Symbols of Power: Adinkras and the Nature of Reality

Philosophy

physicsworld.com Volume 23 No 6 June 2010 Symbols of power Adinkras and the nature of reality Cell control Fighting cancer with physics Fits and starts Why randomness does not rule our lives Who, what, when? Deciding upon a discovery In the land of theoretical physics, equations have always been king. Indeed, it would probably be fair to caricature theoretical physicists as members of a company called "Equations-R-Us", since we tend to view new equations as markers of progress. The modern era of equation prediction began with Maxwell in 1861, continued through the development of Einstein's equations of general relativity in 1916 and reached its first peak in the 1920s with the Schrödinger and Dirac equations. Then a second, postwar surge saw the development of equations describing the strong force and the electroweak force, culminating in the creation of the Standard Model of particle physics in about 1973. The equations trend continues today, with the ongoing struggle to create comprehensive equations to describe superstring theory. This effort – which aims to incorporate the force of gravity into physical models in a way that the Standard Model does not – marks the extant boundary of a long tradition. Yet equations are not the only story. To an extent, geometrical representations of physical theories have also been useful when correctly applied. The most famous incorrect geometrical representation in physics is probably Johannes Kepler's model of planetary orbits; initially, Kepler believed the orbits could be described by five regular polygons successively embedded within each other, but he abandoned this proposition when more accurate data became available. A less well known but much more successful example of geometry applied to physics is Murray Gell-Mann's "eightfold way", which is a means of organizing subatomic particles. This organization has an underlying explanation using triangles with quarks located at the vertices. For the past five years, I and a group of my colleagues (including Charles Doran, Michael Faux, Tristan Hubsch, Kevin Iga, Greg Landweber and others) have been following the geometric-physics path pioneered by Kepler and Gell-Mann. The geometric objects that interest us are not triangles or octagons, but more complicated figures known as "adinkras", a name Faux suggested. The word "adinkra" is of West African etymology, and it originally referred to visual symbols created by the Akan people of Ghana and the Gyamen of Côte d'Ivoire to represent concepts or aphorisms. However, the mathematical adinkras we study are really only linked to those African symbols by name. Even so, it must be acknowledged that, like their forebears, mathematical adinkras also represent concepts that are difficult to express in words. Most intriguingly, they may even contain hints of something more profound – including the idea that our universe could be a computer simulation, as in the Matrix films. If you knew SUSY like we know SUSY... To understand what adinkras are, we must first examine the physical theory to which they relate: supersymmetry, commonly abbreviated as SUSY. The concept of symmetry is ubiquitous in nature, but on a more technical level it has been a powerful mathematical tool for the development of equations. Einstein recognized that there was a symmetry between the effects observed by someone in an accelerating spacecraft far away from all planets and those observed by someone standing on the planet's surface. He called this recognition the "happiest thought" of his life, and he used it to determine the form of his equations of general relativity, which describe how matter warps space and time to create gravity. Moving on to the Standard Model, the set of equations used to describe the physics of quarks, leptons (the family of particles that contains the electron) and force-carrying particles like the photon (carrier of the electromagnetic force) is also largely determined by symmetry groups. Photons, for example, possess a type of symmetry known as U(1), which means that two distinct photons can produce the same electric and magnetic forces on a charged particle. Another important symmetry is the SU(3) symmetry of quarks, which can be visualized using what mathematicians call a "weightspace diagram" (figure 1). This diagram shows the entire family of nuclear particles of which the proton, p, and neutron, n, are members. The location of particles in this diagram is determined by particle properties called isospin and strangeness, the values of which were first measured in the 1950s and 1960s. Six triangles lurk inside it – you can see them if you draw lines from the centre to each vertex – and this "triangular" symmetry is part of what leads to the designation SU(3). Such diagrams are more than pictures. In fact, it was an insight drawn from such diagrams that led Physicists have long sought to describe the universe in terms of equations. Now, James Gates explains how research on a class of geometric symbols known as adinkras could lead to fresh insights into the theory of supersymmetry – and perhaps even the very nature of reality Symbols of power Like their African forebears, mathematical adinkras represent concepts that are difficult to express in words, and they may even contain hints of something more profound James Gates is a theoretical physicist at the University of Maryland, US, e-mail gatess@ wam.umd.edu physicsworld.comFeature: Physics and geometry 34 Physics World June 2010 Gell-Mann and George Zweig to a new understanding of nuclear matter. Gell-Mann and Zweig realized that patterns in diagrams showing families of nuclear particles meant that those particles must be made up of smaller, more fundamental particles: quarks. The nuclear-particle octet diagram gets its name because there are particles associated with each of its six vertices, and two additional particles associated with its centre, hence an "octet" of particles. This diagram is useful as a kind of accounting tool: in certain nuclear reactions, two or more experiments will lead to simply related results if one member of this family is replaced by another. For example, measuring how a proton is deflected from a neutron by the strong nuclear force will yield a result that is directly related to the deflection of a Σ– particle from a neutron. This is the power of using symmetries. When we know that