In dicephalus conjoined twinning, it appears that two heads share a body; in cephalopagus, it appears that two bodies share a head. How many human animals are present in these cases? One answer is that there are two in both cases—conjoined twins are precisely that, conjoined twins. Another is that the number of humans corresponds to the number of bodies—so there is one in dicephalus and two in cephalopagus. I show that both of these answers (...) are incorrect. Prominent accounts of biological individuation, which treat the organism as an integrated whole, reveal that in these and other cases of conjoined twinning the ‘twins’ share a single human animal. This has a number of consequences for the debate about what we are. First, if animalism is true, individuals of our kind can be—and are—profoundly psychologically divided. Second, cephalopagus twinning does not divide animalism from its rivals, as has been claimed. Finally, animalists can reply to a vicious species of the ‘too many thinkers’ problem to which they are allegedly uniquely vulnerable. (shrink)

We examine the philosophical and ethical issues associated with conjoined twins and their surgical separation. In cases in which there is an extensive sharing of organs, but nevertheless two distinguishable functioning brains, there are a number of philosophical and ethical challenges. This is because such conjoined twins: 1. give rise to puzzles concerning our identity, about whether we are identical to something psychological or biological;2. force us to decide whether what matters from an ethical point of (...) view is the biological life of our organisms or the existence of our consciousness or mind; 3. raise questions concerning when, if ever, it is morally acceptable to sacrifice one of us to save another;4. force us to reflect on the conditions for ownership of organs and the justification of removal of organs for transplantation which causes the death of the donor; 5. raise questions about who should take decisions about life-risking treatments when this cannot be decided by patients themselves.We examine and suggest answers to these questions. (shrink)

Wollen (2022) is a critique of deontological libertarianism, the version of this philosophy predicated upon private property rights and the non-aggression principle. The launching pad for this article of his is the difficulty faced by conjoined twins, who diverge sharply in their view of their desirable future. The present rejoinder maintains that this author’s critique fails; further, that it really has little or nothing to do with conjoined twins per se, but, rather, aims at an entirely (...) different challenge, that of the tie or the dead heat. This latter is a critique that all political economic philosophies face, without exception, and libertarianism does no worse on this challenge than any other, the critique of Wollen to the contrary notwithstanding. (shrink)

In this article I consider the case of the surgical separation of conjoined twins resulting in the immediate and predictable death of the weaker one. The case was submitted to English law by the hospital, and the operation permitted against the parents’ wishes. I consider the relationship between the legal decision and the moral reasons adduced in its support, reasons gaining their force against the framework of much mainstream normative ethical theory. I argue that in a few morally (...) dilemmatic situations, such a legalistic–theoretical approach cannot plausibly accommodate certain irreducible and ineliminable features of the ethical experience of any concrete individual implicated in the situation, and that this failure partly undermines its self–appointed role of guiding such an individual's conduct. For example, the problem as experienced by the judge and by the parents might not be the same problem at all, and some of their respective reasons may be mutually unintelligible or impotent. I certainly do not argue for a rejection of law or of moral theory; I merely challenge their implicit claim to comprehensiveness and their fixation with an idealised and putatively universal rationality modelled on converging scientific enquiry. Finally, I claim that at least in the twins’ case there may be insufficient normative robustness to the conclusions reached, or indeed reachable, by the court in a situation where intuitions and moral reasons pull in fundamentally incommensurable directions; as such, there may be room for an acknowledgement of the spiritual, through a humble abstention from making a decision – which is not to be confused with deciding to do nothing. (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)

: This article draws upon the Roman Catholic distinction between "ordinary" and "extraordinary" means of medical treatment to analyze the case of "Jodie" and "Mary," the Maltese conjoined twins whose surgical separation was ordered by the English courts over the objection of their Roman Catholic parents and Cormac Murphy-O'Connor, the Roman Catholic Cardinal Archbishop of Westminster. It attempts to shed light on the use of that distinction by surrogate decision makers with respect to incompetent patients. In addition, it (...) critically analyzes various components of the distinction by comparing the reasoning used by Catholic moralists in this case with the reasoning used in other cases that raise similar issues, including women facing crisis pregnancies who prefer abortion to adoption and the Indiana "Baby Doe" case. (shrink)

Conjoined twinning is said to show that the number of human people—the number of us—can differ from the number of human organisms, and hence that we are not organisms. The paper shows that these arguments either assume the point at issue, rely on dubious and undefended assumptions, or add nothing to more familiar arguments for the same conclusion.

