically tenable rationale for equating BD with death of the organism as a whole. (shrink)

ABSTRACT In a paper published in Bioethics, Jason Eberl has argued that early embryos are not persons and should not be granted the status possessed by them.1 Eberl bases this position upon the following claims: (1) The early embryo has a passive potentiality for development into a person. (2) The early embryo has not established both ‘unique genetic identity’ and ‘ongoing ontological identity’, which are necessary conditions for ensoulment. (3) The early embryo has a low probability of developing into a (...) more developed embryo. This paper examines these claims. I argue against (1) that a plausible view is that the early embryo has an active potentiality to grow into a more developed embryo. Against (2), I argue that neither ‘unique genetic identity’ nor ‘ongoing ontological identity’ are necessary conditions for ensoulment, and that ‘ongoing ontological identity’ is established between early embryos and more developed embryos. Against (3), I argue that the fact that the early embryo has a low probability of developing into a more developed embryo, if true, does not warrant the conclusion that the early embryo is not a person. If Eberl is right that the human soul is that which organises the activities of a human being and that ensouled humans are persons, embryos are persons from conception. (shrink)

When does a human being begin to exist? Barry Smith and Berit Brogaard have argued that it is possible, through a combination of biological fact and philosophical analysis, to provide a definitive answer to this question. In their view, a human individual begins to exist at gastrulation, i. e. at about sixteen days after fertilization. In this paper we argue that even granting Smith and Brogaard's ontological commitments and biological assumptions, the existence of a human being can be shown to (...) begin much earlier, viz., with fertilization. Their interpretative claim that a zygote divides immediately into two substances and therefore ceases to exist is highly implausible by their own standards, and their factual claim that there is no communication between the blastomeres has to be abandoned in light of recent embryological research. (shrink)

According to the Constitution View of persons, a human person is wholly constituted by (but not identical to) a human organism. This view does justice both to our similarities to other animals and to our uniqueness. As a proponent of the Constitution View, I defend the thesis that the coming-into-existence of a human person is not simply a matter of the coming-into-existence of an organism, even if that organism ultimately comes to constitute a person. Marshalling some support from developmental psychology, (...) I give a broadly materialistic account of the coming-into-existence of a human person. I argue for the metaphysical superiority of the Constitution View to Biological Animalism, Thomistic Animalism, and other forms of Substance Dualism. I conclude by discussing the single implication of the Constitution View for thinking about abortion. Footnotesa Thanks to Gareth Matthews and Catherine E. Rudder for comments. I am also grateful to other contributors to this volume, especially Robert A. Wilson, Marya Schechtman, David Oderberg, Stephen Braude, and John Finnis. (shrink)

The majority of philosophers believe that the existence of spatially coincident entities is not only a coherent idea but that there are millions of such entities. What such philosophers do not countenance are spatially coincident entities of the same kind. We will call this ‘Locke's Thesis’ since the denial goes back to An Essay Concerning Human Understanding. It is there that Locke wrote, ‘For we never finding, nor conceiving it possible that two things of the same kind should exist in (...) the same place at the same time, we rightly conclude that, whatever exists anywhere at any time, excludes all of the same kind, and is there itself alone.’ It is not clear to me that the believer in spatially coincident entities can draw the ‘ontological line’ where Locke does. Many of the reasons that lead Locke and others to maintain that there exist spatially coincident entities of different kinds would also suggest that there are spatially coincident entities of the same kind. To illustrate this claim, a scenario of spatially coincident roads will be presented. (shrink)

abstract This paper re‐examines some well‐known and commonly accepted arguments for the non‐individuality of the embryo, due mainly to the work of John Harris. The first concerns the alleged non‐differentiation of the embryoblast from the trophoblast. The second concerns monozygotic twinning and the relevance of the primitive streak. The third concerns the totipotency of the cells of the early embryo. I argue that on a proper analysis of both the empirical facts of embryological development, and the metaphysical importance or otherwise (...) of those facts, all three arguments are found wanting. None of them establishes that the embryo is not an individual human being from the moment of conception. (shrink)