certain symmetries are present in nature, we can use one experiment to predict the outcome of many others. As its name implies, the theory of supersymmetry takes the idea of symmetry a step further. In the Standard Model there is a dichotomy between leptons and quarks – collectively called "matter particles" – and force-carrying particles like photons. All matter particles are fermions, particles with half-integer quantum spin that obey the Pauli exclusion principle. Forcecarrying particles, in contrast, are bosons, which have integer spin and can violate the exclusion principle. This means that not only photons but also gluons (which carry the strong nuclear force), the W and Z bosons (which carry the weak nuclear force), and even the hypothetical Higgs boson are all free to possess any Complex ideas, complex shapes Adinkras – geometric objects that encode mathematical relationships between supersymmetric particles – are named after symbols that represent wise sayings in West African culture. This adinkra is called "nea onnim no sua a, ohu", which translates as "he who does not know can become knowledgeable through learning". M a t W a rd physicsworld.com Feature: Physics and geometry 35Physics World June 2010 allowed quantum numbers in composite systems. SUSY breaks this rule that all matter particles are fermions and all carriers are bosons. It does this by relating each Standard Model particle to a new form of matter and energy called a "superpartner". In its simplest form, SUSY states that every boson has a corresponding "super-fermion" associated with it, and vice versa. These superpartners have not yet been observed in nature, but one of the main tasks of CERN's Large Hadron Collider (LHC) will be to look for experimental evidence of their existence. If the LHC finds these superpartners, then the Standard Model will have to be replaced by the Minimal Supersymmetric Standard Model (MSSM), or perhaps another more exotic variant. From the point of view of equations, however, SUSY presents an additional challenge. Even if the LHC finds evidence that we live in a supersymmetric universe, there are many different sets of equations that incorporate supersymmetry. How, then, do we pick the right ones? The answer, of course, is that we pick the equations that agree with experimental observations. However, we can also ask a more subtle question: how do we ensure that the SUSY property is made manifest at every stage of calculations involving the quantum behaviour of these equations? It is here that adinkras might prove useful. Just as a weight-space diagram is a graphical representation that precisely encodes the mathematical relations between the members of SU(3) families, so an adinkra is a graphical representation that precisely encodes the mathematical relations between the members of supersymmetry families. Building up adinkras Now that we know a little bit about how adinkras can be used, we can begin to discuss what they look like. All adinkras are constructed by starting with squares, cubes and their higher-dimensional generalizations; these structures provide a "skeleton" that is then "decorated" by additional operations. Each of these decorations has a mathematical significance, which I will discuss later. For the moment, let us just concentrate on building a simple adinkra. To make a square into an adinkra, we begin by placing a white dot at one vertex (figure 2). The rules of adinkras then dictate that the two line segments connected to the white dot must have black dots at their opposite ends. This means that the final unpopulated vertex is connected to "black dot" vertices, so it must be populated by a white dot. Next, we need to assign directions to each line segment, or link. To keep track of these different directions, we assign distinct colours to each of them: all links that point in the same direction are assigned the same colour, and links that point in different directions are never assigned the same colour. Then, we need to assign an "edge-parity" to each link: each coloured line can be drawn as either solid or dashed. Every two-colour closed path in an adinkra must contain an odd number of dashed links. One last rule is that white dots and black dots are never allowed to have the same vertical position; that is, no black dot in an adinkra is ever allowed to appear at the same height as a white dot. Figure 2 shows a square that has been "decorated" in two different ways and made into two distinct adinkras. There is no limit to the number of colours that may be used to construct an adinkra. As a result, higherdimensional adinkras have a certain aesthetic appeal (figure 3). As Einstein once said, "After a certain high level of technical skill is achieved, science and art tend to coalesce in aesthetics, plasticity and form." Perhaps the "artistic" depictions shown here are an example of this. But adinkras, like Gell-Mann's octets, are not just pictures. In fact, they are in some ways rather similar to Feynman diagrams, which are the series of line drawings used to describe calculations in quantum electrodynamics. Like Feynman diagrams, adinkras are a This weight-space diagram shows the "baryon octet" group of particles, including the proton (p), neutron (n) and six more exotic species known as hyperons. Particles are arranged according to their isospin (how they interact with the strong nuclear force) and the number of strange quarks they contain (their "strangeness"). n p Σ– Σ+ Σ0 Λ Ξ0Ξ– 1 Weight-space diagrams Ψ2 Φ2 Φ1 Ψ1 D2 D2 D1 D1 Ψ1 Φ1 Φ2 D2 D1D1 D2 Ψ2 D1Φ1 = iΨ1 D1Φ2 = iΨ2 D1Ψ1 = ∂TΦ1 D1Ψ2 = ∂TΦ2 D2Φ1 = iΨ2 D2Φ2 = – iΨ1 D2Ψ1 = –∂TΦ2 D2Ψ2 = ∂TΦ1 A square can be transformed into two distinct adinkras. The set of eight super-differential equations relates to the bottom adinkra. 