Various cases of conjoined twinning have been presented as problems for the animalist view that we are animals. In some actual and possible cases of human dicephalus that have been discussed in the literature, it is arguable that there are two persons but only one human animal. It is also tempting to believe that there are two persons and one animal in possible instances of craniopagus parasiticus that have been described. Here it is argued that the animalist can admit (...) that these are cases in which human persons are not animals, without forfeiting the title “animalist.” It is also shown that this is not only an option but also a well-motivated and plausible option for the animalist. Seeing this requires getting clear on what the word “we” should be thought to include in the animalist's claim that we are animals. Here animalism is defended against twinning objections by figuring out how to view the scope of the animalist's identity claim. (shrink)

This paper presents a new challenge for libertarianism. The problem, in a nutshell, is that libertarianism appears to self-destruct in cases where conjoined twins—who share body parts—disagree over what to do with them. The problem is explored, and some solutions are proposed. The verdict is that accepting any of them will make libertarianism harder to defend.

We attempt to shed light on property rights by examining the case of conjoined twins. We do so since their situation is perhaps among the most challenging of all cases of separating “mine” from “thine.”.

I argue that the separation of conjoined twins in infancy or early childhood is unethical. Cases may be divided into three types: both twins suffer from lethal abnormalities, only one twin has a lethal abnormality, or neither twin does. In the first kind of case, there is no reason to separate, since both twins will die regardless of treatment. In the third kind of case, I argue that separation at an early age is unethical because the (...) twins are likely to achieve an irreplaceably good quality of life—the goods of conjoinment—that separation takes away. Evaluation of this possibility requires maturation past early childhood. Regarding the second type, I point out that with conceivable but unrecorded exceptions, these cases will consistently involve sacrifice separation. I present an argument that sacrifice separation is unethical, but in some cases a moral dilemma may exist in which separation and refraining from separation are both unethical. Perhaps in such cases a decision can be made on non-moral grounds; however, the possibility of such a decision serves not to mitigate but to underscore the fact that the separation is unethical. My conclusion, which applies to all three types of cases, is that it is unethical to separate conjoined twins before their developing personalities give some reliable indication as to whether they desire separation and whether they will achieve those goods of conjoinment. (shrink)

What does it mean to respect life and health in an innocent fellow-human being? Separating conjoined twins where one twin will die as a result need not involve the intention to kill or harm. Arguably, however, not all side-effects are “mere” side-effects which could, in principle, be outweighed by sufficiently good intended effects. Rather, foreseen serious harm for an innocent person we non-therapeutically affect can be morally conclusive when linked to the intention to affect the person’s body or (...) invade the space it fills. In the case of infant conjoined twins, such as the Maltese twins Jodie and Mary, the twin who dies from separation has no unjust, or any, intentions as regards the twin saved. She thus has the moral immunity of any innocent person from lethal bodily invasions and other serious bodily harm. Neither the final act which killed Mary nor previous acts of cutting into Mary, including parts shared with her twin Jodie, were therefore morally permissible. (shrink)

Animalism is the doctrine that you and I are animals. Like any substantive philosophical position, animalism faces objections. For example, imagine a case of conjoined twins, where there are two heads, but only one “body,” and where each head seems to have its own typically human and fully discrete mental life. It would be natural to assume that each of the twins is a thing like you and me—each twin is one of us. But it appears that (...) each twin cannot be a distinct human animal, since it appears in this case that there is only one animal. So it appears that animalism renders the wrong verdict in this case. I present two responses to this worry, drawing on Aristotelian claims about the centrality of sensation to animals, and on an account of organism-hood from Maureen and Samuel Condic. I close by considering craniopagus parasiticus and cephalopagus, and show the Aristotelian response is effective in such cases as well. (shrink)

Late last year the English Court of Appeal confirmed a lower court's ruling that doctors could impose an operation to separate recently born conjoined twins, overriding the refusal of consent of their parents. The doctors believed the operation would probably save one of the babies at the cost of killing the other, while not operating would highly probably be followed by the death of both twins within months of their birth. The parents, said to be devout Roman (...) Catholics, believed that it was absolutely wrong to kill one of their babies, even to save the life of the other.Undoubtedly many people, the writer included, would agree with the English courts that the “least worst” option was to separate the twins and save one at the cost of killing the other. But surely many fewer people would have imposed their own resolution of this acute moral dilemma upon parents who conscientiously chose the other limb of the dilemma, refusing to kill one baby even in order to save the other. Were the English judges right, then, to take away the parents' normal right and duty to make health care decisions on behalf of their children and instead impose their own answer to what they admitted to be a terrible dilemma? Describing the two alternatives in terms of choosing between the lesser of two evils on the one hand, and the obligation not to kill on the other, Lord Justice Ward declared, according to The Times law report,1 that: “Parents who were placed on the horns of such a terrible dilemma simply had to choose the lesser of their inevitable loss [sic]”. But that surely is to beg the moral question in favour of the judges' preferred answer to this moral dilemma. The fact is that there are—as …. (shrink)