It seems that at conception something is formed which, due to its genetic make-up, has the potentiality to develop into a full-blown human being. Many believe that in virtue of this potentiality, this organism, the human zygote or early embryo, has an intrinsic value which makes it wrong to use or produce it merely as a means to some end, e.g., some scientific end such as to produce embryonic stem cells. Against this it is here argued, first, that it does (...) not follow from the fact that something has a potential to become a human being that it already is a human being. In fact, a human being begins to exist no earlier than a couple of weeks after conception, at the stage known as gastrulation. Thus, even granted the questionable assumption that something has intrinsic value in virtue of being a human being, the zygote will not have intrinsic value. Secondly, the value an embryo has in virtue of its potentiality to become a full-blown human being can only be instrumental, a value as a means. But Of course it cannot be wrong to treat that which has merely instrumental value as a mere means or instrument to some end. (shrink)

In this paper, I present an Aristotelian solution to the problem of material constitution. The problem of material constitution arises whenever it appears that an object a and an object b share all of the same parts and yet are essentially related to their parts in different ways. (A familiar example: A lump of bronze constitutes a statue of Athena. The lump and the statue share all of the same parts, but it appears that the lump can, whereas the statue (...) cannot, survive radical rearrangements of those parts.) I argue that if we are prepared to follow Aristotle in making a distinction between numerical sameness and identity, we can solve the problem of material constitution without recourse to co-location or contingent identity and without repudiating any of the familiar objects of common sense (such as lumps and statues) or denying that these objects have the essential properties we ordinarily think that they have. (shrink)

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.

This paper defends the permissibility of stem cell research against a theological objector who objects to it by appealing to "souls.".

A number of philosophers maintain that the destruction of an embryo in the first 2 weeks after fertilization is not morally problematic as it is metaphysically impossible for any human organism to then have existed. We contend that the typical adult human organism was once a zygote so there is no metaphysical shortcut to justify early abortion. We show that five arguments against human organisms ever having been zygotes fail. All of the arguments have to do with one variant or (...) another of the zygote or early embryo dividing. They do not provide any reason to believe that since some adult organisms are not identical to zygotes due to earlier divisions, none could have been. (shrink)

It has been argued that the possibility of monozygotic twinning disproves the conservative position on foetal personhood that defines the foetus as a person from conception. This article will canvass arguments for and against this proposition, in order to arrive at a conclusion as to the relative strength of this finding.

Some philosophers argue that, because it is subject to twinning and fusion, the early human embryo cannot hold strong moral standing. Supposedly, the fact that an early human embryo can twin or fuse with another embryo entails that it is not a distinct individual, thus precluding it from holding any level of moral standing. I argue that appeals to twinning and fusion fail to show that the early human embryo is not a distinct individual and that these appeals do not (...) provide us with plausible reasons for denying the strong moral standing of the early human embryo. I recognize one possible exception to this general assessment, a particular version of the appeal to fusion. Embryo fusion that results in tetragametic chimerism provides some reason for doubting the early human embryo's moral standing. But twinning and fusion are otherwise irrelevant in this context. (shrink)

Hud Hudson presents an innovative view of the metaphysics of human persons according to which human persons are material objects but not human organisms. In developing his account, he formulates and defends a unique collection of positions on parthood, persistence, vagueness, composition, identity, and various puzzles of material constitution. The author also applies his materialist metaphysics to issues in ethics and in the philosophy of religion. He examines the implications for ethics of his metaphysical views for standard arguments addressing the (...) moral permissibility of our treatment of human persons and their parts, fetuses and infants, the irreversibly comatose, and corpses. He argues that his metaphysics provides the best foundation in the philosophy of religion for the Christian doctrine of the resurrection of the body. Hudson addresses a broad range of metaphysical issues, but among his most strikingly original contributions are his defense of the "Partist" view and his argument for the compatibility of Christianity with a materialistic theory of human persons. (shrink)

An argument against the bias towards the near; how a defence of temporal neutrality is not a defence of S; an appeal to inconsistency; why we should reject S and accept CP.

The question whether two things can be in the same place at the same time is an ambiguous one. At least three distinct questions could be meant: Can two things simpliciter be in the same place at the same time? Can two things of the same kind be in the same place at the same time? Can two substances of the same kind be in the same place at the same time? The answers to these questions vary. In what follows, (...) all three will be discussed in the light both of recent and of classic earlier examinations of the matter. The following theses will be defended. (shrink)

In this essay, I attempt to provide answers to the following four queries concerning the metaphysics of early human embryogenesis. (1) Following its first cellular fission, is it coherent to claim that one and only one of two “blastomeric” twins of a human zygote is identical with that zygote? (2) Following the fusion of two human pre-embryos, is it coherent to claim that one and only one pre-fusion pre-embryo is identical with that postfusion pre-embryo? (3) Does a live human being (...) come into existence only when its brain comes into existence? (4) At implantation, does a pre-embryo become a mere part of its mother? I argue that either if things have quidditative properties or if criterialism is false, then queries (1) and (2) can be answered in the affirmative; that in light of recent developments in theories of human death and in light of a more “functional” theory of brains, query (3) can be answered in the negative; and that plausible mereological principles require a negative answer to query (4). (shrink)

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.