2 From squares to adinkras physicsworld.comFeature: Physics and geometry 36 Physics World June 2010 precise mathematical description of calculations. They also serve as an aid to performing these calculations, since the way that adinkras are constructed provides a streamlined description of the most compact sets of equations with the SUSY property. But while Feynman diagrams describe calculations for particle quantum behaviour, adinkras are connected instead to mathematical objects known as Clifford algebras and superdifferential equations. Clifford algebras were introduced by the English mathematician and philosopher William Kingdom Clifford in the 1870s as mathematical constructions that generalize complex numbers. However, they also provide the mathematical basis for our modern understanding of fermions. Where adinkras are concerned, if one ignores the information contained in the vertical height of the same type of dots in an adinkra, then that adinkra provides an exact description of mathematical matrices associated with Clifford algebras. For example, using the rules associated with adinkras, the bottom adinkra in figure 2 yields two of the three "Pauli matrices" (elements of a Clifford algebra) that describe the spin states of fermions. A second connection to mathematics is even more similar to Feynman diagrams. It can be shown that each adinkra corresponds to a distinct set of super-differential equations. Super-differential equations involve both the ordinary derivative operator (invented by Newton and Leibnitz) and a newer type of operator called a "super derivative", which was invented in the mid-1970s by the mathematician Felix Berezin and then elaborated on by the physicists Abdus Salam and John Strathdee. Super derivatives, represented by the links in an adinkra, are similar to the ordinary derivative, except that they are allowed to violate the usual product rule for derivatives. The super-differential equations for the bottom adinkra derived from a square are shown in figure 2. Since there are only two types of coloured links, there are only two super derivatives: D1 associated with green links and D2 associated with red links. We also have two bosonic superfunctions (Φ1 and Φ2) associated with the correspondingly labelled white dots and two fermionic superfunctions (Ψ1 and Ψ2) associated with the correspondingly labelled black dots. As complex numbers generally consist of both a real and imaginary part, a superfunction consists of both bosonic and fermionic parts. To turn these components of the adinkra into a set of equations, we begin by picking one dot – let's use the bottom-left one as an example – and writing its associated superfunction, Φ1, to the left of an equal sign. Next, we choose one of the coloured links and write its associated D to the left of the superfunction. For the green link this would be D1; for the red link it would be D2. Then we look to see what dot is at the other end of this link. If we pick the green link, the "target dot" is the one associated with the superfunction Ψ1, so this symbol belongs on the right of the equals sign. These rules alone are enough to give us the upper four equations in figure 2. To "derive" the second group of four equations we need to introduce the ordinary differential operation, denoted by . The manner in which it appears in the equations is controlled by the relative height of the dots within each diagram: whenever the "starting" dot is higher in the adinkra than the "target" dot, this ordinary derivative appears on the right-hand side of the corresponding equation. The dashed links simply insert minus signs into some equations. You should have enough information now to apply this analysis to the second diagram in order to write down its associated equations – although, in time-honoured fashion, I have left this as an exercise for the reader. SUSY and adinkras Returning now to the concept of supersymmetry, Salam and Strathdee devised a simple test to determine when systems of equations possess the property of SUSY. The system shown in figure 2 easily passes Salam and Strathdee's test, but this does not necessarily mean that they are the equations that theorists from the Equations-R-Us company are seeking. In fact, they are not: aside from the Pauli matrices, the square-derived adinkras are just too simple to be associated with differential equations that have physical meaning. The same is true for adinkras based on a 3D cube. However, with a 4D hypercube, or tesseract, it is a different story. The four-colour adinkra (figure 4) demonstrates a behaviour that is not present for adinkras with fewer colours: it can be broken into two separate, smaller adinkras. These smaller adinkras do have physical meaning. The one on the far right is in fact related to Maxwell's equations. If one first removes the uppermost open dot and then performs the Salam–Strathdee test, then Maxwell's equations involving current charges emerge. Similarly, removing the two uppermost dots from the centre adinkra followed by the Salam–Strathdee test leads to the These large n-colour folded adinkras represent complex systems of super-differential equations. 3 Multidimensional adinkras G re g o ry D L a n d w e b e r physicsworld.com Feature: Physics and geometry 37Physics World June 2010 equations for the behaviour of the electron and its SUSY partner (known as the "selectron"). Some of the equations described here have been known for some time to physicists who study SUSY. Yet it was not until 2009 that research on adinkras (arXiv:0902.3830) showed that these geometric objects can mimic the behaviour of the equations, and thus provided the first evidence that adinkras could be related to physics. The next key question to answer is whether the reverse process can also occur – beginning with an adinkra and using it to derive, via a set of welldefined rules, something like the Maxwell or Dirac equations. In 2001 (arXiv:hep-th/0109109) my students and I conjectured that this could indeed be the case, but only if we could encode the properties of 4D equations onto objects in a mathematical 1D format. Though this conjecture has not yet been proven, work completed by Faux, Iga and Landweber in 2009 (arXiv:0907.4543, arXiv:0907.3605) has provided the strongest evidence to date of its correctness. So, just as weight-space diagrams opened a new way to conceptualize the physics of nuclear matter, it is conceivable that adinkras may yield an entirely new way to formulate theories that possess the property of SUSY. From theoretical physics to codes As it turns out, it is not just four-colour adinkras that can be separated into two smaller adinkras with the same number of colours; adinkras with more than four colours also possess this property of separability. But why does this occur only for four or more colours? Investigating this question launched our "treasure hunt" in a completely unexpected direction: computer codes. Modern computer and communication technologies have come to prominence by transmitting data rapidly and accurately. These data consist principally of strings of