This article examines the relationship between the principle of double effect and justification for separation surgeries for conjoined twins. First, the principle of double effect is examined in light of its historical context. It is argued that it can only operate under an absolutist view of good and evil that is compatible with the Bible. Given this foundation for application, scenarios for separating conjoined twins are considered against the criteria for the principle of double effect. It (...) is concluded that the principle of double effect cannot be applied to cases wherein one of the twins must be killed. However, it is noted that this does not leave decision makers without options. (shrink)

BackgroundEmergency separation of conjoined twins is performed when one twin is already dead or dying and threatens the survival of the other. The particular decision to perform an emergency separation of conjoined twins provides an ethical dilemma that needs special attention. Adding to the complexity of surgical and postsurgical management in emergency separation, ethical and sociocultural aspects further complicate decision-making.Case presentationFrom 1987 to 2022, 18 conjoined twin separations were performed in our centre. This paper describes (...) three conjoined twin emergency separations. In the first case of thoracoomphalopagus babies at nine days of age, one baby was diagnosed with necrotizing enterocolitis with frequent desaturation and seizures, and the other baby was healthy. Emergency separation was performed on the twelfth day of age; unfortunately, neither baby survived the surgery. In the second case, emergency separation was performed on the 110th day of life due to sepsis in one baby. The nonseptic twin passed away six hours after surgery, while the septic twin died 12 days after surgery due to wound dehiscence and abdominal sepsis. The third case was of an omphalopagus conjoined twin with a parasitic twin. The healthy baby was deemed nonviable but found to be healthy upon birth. Immediate emergency separation was performed at 2 h of age. The living baby survived the surgery but passed away two months later.ConclusionsWhen separation is deemed necessary to save one twin, it becomes difficult to apply standard ethical medical reasoning. The decision to separate results in most cases in very high-risk surgeries with poor outcomes during surgery and postsurgery. Compounded by the complexity of the case, sociocultural and religious aspects further add to the dynamics of decision-making. A multidisciplinary team must work together with a health ethics committee and navigate through this ethical conundrum with the patient and family at its decision-making centre to decide on the best plan of care. (shrink)

This article focuses on the case of conjoined twins in a selection of quodlibetal questions by John Peckham, Henry of Ghent, Remigius dei Girolami and John of Naples, in a period of time between th...

It is commonly taken for granted that abortion is necessarily impermissible if the fetus is a person with a right to life. In her influential essay Judith Jarvis Thomson offers what I will call the violinist example to show that merely having a right to life does not in and of itself give rise in the fetus to a right to use the mother's body. On Thomson's view, if the fetus has a right to use the mother's body that precludes (...) terminating its life by means of an abortion, it is because the mother did something to give the fetus that right. Thus she concludes that the proposition that the fetus is a person does not imply that abortion is morally impermissible. (shrink)

We defend the view that we are not identical to organisms against the objection that it implies that there are two subjects of every conscious state one experiences: oneself and one’s organism. We then criticize animalism —the view that each of us is identical to a human organism—by showing that it has unacceptable implications for a range of actual and hypothetical cases of conjoined twinning : dicephalus, craniopagus parasiticus, and cephalopagus.

In this article, I illustrate ways in which the concepts of the norm and normativity, as well as discourses about normality and the good life, are implicated in relations of power that inform individuals’ values. By analyzing the separation of conjoined twins as a paradigmatic example of practices of overmedicalization, I consider the implications of taking the “goodness” of normality for granted. I argue that overmedicalization procedures establish an interpretative framework that does not leave room for recognizing the (...) contingency of societal suppositions about normality and the good life. It is this kind of ethical reflection (or lack thereof) that I problematize as being symptomatic of individuals’ “normalized” ethical reflection. (shrink)

We attempt to shed light on property rights by examining the case of conjoined twins. We do so since their situation is perhaps among the most challenging of all cases of separating “mine” from “thine.”.

