The ‘slippery slope’ argument in the context of euthanasia

1. Introduction

Euthanasia (εὐθανασία 1) is arguably the most topical and widely debated issue in bioethics, one which concerns not only specialists in the scientific field but also society at large. There are many reasons for this. Firstly, [euthanasia]2 is, by its very nature, a matter of life and death, since it concerns a decision regarding the termination of a person’s life. Secondly, the fundamental moral issue does not require specialist knowledge, nor an understanding of complex medical procedures or applications of genetics. All people have, to some extent, experienced illness and physical pain and, at the same time, understand the fundamental moral dilemma between upholding the sanctity of life and the autonomous decision to end it. And, thirdly, the issue of euthanasia potentially concerns every person, both personally and through their loved ones, as the end of life is, at some point, inevitable for everyone. As scientific progress makes it possible to prolong life, there is an increasing number of cases in which decisions must be made regarding the medical approach to terminally ill patients 3. Thus, the debate on euthanasia is not simply about resolving a medical issue for a particular group of patients, but takes on a personal dimension, as it relates to the existential anguish faced in the face of the end of life and death.

The issue of euthanasia arises at a time when, on the one hand, human life enjoys the greatest respect and protection in history, and, on the other hand, great value is placed on self-determination (αὐτοπροσδιορισμός), freedom of will and individual rights. Consequently, this is a controversial issue that appears to divide contemporary society. As is to be expected, arguments based on ethical principles and values are put forward both in favour of and against the moral acceptance of euthanasia. In support of accepting euthanasia, the principle of autonomy and the virtue of compassion towards a suffering neighbour are invoked, amongst other things, whilst its rejection [is based on] the sanctity of life, the prohibition against killing one’s fellow human beings, and the medical ethos of treatment and pain relief.

In this study, we shall present and evaluate another type of argument, one that is frequently invoked in the context of euthanasia, namely that of the ‘slippery slope (ὀλισθηρός δρόμος4)’, which is used to reject euthanasia. Unlike the arguments mentioned above, which are based on ethical theories as well as on ethical principles and values, with a primarily deontological content, the ‘slippery slope’ argument is an eminently teleological and consequentialist (τελεολογικό καί συνεπειοκρατικό 5 ἐπιχείρημα). It does not base its probative force on a widely accepted ethical principle, such as respect for human life and personal autonomy, but on the consequences of the act under consideration. If, for example, what is good is judged by Christian morality on the basis of its agreement or disagreement with the word and will of God [whereas,] according to a consequentialist argument, it is judged on the basis of the outcome. Considering the outcome as the determining factor creates an unstable foundation for building a sound argument, as outcomes may vary depending on the era and on each society. At the same time, however, it creates an argument that is easy to understand and extremely influential, as all people perceive and desire favourable outcomes. And whilst an ethical principle may be subject to different interpretations and ways of perceiving it, outcomes are, as a rule, concrete, measurable and fully intelligible. Thus, a consequentialist argument, such as the ‘slippery slope’ argument, even though it is not usually regarded by bioethicists as one of the most important arguments concerning the moral consideration of euthanasia, exerts a great influence on society. We shall therefore now present this argument, examine how it is formulated and applied in relation to the rejection of euthanasia, and conclude our discussion with a series of conclusions regarding its probative value and its use in contemporary bioethical dialogue.

2. Presentation of the argument

According to this argument, an action to be assessed from a moral point of view is first considered acceptable; its foreseeable consequences are then examined so that, ultimately, one may conclude that the initial acceptance of the action proves, depending on the results, to be either correct or incorrect. Although, in theory, the slippery slope argument can be used to either accept or reject an action, in almost all cases it is used to reject an action on ethical grounds. For this reason, even though other terms have been used to denote the importance of the secondary consequences of an action for its moral evaluation, the term ‘slippery slope argument’ (the ‘slippery slope argument’), whilst in German-speaking literature the term ‘Dammbruchargument’ (the ‘dam-burst argument’)6 has been adopted – two particularly evocative terms that clearly indicate the negative consequences of an action 7. The first term conjures up the image of a slippery slope, on which there is a high risk of losing one’s footing and causing serious damage, whilst the second term evokes the image of water surging forth uncontrollably after a dam bursts, destroying everything in its path. Once someone slips or the dam collapses, all possibility of control is lost, and the destructive consequences that will inevitably follow can no longer be stopped.