ones and zeros (called bits) written in long sequences called "words". When these computer words are transmitted from a source to a receiver, there is always the chance that static noise in the system can alter the content of any word. Hence, the transmitted word might arrive at the receiver as pure gibberish. One of the first people to confront this problem was the mathematician Richard Hamming, who worked on the Manhattan Project during the Second World War. In 1950 he introduced the idea of "error-correcting codes" that could remove or work around any unwanted changes to a transmitted signal. Hamming's idea was for the sending computer to insert extra bits into words in a specific manner such that the receiving computer could, by looking at the extra bits, detect and correct errors introduced by the transmission process. His algorithm for the insertion of these extra bits is known as the "Hamming code". The construction of such error-correcting codes has been pursued since the beginning of the computer age and many different codes now exist. These are typically divided into families; for example, the "check-sum extended Hamming code" is a rather complicated variant of the Hamming code and it belongs to a family known as "doubly even self-dual linear binary error-correcting block codes" (an amazing mouthful!). Yet whatever family they belong to, all error-correction codes serve the same function: they are used to detect errors and allow the correct transmission of digital data. How does this relate to adinkras? The middle adinkra in figure 4 is obtained by folding the image on the left of the figure. The folding involves taking pairs of the dots of the same type and "fusing them together" as if they were made of clay. In general, an adinkrafolding process will lead to diagrams where the associated equations do not possess the SUSY property. In order to ensure that this property is retained, we must carry out the fusing in such a way that white dots are only fused with other white dots, black dots with other black dots, and lines of a given colour and dashing are only joined with lines that possess the same properties. Most foldings violate this, but there is one exception – and it happens to be related to a folding that involves doubly even self-dual linear binary error-correcting block codes. The adinkra in figure 5 is the same as the left-hand part of figure 4 but for simplicity it is shown without dashed edges. We pick the bottom dot as a starting point and assign it an address of (0000). To move to any of the dots at the second level requires traversing one of the coloured links. There are four distinct ways in which this can be done. To move to any dot at the third level from the bottom dot requires the use of two different coloured links, and so on for the rest of the adinkra. In this way, every dot is assigned an address, from (0000) to (1111). These sequences of ones and zeros are binary computer words. To accomplish the folding that maintains the SUSY The "decorated tesseract" adinkra on the left can be broken down into two separate adinkras. The author's collaboration of mathematicians and other physicists has introduced the name "gnomoning" for this process of subtracting a smaller adinkra from larger ones. The word gnomoning was used by Euclid, the founder of geometry, to describe a plane figure obtained by removing a smaller figure that is similar to the larger one. + 4 Adinkras within adinkras Adinkras may yield an entirely new way to formulate theories that possess the property of supersymmetry physicsworld.comFeature: Physics and geometry 38 Physics World June 2010 property in the associated equations, we must begin by squeezing the bottom dot together with the upper dot. When their addresses are added bit-wise to one another, this yields the sequence (1111). If we continue this folding process, always choosing pairs of dots so that their associated "words" sum bit-wise to (1111), we can transform the adinkra on the left-hand side of figure 4 to the one on the right. Thus, maintaining the equations' SUSY property requires that the particular sequence of bits given by (1111) be used in the folding process. The process used to meet this criterion happens to correspond to the simplest member of the family containing the check-sum extended Hamming code. The part of science that deals with the transmission of data is called information theory. For the most part, this is a science that has largely developed in ways that are unrelated to the fields used in theoretical physics. However, with the observation that structures from information theory – codes – control the structure of equations with the SUSY property, we may be crossing a barrier. I know of no other example of this particular intermingling occurring at such a deep level. Could it be that codes, in some deep and fundamental way, control the structure of our reality? In asking this question, we may be ending our "treasure hunt" in a place that was anticipated previously by at least one pioneering physicist: John Archibald Wheeler. Life in the Matrix? Wheeler, who died in 2008, was an extremely wellregarded figure within physics. He served as advisor to a clutch of important physicists, including Richard Feynman, while his own work included the concept of the "S-matrix" (a mathematical tool that helps us understand Standard Model particles). Beyond the physics community, Wheeler is probably best known for coining the terms "black hole" and "wormhole". But he also coined a slightly less familiar phrase – "it from bit" – and this is what concerns us here. The idea of "it from bit" is a complex one, and Wheeler's own description of it is probably still the best. In 1990 he suggested that "every 'it' – every particle, every field of force, even the space–time continuum itself – derives its function, its meaning, its very existence entirely...from the apparatus-elicited answers to yes-or-no questions, binary choices, bits". The "it from bit" principle, he continued, "symbolizes the idea that every item of the physical world has at bottom...an immaterial source and explanation: that which we call reality arises in the last analysis from the posing of yes–no questions and the registering of equipmentevoked responses; in short, that all things physical are information-theoretic in origin and that this is a participatory universe". When I first heard the idea of "it from bit" as a young physicist, I