The author reviews one of the more intriguing articles in the stem cell research issue of the journal Metaphilosophy (April 2007), “Killing Embryos for Stem Cell Research,” by Jeff McMahan. He begins by recapitulating McMahan’s argument against the proposition that we are essentially individual human organisms. He then turns to two main critiques of the argument. First, he shows that the term “essentially” is insufficiently defined by McMahan and, more important, if we take the typical explication of the concept by (...) modal metaphysicians, then the claim “we are essentially human beings” is true—contrary to McMahan’s argument. Second, the author offers a counterexample to McMahan’s implicit acceptance of the principle that only beings who have developed the capacity for self-consciousness are the proper subjects of moral worth. The author presents a regenerative therapy example to show that McMahan’s commitment on this point is counterintuitive. National Catholic Bioethics Quarterly 8.2 (Summer 2008): 255–264. (shrink)

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 involed in twinning and the property of early embryos to be divisible, 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. (shrink)

When a human being comes into existence is crucial in bioethics. Conceptionism is the view that a human being comes into existence at conception. The twinning argument is an influential objection to this view. All versions of the twinning argument rely on a metaphysics of material objects, namely, endurantism. Given this, a strategy for defending conceptionism against the twinning argument is to deny endurantism and adopt an alternative metaphysics of material objects. A version of this strategy which has been debated (...) in this journal is to adopt perdurantism, or the ‘multiple occupancy view’, on which monozygotic twins share the zygote region as a temporal part. We present a novel version of this strategy: conceptionists can evade the twinning argument by adopting an exdurantist metaphysics of material objects. We suggest reasons for thinking that this is a plausible and, indeed, preferable way for conceptionists to avoid the twinning argument. (shrink)

In explicating his version of the Organism View, Eric Olson argues that you begin to exist only after twinning is no longer possible and that you cannot survive a process of inorganic replacement. Assuming the correctness of the Organism View, but pace Olson, I argue in this paper that the Organism View does not require that you believe either proposition. The claim I shall make about twinning helps to advance a debate that currently divides defenders of the Organism View, while (...) the claim I shall make about inorganic replacement will help to put the Organism View on a par with its rival views by allowing it to accommodate a plausible intuition that its rivals can accommodate, namely, the intuition that you can survive a process of inorganic replacement. Both claims, I shall also argue, are important for those who are interested in the identity condition of a human organism, even if they do not hold the view that you are essentially an organism. (shrink)

This paper re-examines the question of whether quirks of early human foetal development tell against the view (conceptionism) that we are human beings at conception. A zygote is capable of splitting to give rise to identical twins. Since the zygote cannot be identical with either human being it will become, it cannot already be a human being. Parallel concerns can be raised about chimeras in which two embryos fuse. I argue first that there are just two ways of dealing with (...) cases of fission and fusion and both seem to be available to the conceptionist. One is the Replacement View according to which objects cease to exist when they fission or fuse. The other is the Multiple Occupancy View – both twins may be present already in the zygote and both persist in a chimera. So, is the conceptionist position tenable after all? I argue that it is not. A zygote gives rise not only to a human being but also to a placenta – it cannot already be both a human being and a placenta. Neither approach to fission and fusion can help the conceptionist with this problem. But worse is in store. Both fission and fusion can occur before and after the development of the inner cell mass of the blastocyst – the entity which becomes the embryo proper. The idea that we become human beings with the arrival of the inner cell mass leads to bizarre results however we choose to accommodate fission and fusion. (shrink)

During the first 16 days after fertilization, the developing embryo has the capacity to separate into two genetically identical embryos, or monozygotic twins (triplets, etc.). Because of this capacity, philosophers typically argue that the pre-16 day embryo is not a human being. On a Biological Account of Personal Identity (BAPI), which considers us human beings as essentially organisms, the development of the embryo into an organism at 16 (or 21) days marks our origins. The development of an embryo into an (...) organism is also said to mark the point at which the embryo loses its potential to give rise to monozygotic twins. This is considered a strength of the Biological account of our origins. I will argue here that it is the BAPI's own criteria that will have to allow cases of monozygotic twinning occurring even after 16 days, and that in virtue of this a Biological Account faces twinning puzzles usually reserved for earlier accounts of our origins. (shrink)