These images evocatively convey the central idea of this argument, namely that the eventual acceptance of an action under consideration will, inevitably or with a high degree of probability, lead to significant negative consequences that cannot subsequently be stopped or counteracted. Consequently, in order to avoid these consequences, it is necessary that no one should accept the action under consideration, even if it is considered, in itself, to be morally acceptable. The slippery slope argument must not be confused with the mere expression of fears and concerns about the future, as it sets out, in a reasoned manner, the anticipated negative consequences. The structure of the argument can be summarised as follows:

1) Let us assume that an action A is morally acceptable 8.

2) Accepting action A inevitably, or with a high degree of probability, leads to action B, which in turn leads to action C, and so on.

3) Since actions B and C have significant negative consequences and are considered morally unacceptable, it follows that one ought to morally reject action A as well 9.

The slippery slope argument is widely used in bioethics, as moral deliberation concerns, amongst other things, the consequences of the new possibilities arising from the spectacular progress of medicine and, more generally, of biotechnology 10. Those scientists who attach great importance to these issues tend to view this argument favourably. It is worth noting that Tom Beauchamp 11 and James Childress [† 2023] 12, two prominent bioethicists and proponents of the well-known four principles of bioethics 13, although they consider that euthanasia is morally justifiable under certain conditions, ultimately reject it, taking into account the negative consequences that are expected to follow 14. Others, however, consider that the slippery slope argument does not contribute significantly to the moral debate, as it demagogically fosters fear of any progress in science and technology. It is, therefore, a highly controversial argument, which we shall evaluate as we go on to examine how it is formulated in the context of euthanasia.

3. The use of the [slippery slope] argument to reject euthanasia

We shall begin with a characteristic example of the use of the [slippery slope] argument by the late Archbishop of Athens, Christodoulos [1998–2008], regarding the rejection of euthanasia. Let us imagine, he writes, a future society in which the natural law—according to which no one has the right to kill their neighbour—will no longer apply, but instead the view will prevail that it is right for someone to die with dignity. He continues: ‘For a very elderly person or someone with a terminal illness, there will be an initial stage, consisting of a request for euthanasia made by the person themselves or by their relatives. The request will be examined by doctors and, following a brief procedure, the appropriate authorisation will be granted. This will be followed by a second stage, which will involve the imposition by law of euthanasia in certain cases, regardless of the patient’s wishes, for economic reasons and to provide care for other patients who, in the doctors’ opinion, have a chance of recovery… Consequently, in line with the so-called ‘pragmatic approach’ to cost-saving – the non-involvement of younger relatives and the reduction of healthcare costs – it is possible, as I see it, lead to a nightmarish society in which citizens over the age of 90, for example, will be required to undergo an ‘objective assessment’ of their state of health, and if this assessment shows that they must be killed, ‘so that their end may be dignified’, they will be sent to luxurious, purpose-built crematoria…”15. The late Archbishop describes the prospect of such a society as a nightmare and, for this reason, concludes that we must remain steadfast in our respect for life and reject euthanasia.

Let us, however, examine more systematically the negative consequences invoked, which, according to the argument under consideration, always necessitate the categorical rejection of euthanasia. Typically, proponents of this argument cite the following four consequences:

a) The acceptance of involuntary euthanasia. Although euthanasia is presented by its supporters as an act of freedom and an expression of human dignity, its eventual acceptance will inevitably lead to the acceptance of involuntary euthanasia, which even many of the supporters [of euthanasia] categorically reject. When someone grants a patient’s request to die with dignity in order to be freed from suffering, on the grounds that they consider it morally just to kill that person, then it is to be expected that they will also proceed to kill another patient who is in exactly the same situation, but who is unable to express their wish 16. James Keown 17 explains the inevitability of the slippery slope from accepting voluntary euthanasia to accepting coercive euthanasia through the following reasoning: the moral justification for euthanasia is based on two premises, namely the patient’s free will and the consent of the responsible doctor. The second premise is considered absolutely necessary to prevent abuse of requests for euthanasia in cases where the illness is curable, the pain is temporary and treatable, and the patient’s living conditions are dignified. Since all of the above fall within the doctor’s remit, and also because he will be called upon to carry out the euthanasia, his role is decisive; for only if he gives his consent will euthanasia be carried out. However, when the doctor decides competently and in accordance with their duty whether there are grounds for ending the patient’s life, then, inevitably, the existence of a request from the patient becomes of secondary importance, especially where the patient is unable to express their will 18.