thought Wheeler must be crazy. The concept of a world made up of information just sounded strange, and (although I did not know it at the time) I was not the only one who thought so. However, sometimes crazy ideas turn out to be true, and Wheeler has been proved right before. As Feynman said, "When I was [Wheeler's] student, I discovered that if you take one of his crazy ideas and you unwrap the layers of craziness from it one after another, like lifting layers off an onion, at the heart of the idea you will often find a powerful kernel of truth." Indeed, another of Wheeler's "crazy" ideas – his suggestion that a positron can be treated as an electron moving backwards in time – played a role in Feynman later winning a Nobel prize. As for my own collaboration on adinkras, the path my colleagues and I have trod since the early 2000s has led me to conclude that codes play a previously unsuspected role in equations that possess the property of supersymmetry. This unsuspected connection suggests that these codes may be ubiquitous in nature, and could even be embedded in the essence of reality. If this is the case, we might have something in common with the Matrix science-fiction films, which depict a world where everything human beings experience is the product of a virtual-reality-generating computer network. If that sounds crazy to you – well, you could be right. It is certainly possible to overstate mathematical links between different systems: as the physicist Eugene Wigner pointed out in 1960, just because a piece of mathematics is ubiquitous and appears in the description of several distinct systems does not necessarily mean that those systems are related to each other. The number π , after all, occurs in the measurement of circles as well as in the measurement of population distributions. This does not mean that populations are related to circles. Yet for a moment, let us imagine that this alternative Matrix-style world contains some theoretical physicists, and that one of them asks, "How could we discover whether we live inside a Matrix?". One answer might be "Try to detect the presence of codes in the laws that describe physics." I leave it to you to decide whether Wigner's warning should be applied to the theoretical physicists living in the Matrix – and to us. ■ The decorated-tesseract adinkra and its associated computer "words". For simplicity, the adinkra is shown without dashed lines. (1111) (1110) (1101) (1011) (0111) (1100) (1001) (0110) (1010) (0101) (0011) (1000) (0100) (0010) (0001) (0000) 5 Coded adinkras physicsworld.com Feature: Physics and geometry 39Physics World June


Section A: Abortion

Philosophy

After-birth abortion: why should the baby live? Alberto Giubilini,1 Francesca Minerva2 1Centre for Applied Philosophy and Public Ethics, Charles Sturt University, Canberra, Australian Capital Territory, Australia 2Centre for Applied Philosophy and Public Ethics, University of Melbourne, Melbourne, Victoria, Australia Correspondence to Dr Francesca Minerva, CAPPE, University of Melbourne, Melbourne, VIC 3010, Australia; francesca.minerva@unimelb. edu.au Received 25 November 2011 Revised 26 January 2012 Accepted 27 January 2012 Published Online First 23 February 2012 To cite: Giubilini A, Minerva F. J Med Ethics 2013;39:261–263. ABSTRACT Abortion is largely accepted even for reasons that do not have anything to do with the fetus' health. By showing that (1) both fetuses and newborns do not have the same moral status as actual persons, (2) the fact that both are potential persons is morally irrelevant and (3) adoption is not always in the best interest of actual people, the authors argue that what we call 'after-birth abortion' (killing a newborn) should be permissible in all the cases where abortion is, including cases where the newborn is not disabled. INTRODUCTION Severe abnormalities of the fetus and risks for the physical and/or psychological health of the woman are often cited as valid reasons for abortion. Sometimes the two reasons are connected, such as when a woman claims that a disabled child would represent a risk to her mental health. However, having a child can itself be an unbearable burden for the psychological health of the woman or for her already existing children,1 regardless of the condition of the fetus. This could happen in the case of a woman who loses her partner after she finds out that she is pregnant and therefore feels she will not be able to take care of the possible child by herself. A serious philosophical problem arises when the same conditions that would have justified abortion become known after birth. In such cases, we need to assess facts in order to decide whether the same arguments that apply to killing a human fetus can also be consistently applied to killing a newborn human. Such an issue arises, for example, when an abnormality has not been detected during pregnancy or occurs during delivery. Perinatal asphyxia, for instance, may cause severe brain damage and result in severe mental and/or physical impairments comparable with those for which a woman could request an abortion. Moreover, abnormalities are not always, or cannot always be, diagnosed through prenatal screening even if they have a genetic origin. This is more likely to happen when the disease is not hereditary but is the result of genetic mutations occurring in the gametes of a healthy parent. One example is the case of Treacher-Collins syndrome (TCS), a condition that affects 1 in every 10 000 births causing facial deformity and related physiological failures, in particular potentially life-threatening respiratory problems. Usually those affected by TCS are not mentally impaired and they are therefore fully aware of their condition, of being different from other people and of all the problems their pathology entails. Many parents would choose to have an abortion if they find out, through genetic prenatal testing, that their fetus is affected by TCS. However, genetic prenatal tests for TCS are usually taken only if there is a family history of the disease. Sometimes, though, the disease is caused by a gene mutation that intervenes in the gametes of a healthy member of the couple. Moreover, tests for TCS are quite expensive and it takes several weeks to get the result. Considering that it is a very rare pathology, we can understand why women are not usually tested for this disorder. However, such rare and severe pathologies are not the