The view that human beings begin to exist at fertilization (namely conceptionism) faces a serious challenge from the twinning argument, that identical twins coming from the same zygote must be numerically distinct from the zygote and so did not exist at fertilization. Recently, some philosophers have claimed that the twinning argument rests on a particular metaphysical theory of persistence, namely endurantism, on which a human being, for example, is wholly present at every moment of her existence. And we can easily (...) refute the argument, they claim, by employing perdurantism or exdurantism, according to which a human being is a temporally extended entity with temporal parts or a momentarily existing stage who has other momentarily existing stages as counterparts. I argue that such claims are mistaken. The twinning argument does not rest on endurantism and can be formulated in terms of perdurantism to provide a good reason for perdurantists to reject conceptionism. And exdurantism does not have any advantage in defending conceptionism either, for it already concedes more than what the twinning argument aims to show. (shrink)

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. (shrink)

ABSTRACT Summed up in the coinage of the term ‘pre‐embryo’is the denial that human beings, as such, begin to exist from the moment of conception. This denial, which may be thought to have significant moral implications, rests on two kinds of reason. The first is that the pre‐embryo lacks the characteristics of a human being. The second is that the pre‐embryo lacks what it takes to be an individual human being. The first reason, I argue, embodies an untenable view of (...) what it is to be human. The second reason exploits certain logical difficulties which arise over the possibility of twinning. I question the relevance of the appeal to such difficulties and conclude that there is no good reason for denying that a human being begins to exist from the moment of conception. (shrink)

This paper presents an account of how human spontaneous embryonic chimeras are formed. On the prevalent view in the philosophical literature, it is said that chimeras are the product of two embryos that fuse to form a new third embryo. We call this version of fusion synthesis. In contrast to synthesis, we present an alternative mechanism for chimera formation called incorporation, wherein one embryo incorporates the cells of a second embryo into its body. We argue that the incorporation thesis explains (...) other types of chimera formation, which are better understood, and is more consistent than synthesis with what is known about embryological development. Incorporation also has different implications than synthesis and so avoids the philosophical puzzles that are often said to accompany embryonic chimera formation—puzzles which pose problems to the human embryo’s persistence from fertilization to the fetal stage of human development. (shrink)

I consider the argument, thought to clinch the moral case for use of a human embryo solely as a means, that only a human individual can be a person, because it can happen at any time before formation of the primitive streak that an embryo splits into monozygotic twins, no embryo in which the primitive streak has not formed is a human individual, and therefore no embryo in which the primitive streak has not formed is a person. I explore the (...) following proffered arguments for : indivisibility is a necessary condition of individuality, nonidentity of an embryo with successor twins impugns the embryo’s individuality, and totipotency of an embryo’s constituents is inconsistent with the embryo’s being a human individual. These arguments are tested and found wanting; so too is an alternative to , the argument that indivisibility is intrinsic to personhood. Whereupon is unsustained. In search of ways to rehabilitate the nonindividuation argument, I canvass alternative metaphysical views and inquire further into biological individuality, but find that the argument cannot be saved. I conclude by analyzing where this leaves matters concerning the morality of embryo use. (shrink)

I consider the argument, thought to clinch the moral case for use of a human embryo solely as a means, that only a human individual can be a person, because it can happen at any time before formation of the primitive streak that an embryo splits into monozygotic twins, no embryo in which the primitive streak has not formed is a human individual, and therefore no embryo in which the primitive streak has not formed is a person. I explore the (...) following proffered arguments for : indivisibility is a necessary condition of individuality, nonidentity of an embryo with successor twins impugns the embryo’s individuality, and totipotency of an embryo’s constituents is inconsistent with the embryo’s being a human individual. These arguments are tested and found wanting; so too is an alternative to, the argument that indivisibility is intrinsic to personhood. Whereupon is unsustained. In search of ways to rehabilitate the nonindividuation argument, I canvass alternative metaphysical views and inquire further into biological individuality, but find that the argument cannot be saved. I conclude by analyzing where this leaves matters concerning the morality of embryo use. (shrink)

Response to Jan Deckers' critique of the author's earlier article on the beginning of personhood from a Thomistic perspective in which the author revises and further refines his view.