In June 1993, conjoined twins Amy and Angela Lakeberg became the focus of national attention. They shared a complex six‐chambered heart and one liver; only one could survive separation surgery, and even her chances were slim. The medical challenge was great and the ethical challenges were even greater.

Why should all human beings have certain rights simply by virtue of being human? One justification is an appeal to religious authority. However, in increasingly secular societies this approach has its limits. An alternative answer is that human rights are justified through human dignity. This paper argues that human rights and human dignity are better separated for three reasons. First, the justification paradox: the concept of human dignity does not solve the justification problem for human rights but rather aggravates it (...) in secular societies. Second, the Kantian cul-de-sac: if human rights were based on Kant’s concept of dignity rather than theist grounds, such rights would lose their universal validity. Third, hazard by association: human dignity is nowadays more controversial than the concept of human rights, especially given unresolved tensions between aspirational dignity and inviolable dignity. In conclusion, proponents of universal human rights will fare better with alternative frameworks to justify human rights rather than relying on the concept of dignity. (shrink)

This paper is written in response to controversial judicial decisions following separation surgery on conjoined twins “Jodie” and “Mary”. The courts, it is argued, seem to have conceptualised the twins as “entangled singletons” requiring medical intervention to render them physically separate and thus “as they were meant to be”, notwithstanding the death of the weaker twin, “Mary”. In contrast, we argue that certain notions, philosophical and biological, of what human beings are intended to be, are problematic. We (...) consider three compelling conceptualisations of conjoined twins and advocate a model that conceives them as two psychologically separate individuals who happen to share a body, the sharing of a body being integral to the individuality of each twin. While we reject an “essentialist” view of the conjoined state, a view which might render separation surgery unthinkable in all cases, we nevertheless argue against an “adversarial” interpretation of conjoined twins’ respective best interests. We maintain that the physical entanglement should be regarded as a shared problem rather than one posed by one twin to the other. And if, after deliberation, separation surgery is deemed the “least detrimental alternative” or the “lesser of two evils”, then there should be recognition of what conjoined twins will lose, as well as gain, through separation. The current drive to separate twins at all costs may evince a deeper unease with bodily configurations that appear to threaten the premium that the Western ethical and legal tradition places on personal sovereignty, and the physical circumscription that such sovereignty assumes. (shrink)

The article questions the assumption that conjoined twins are necessarily two people or persons by employing arguments based on different points of view: non-personal vitalism, the person as a sentient being, the person as an agent, the person as a locus of narrative and valuation, and the person as an embodied mind. Analogies employed from the cases of amputation, multiple personality disorder, abortion, split-brain patients and cloning. The article further questions the assumption that a conjoined twin's natural (...) interest and wish is separation. I first contend that separation is such a radical procedure as to render the post-separation person different from the pre-separation one. Therefore, it is not possible to benefit the pre-separation twin by the act of separation. The article concludes with a critical evaluation of the tendency in bioethics to regard ethical challenges as rivalry between individuals competing for scarce resources. (shrink)

Why should all human beings have certain rights simply by virtue of being human? One justification is an appeal to religious authority. However, in increasingly secular societies this approach has its limits. An alternative answer is that human rights are justified through human dignity. This paper argues that human rights and human dignity are better separated for three reasons. First, the justification paradox: the concept of human dignity does not solve the justification problem for human rights but rather aggravates it (...) in secular societies. Second, the Kantian cul-de-sac: if human rights were based on Kant's concept of dignity rather than theist grounds, such rights would lose their universal validity. Third, hazard by association: human dignity is nowadays more controversial than the concept of human rights, especially given unresolved tensions between aspirational dignity and inviolable dignity. In conclusion, proponents of universal human rights will fare better with alternative frameworks to justify human rights rather than relying on the concept of dignity. (shrink)

The principle of double effect is often used in bioethics as a tool to evaluate significant cases in obstetrics and gynecology. In this article the author, a Catholic priest, presents and interprets St. Thomas Aquinas’s delineation of the principle and discusses several classical applications, namely, to hysterectomy during pregnancy, ectopic pregnancy, and craniotomy. He explains the medical anatomy and physiology of the conjoined Maltese twins, Jodie and Mary, and then examines the arguments of four moralists on their separation. (...) He concludes by arguing that the principle morally justified the surgical separation of Jodie and Mary. National Catholic Bioethics Quarterly 9.1 : 85–96. (shrink)