only ones that are likely to remain undetected until delivery; even more common congenital diseases that women are usually tested for could fail to be detected. An examination of 18 European registries reveals that between 2005 and 2009 only the 64% of Down's syndrome cases were diagnosed through prenatal testing.2 This percentage indicates that, considering only the European areas under examination, about 1700 infants were born with Down's syndrome without parents being aware of it before birth. Once these children are born, there is no choice for the parents but to keep the child, which sometimes is exactly what they would not have done if the disease had been diagnosed before birth. ABORTION AND AFTER-BIRTH ABORTION Euthanasia in infants has been proposed by philosophers3 for children with severe abnormalities whose lives can be expected to be not worth living and who are experiencing unbearable suffering. Also medical professionals have recognised the need for guidelines about cases in which death seems to be in the best interest of the child. In The Netherlands, for instance, the Groningen Protocol (2002) allows to actively terminate the life of 'infants with a hopeless prognosis who experience what parents and medical experts deem to be unbearable suffering'.4 Although it is reasonable to predict that living with a very severe condition is against the best interest of the newborn, it is hard to find definitive arguments to the effect that life with certain pathologies is not worth living, even when those pathologies would constitute acceptable reasons for abortion. It might be maintained that 'even allowing for the more optimistic assessments of the potential of Down's syndrome children, this potential cannot be said to be equal to that of a normal child'.3 But, in fact, people with Down's syndrome, as well as people affected by many other severe disabilities, are often reported to be happy.5 Nonetheless, to bring up such children might be an unbearable burden on the family and on society as a whole, when the state economically provides for their care. On these grounds, the fact that a fetus has the potential to become a person who will have an (at least) acceptable life is no reason for prohibiting abortion. Therefore, we argue that, when circumstances occur after birth such that they would have justified abortion, what we call after-birth abortion should be permissible. In spite of the oxymoron in the expression, we propose to call this practice 'after-birth abortion', rather than 'infanticide', to emphasise that the moral Giubilini A, et al. J Med Ethics 2013;39:261–263. doi:10.1136/medethics-2011-100411 261 Featured article group.bmj.com on June 25, 2015 Published by http://jme.bmj.com/Downloaded from status of the individual killed is comparable with that of a fetus (on which 'abortions' in the traditional sense are performed) rather than to that of a child. Therefore, we claim that killing a newborn could be ethically permissible in all the circumstances where abortion would be. Such circumstances include cases where the newborn has the potential to have an (at least) acceptable life, but the well-being of the family is at risk. Accordingly, a second terminological specification is that we call such a practice 'after-birth abortion' rather than 'euthanasia' because the best interest of the one who dies is not necessarily the primary criterion for the choice, contrary to what happens in the case of euthanasia. Failing to bring a new person into existence cannot be compared with the wrong caused by procuring the death of an existing person. The reason is that, unlike the case of death of an existing person, failing to bring a new person into existence does not prevent anyone from accomplishing any of her future aims. However, this consideration entails a much stronger idea than the one according to which severely handicapped children should be euthanised. If the death of a newborn is not wrongful to her on the grounds that she cannot have formed any aim that she is prevented from accomplishing, then it should also be permissible to practise an after-birth abortion on a healthy newborn too, given that she has not formed any aim yet. There are two reasons which, taken together, justify this claim: 1. The moral status of an infant is equivalent to that of a fetus, that is, neither can be considered a 'person' in a morally relevant sense. 2. It is not possible to damage a newborn by preventing her from developing the potentiality to become a person in the morally relevant sense. We are going to justify these two points in the following two sections. THE NEWBORN AND THE FETUS ARE MORALLY EQUIVALENT The moral status of an infant is equivalent to that of a fetus in the sense that both lack those properties that justify the attribution of a right to life to an individual. Both a fetus and a newborn certainly are human beings and potential persons, but neither is a 'person' in the sense of 'subject of a moral right to life'. We take 'person' to mean an individual who is capable of attributing to her own existence some (at least) basic value such that being deprived of this existence represents a loss to her. This means that many non-human animals and mentally retarded human individuals are persons, but that all the individuals who are not in the condition of attributing any value to their own existence are not persons. Merely being human is not in itself a reason for ascribing someone a right to life. Indeed, many humans are not considered subjects of a right to life: spare embryos where research on embryo stem cells is permitted, fetuses where abortion is permitted, criminals where capital punishment is legal. Our point here is that, although it is hard to exactly determine when a subject starts or ceases to be a 'person', a necessary condition for a subject to have a right to X is that she is harmed by a decision to deprive her of X. There are many ways in which an individual can be harmed, and not all of them require that she values or is even aware of what she is deprived of. A person might be 'harmed' when someone steals from her the winning lottery ticket even if she will never find out that her ticket was the winning one. Or a person might be 'harmed' if something were done to her at the stage of fetus which affects for the worse her quality of life as a person (eg, her mother took drugs during pregnancy), even if she is not aware of it. However, in