Moreover, the free expression of the patient’s will, the credibility of the request for euthanasia and the perception of a loss of dignity are not objective in nature and are not universally accepted; rather, they are subject to subjective interpretation and, consequently, to potential abuse on the part of the doctor 19. Consequently, it is to be expected that the doctor will end up applying what he himself considers to be correct or what is imposed on him by the directives of governments or the competent health authority, which will determine, for example, the omission of certain surgical procedures or other costly forms of treatment for specific cases of illness 20.

b) Pressure on the patient to request euthanasia. Although euthanasia is presented by its advocates as an additional option for the patient, one that expands their freedom, the very possibility of choosing to end their life immediately is likely to place them under great psychological pressure to choose what appears to be in everyone’s best interests: to free themselves from pain, to relieve their relatives of the burden of caring for them, to relieve the healthcare system of the high costs of their hospitalisation, and to free up a bed in the hospital. When the doctor informs the patient of the possibility of choosing to end their own life, it is as though they are indirectly encouraging them towards this choice 21, as many patients feel they have become a burden to their loved ones, who are financially strained and exhausted by caring for them, and that they have a moral duty to relieve them of this burden 22. It goes without saying that one must take into account the fact that psychological pressure from society will also be strong, given that economic resources are limited and there are many people in need of medical care 23. Any decision to refuse euthanasia is likely to be seen as selfish and anti-social.

Consequently, although euthanasia is currently presented by its supporters as an additional option and a last resort to relieve the terminally ill patient of unbearable suffering, legalising it it becomes an easy way out of an unpleasant situation, rendering the search for other approaches pointless.

c) The undermining of the doctor-patient relationship. Euthanasia is contrary to medical ethics, as a doctor’s role is not to kill the patient but, on the contrary, to treat them and alleviate their pain 24. However, when the possibility of euthanasia arises, the doctor’s position vis-à-vis the patient and their relatives becomes particularly difficult, as they are called upon to decide whether and when it is right to respond to a request for euthanasia, a request which is often made in moments of pain and despair, and may therefore not reflect the patient’s true wishes.

As has been emphasised, the doctor’s responsibility to decide on the life of a fellow human being runs counter to their professional vocation and undermines the patient’s trust, regardless of the final decision they make. If the doctor agrees to the request for euthanasia, they abandon efforts to cure the patient and alleviate their pain, a fact which raises the question of whether this decision was made too hastily, given that there is no possibility of reversing it. If, on the other hand, he or she rejects the request for euthanasia, then he or she assumes personal responsibility for the continuation of life and, with it, of another person’s suffering 25. In both cases, there will always be doubts regarding the motives and correctness of his decision, thereby seriously undermining trust in the doctor as a person – trust which is essential for the successful practice of medical care.

At least since the time of the Oath attributed to Hippocrates, the importance of the relationship of trust between doctor and patient has been recognised, and medical confidentiality (τό ἰατρικό ἀπόρρητο), which is defined in the Oath, underpins that relationship. This confidentiality has not been called into question, not even when the issue of informing the partners of patients with AIDS was raised, precisely so as not to undermine that trust. As some advocates of euthanasia, such as the well-known Peter Singer 26, acknowledge, once euthanasia is legalised, it is possible that many elderly patients may view the administration of medication by their doctor with suspicion and fear 27.

d) The weakening of the prohibition [on killing]. The prohibition on killing enshrines the fundamental human right to life and affirms society’s firm will and determination to protect the life of each of its members. The importance of the prohibition against killing therefore also has a social dimension. Indeed, when the value of human life is underestimated and becomes subject to the decisions of others, it is not only a particular category of people that is at risk, but peace and social cohesion itself. Regarding euthanasia as an exception to the prohibition on killing sets a negative precedent, which can easily be used to justify further exceptions 28.

