Although there is a significant number of books and essays in which Aquinas's thought is examined in some detail, there are still many aspects of his writings that remain unknown to those outside the field of Thomistic studies; or which are generally misunderstood. An example is Aquinas's account of the origins of individual human life. This is the subject of a chapter in a recent book by Robert Pasnau on Thomas Aquinas on Human Nature (Cambridge: CUP, 2001). Since there will (...) be readers whose only knowledge of the issues in question will come from Pasnau's account, and since that account is contentious in substance, and advanced in advocacy of a particular moral interest, it is necessary to provide another, and, we believe, more credible account of the issue of when human life begins, as this may be determined on the basis of known empirical facts and Aquinas's metaphysics, and a more accurate representation of how (and how extensively) this matter has been treated hitherto. The morality of abortion turns on two important sets of issues: the first metaphysical, concerning the beginnings of human life and the specific status of the embryo; the second, ethical, having to do with the nature and scope of value and associated moral requirements. Besides engaging in exegesis we address both issues in philosophical terms. (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)

One strategy for arguing that it should be legally permissible to create human embryos, or to use of 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 law. 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. (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)

I investigate Thomas Aquinas's metaphysical account of human death, which is defined in terms of a rational soul separating from its material body. The question at hand concerns what criterion best determines when this separation occurs. Aquinas argues that a body has a rational soul only insofar as it is properly organised to support the soul's vegetative, sensitive, and rational capacities. According to the ‘higher‐brain’ concept of death, when a body can no longer provide the biological foundation necessary for the (...) operation of conscious rational thought and volition, a substantial change occurs in which the rational soul departs and the body left behind is a ‘humanoid animal’ or a mere ‘vegetable.’I argue that the separation of soul and body does not occur until the body ceases to function as a unified, integrated organism. A rational soul is not only the seat of a human being's rational capacities; it is also the principle of the body's sensitive and vegetative capacities. Since Aquinas defines a human being as a composite of soul and body, and not with merely the exercise of rational capacities, the determination of death requires incontrovertible evidence that the body has ceased all the operations that correspond to the soul's proper capacities. The evidence of this is the body's loss of its integrative organic unity and the criterion for determining when this loss occurs is the irreversible cessation of whole‐brain functioning. (shrink)

The scope of embryo research in the UK has been expanded by the Human Fertilisation and Embryology Regulations 2001. Two advisory bodies—the Chief Medical Officer’s Expert Group and the House of Lords’ Select Committee—presented various arguments in favour of embryo research. One of these is the view that, just as lottery tickets have relatively little value before the draw because of the low probability of their being the winning ticket, early embryos have relatively little value because of the presumed low (...) probability that they will mature into more developed embryos. This argument from probability is questioned in this paper, as well as the contention that allowing embryo destruction is incompatible with the view that embryos have full moral status. Although I challenge Savulescu’s view that early embryos should be entered into a lottery in which they are subjected to the probability of being destroyed , a revised version of Thomson’s analogy of the famous violinist defies the view that the position that the embryo has full moral status is incompatible with qualified support for embryo destruction. (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)

‘When did I, a human person, begin to exist?’ In developing an answer to this question, I utilize a Thomistic framework, which holds that the human person is a composite of a biological organism and an intellective soul. Eric Olson and Norman Ford both argue that the beginning of an individual human biological organism occurs at the moment when implantation of the zygote in the uterus occurs and the ‘primitive streak’ begins to form. Prior to this point, there does not (...) exist an individual human organism, but a cluster of biological cells which has the potential to split and develop as one or more separate human organisms (identical twinning). Ensoulment (the instantiation of a human intellective soul in biological matter) does not occur until the point of implantation. This conception of the beginning of human personhood has moral implications concerning the status of pre‐implantation biological cell clusters. A new understanding of the beginning of human personhood entails a new understanding of the morality of certain medical procedures which have a direct affect on these cell clusters which contain human DNA. Such procedures discussed in this article are embryonic stem cell research, in vitro fertilization, procured abortion, and the use of abortifacient contraceptives. (shrink)