such cases we are talking about a person who is at least in the condition to value the different situation she would have found herself in if she had not been harmed. And such a condition depends on the level of her mental development,6 which in turn determines whether or not she is a 'person'. Those who are only capable of experiencing pain and pleasure (like perhaps fetuses and certainly newborns) have a right not to be inflicted pain. If, in addition to experiencing pain and pleasure, an individual is capable of making any aims (like actual human and non-human persons), she is harmed if she is prevented from accomplishing her aims by being killed. Now, hardly can a newborn be said to have aims, as the future we imagine for it is merely a projection of our minds on its potential lives. It might start having expectations and develop a minimum level of selfawareness at a very early stage, but not in the first days or few weeks after birth. On the other hand, not only aims but also welldeveloped plans are concepts that certainly apply to those people (parents, siblings, society) who could be negatively or positively affected by the birth of that child. Therefore, the rights and interests of the actual people involved should represent the prevailing consideration in a decision about abortion and after-birth abortion. It is true that a particular moral status can be attached to a nonperson by virtue of the value an actual person (eg, the mother) attributes to it. However, this 'subjective' account of the moral status of a newborn does not debunk our previous argument. Let us imagine that a woman is pregnant with two identical twins who are affected by genetic disorders. In order to cure one of the embryos the woman is given the option to use the other twin to develop a therapy. If she agrees, she attributes to the first embryo the status of 'future child' and to the other one the status of a mere means to cure the 'future child'. However, the different moral status does not spring from the fact that the first one is a 'person' and the other is not, which would be nonsense, given that they are identical. Rather, the different moral statuses only depends on the particular value the woman projects on them. However, such a projection is exactly what does not occur when a newborn becomes a burden to its family. THE FETUS AND THE NEWBORN ARE POTENTIAL PERSONS Although fetuses and newborns are not persons, they are potential persons because they can develop, thanks to their own biological mechanisms, those properties which will make them 'persons' in the sense of 'subjects of a moral right to life': that is, the point at which they will be able to make aims and appreciate their own life. It might be claimed that someone is harmed because she is prevented from becoming a person capable of appreciating her own being alive. Thus, for example, one might say that we would have been harmed if our mothers had chosen to have an abortion while they were pregnant with us7 or if they had killed us as soon as we were born. However, whereas you can benefit someone by bringing her into existence (if her life is worth living), it makes no sense to say that someone is harmed by being prevented from becoming an actual person. The reason is that, by virtue of our definition of the concept of 'harm' in the previous section, in order for a harm to occur, it is necessary that someone is in the condition of experiencing that harm. If a potential person, like a fetus and a newborn, does not become an actual person, like you and us, then there is neither an actual nor a future person who can be harmed, which means that there is no harm at all. So, if you ask one of us if we would have been harmed, had our parents decided to kill us when we were fetuses or newborns, our answer is 'no', because they would have harmed someone who does not exist (the 'us' 262 Giubilini A, et al. J Med Ethics 2013;39:261–263. doi:10.1136/medethics-2011-100411 Featured article group.bmj.com on June 25, 2015 Published by http://jme.bmj.com/Downloaded from whom you are asking the question), which means no one. And if no one is harmed, then no harm occurred. A consequence of this position is that the interests of actual people over-ride the interest of merely potential people to become actual ones. This does not mean that the interests of actual people always over-ride any right of future generations, as we should certainly consider the well-being of people who will inhabit the planet in the future. Our focus is on the right to become a particular person, and not on the right to have a good life once someone will have started to be a person. In other words, we are talking about particular individuals who might or might not become particular persons depending on our choice, and not about those who will certainly exist in the future but whose identity does not depend on what we choose now. The alleged right of individuals (such as fetuses and newborns) to develop their potentiality, which someone defends,8 is overridden by the interests of actual people (parents, family, society) to pursue their own well-being because, as we have just argued, merely potential people cannot be harmed by not being brought into existence. Actual people's well-being could be threatened by the new (even if healthy) child requiring energy, money and care which the family might happen to be in short supply of. Sometimes this situation can be prevented through an abortion, but in some other cases this is not possible. In these cases, since non-persons have no moral rights to life, there are no reasons for banning after-birth abortions. We might still have moral duties towards future generations in spite of these future people not existing yet. But because we take it for granted that such people will exist (whoever they will be), we must treat them as actual persons of the future. This argument, however, does not apply to this particular newborn or infant, because we are not justified in taking it for granted that she will exist as a person in the future. Whether she will exist is exactly what our choice is about. ADOPTION AS AN ALTERNATIVE TO AFTER-BIRTH ABORTION? A possible objection to our argument is that after-birth abortion should be practised just on potential people who could never have a life worth living.9 Accordingly, healthy and potentially happy people should be given up for adoption if the family cannot raise them up. Why should we kill a healthy newborn when giving it up for adoption would not breach anyone's right but possibly increase the happiness of people involved (adopters and adoptee)? Our reply is the following. We have previously discussed the argument from potentiality, showing that it is not strong enough to outweigh the consideration of the interests of actual people. Indeed, however weak the interests of actual people can be, they will always trump the alleged interest of potential people to become actual ones, because this latter interest amounts to zero. On this perspective, the interests of the actual people involved matter, and among these interests, we also need to consider the interests of the mother who might suffer psychological distress from giving her child up for adoption. Birthmothers are often reported to experience serious psychological problems due to the inability to elaborate their loss and to cope with their grief.10 It is true that grief and sense of loss may accompany both abortion and after-birth abortion as well as adoption, but we cannot assume that for the birthmother the latter is the least traumatic. For example, 'those who grieve a death must accept the irreversibility of the loss, but natural mothers often dream that their child will return to them. This makes it difficult to accept the reality of the loss because they can never be quite sure whether or not it is irreversible'.11 We are not suggesting that these are definitive reasons against adoption as a valid alternative to after-birth abortion. Much depends on circumstances and psychological reactions. What we are suggesting is that, if interests of actual people should prevail, then after-birth abortion should be considered a permissible option for women who would be damaged by giving up their newborns for adoption. CONCLUSIONS If criteria such as the costs (social, psychological, economic) for the potential parents are good enough reasons for having an abortion even when the fetus is healthy, if the moral status of the newborn is the same as that of the foetus and if neither has any moral value by virtue of being a potential person, then the same reasons which justify abortion should also justify the killing of the potential person when it is at the stage of a newborn. Two considerations need to be added. First, we do not put forward any claim about the moment at which after-birth abortion would no longer be permissible, and we do not think that in fact more than a few days would be necessary for doctors to detect any abnormality in the child. In cases where the after-birth abortion were requested for nonmedical reasons, we do not suggest any threshold, as it depends on the neurological development of newborns, which is something neurologists and psychologists would be able to assess. Second, we do not claim that after-birth abortions are good alternatives to abortion. Abortions at an early stage are the best option, for both psychological and physical reasons. However, if a disease has not been detected during the pregnancy, if something went wrong during the delivery, or if economical, social or psychological circumstances change such that taking care of the offspring becomes an unbearable burden on someone, then people should be given the chance of not being forced to do something they cannot afford. Correction notice This article has been corrected since it was published Online First. The first author's affiliations have been corrected. Acknowledgements We would like to thank Professor Sergio Bartolommei, University of Pisa, who read an early draft of this paper and gave us very helpful comments. The responsibility for the content remains with the authors. Contributors AG and FM contributed equally to the manuscript. Competing interests None. Provenance and peer review Not commissioned; externally peer reviewed. REFERENCES 1 Abortion Act. London: Stationery Office, 1967. 2 European Surveillance of Congenital Anomalies. EUROCAT Database. http://www. eurocat-network.eu/PRENATALSCREENINGAndDIAGNOSIS/PrenatalDetectionRates (data uploaded 27 Oct 2011), (accessed 11 Nov 2011). 3 Kuhse H, Singer P. Should the Baby live? The Problem of Handicapped Infants. Oxford: Oxford University Press, 1985:143. 4 Verhagen E, Sauer P. The groningen protocol-euthanasia in severely Ill newborns. N Engl J Med 2005;10:959–62. 5 Alderson P. Down's Syndrome: cost, quality and the value of life. Soc Sci Med 2001;5:627–38. 6 Tooley M. Abortion and infanticide. Philos Public Aff 1972;1:37–65. 7 Hare RM. Abortion and the golden rule. In: Hare RM, ed. Essays on Bioethics. New York: Oxford University Press, 1993:147–67. 8 Hare RM. A Kantian approach to abortion. In: Hare RM, ed. Essays on Bioethics. New York: Oxford University Press, 1993:168–84. 9 Hare RM. The abnormal child. Moral dilemmas of doctors and parents. In: Hare RM, ed. Essays on Bioethics. New York: Oxford University Press, 1993:185–91. 10 Condon J. Psychological disability in women who relinquish a baby for adoption. Med J Aust 1986;144:117–19. 11 Robinson E. Grief associated with the loss of children to adoption. In: Separation, reunion, reconciliation: Proceedings from The Sixth Australian Conference on Adoption. Stones Corner, Brisbane: Benson J, for Committee of the Conference, 1997:268–93, 278. Giubilini A, et al. J Med Ethics 2013;39:261–263. doi:10.1136/medethics-2011-100411 263 Featured article group.bmj.com on June 25, 2015 Published by http://jme.bmj.com/Downloaded from live? After-birth abortion: why should the baby Alberto Giubilini and Francesca Minerva doi: 10.1136/medethics-2011-100411 2012 2013 39: 261-263 originally published online February 23,J Med Ethics http://jme.bmj.com/content/39/5/261 Updated information and services can be found at: These include: Material Supplementary .DC4.html http://jme.bmj.com/content/suppl/2012/07/27/medethics-2011-100411 .DC3.html http://jme.bmj.com/content/suppl/2012/03/01/medethics-2011-100411 .DC2.html http://jme.bmj.com/content/suppl/2012/03/01/medethics-2011-100411 .DC1.html http://jme.bmj.com/content/suppl/2012/02/28/medethics-2011-100411 Supplementary material can be found at: References #BIBLhttp://jme.bmj.com/content/39/5/261 This article cites 4 articles, 0 of which you can access for free at: service Email alerting box at the top right corner of the online article. Receive free email alerts when new articles cite this article. 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