In this way, we slide towards further violations of human life, as every exception to the rule prohibiting the taking of life constitutes an argument for accepting a new exception. For example, denying the unborn child’s right to life by legalising abortion provides an argument for accepting embryo research [and] pre-implantation diagnosis (προεμφυτευτική διάγνωση)[, as well as] for dispelling moral scruples regarding the creation of ‘surplus embryos (πλεονάζοντα ἔμβρυα)’29 in the context of in vitro fertilisation 30. On the contrary, the firm and consistent defence of the prohibition on killing promotes love and solidarity amongst people, protects the most vulnerable and strengthens social cohesion. When society rejects the death penalty, even for the most dangerous criminals, out of respect for the value of life, it seems inconsistent to accept a form of killing which, ironically, is carried out by doctors – that is, by those who are dedicated to the service of life.

Although the above examination of the foreseeable negative consequences that would result from the possible acceptance and legalisation of euthanasia was, in part, evaluative in nature, in that these consequences were presented as plausible, we shall now move on to a more general assessment of the ‘slippery slope’ argument in the context of euthanasia, based on two critical observations that are put forward.

According to the first observation, the ‘slippery slope’ argument appears convincing because it is based on fear and uncertainty in the face of the new, calling for the early prevention of negative consequences which, although possible, are not, however, inevitable or unavoidable in the future 31. Indeed, the exaggeration of possible future dangers constitutes an obstacle to any progress in science and technology, as well as to any change, since anything new may also have negative consequences. To use a characteristic expression that sums up this criticism, life itself is a slippery slope, which we traverse as we move forward, whilst striving to avoid the dangers of slipping on it 32.

In our view, the above criticism is not directed against the argument itself, but against its misuse. Of course, it is not right for someone to reject any innovation out of hand simply by invoking possible future dangers; thus, an argument with such characteristics is not truly sound. The persuasiveness of the slippery slope argument depends on the logical or empirical justification of the predicted consequences, on the estimated probability of their occurrence, and on the extent to which they are considered undesirable. The more convincingly the inevitability of the consequences is presented, and the more negative they are, the stronger the argument becomes.

According to the second observation, the slippery slope argument has an inherent weakness, as it relies on the transition from action A to actions B and C, which subsequently prove to be particularly negative consequences. However plausible one might accept the transition from action A to actions B and C to be, this transition must not be regarded as inevitable or obligatory, since human beings have the capacity to distinguish between them without confusing them and without necessarily sliding towards actions B and C 33. In the same context, the Latin dictum ‘abusus non tollit usum’34 is invoked, meaning that abuse does not negate the possibility of proper use 35. Applying this argument to the alleged slide from voluntary to involuntary euthanasia, it is argued that the supposed slide is not inevitable, as there is a fundamental difference that precludes any confusion between the two, namely the patient’s free will.

This criticism is, in our view, convincing at a theoretical level. Indeed, it is possible that society may remain content with accepting voluntary euthanasia and never slide towards involuntary euthanasia; therefore, the transition from action A to action B is not theoretically inevitable. However, as we have already emphasised, [this transition] is plausible and highly probable, and this fact cannot be ignored in the ethical assessment. The acceptance of voluntary euthanasia will, moreover, create a new reality, in which society will have broken down even the taboo surrounding the killing of a patient by a doctor, and it will already have been established that the value of life is not the highest good, nor does it always deserve protection. In such a reality, whilst it may not be absolutely necessary from a theoretical point of view, it would be logical to expect that society will, at some point, also accept the presumed consent of a patient who is unable to express themselves, and, in doing so, to move towards the acceptance of voluntary euthanasia, on the grounds that this patient, too, should not be deprived of the possibility of euthanasia—a possibility which, we recall, has already been regarded as a moral choice for the healthcare system, as well as for the doctor and the patient.

4. Conclusions

Summarising what we have analysed in our discussion of the subject, we can observe the following:

1) Unlike many other ethical arguments, which are based on concepts that are difficult to understand and on subtle distinctions, the slippery slope argument is an easily understood argument, based on a description of the foreseeable consequences of accepting a course of action, which explains the significant influence it exerts on a large section of public opinion. This argument is widely used in the context of euthanasia, as it is necessary, amongst other things, to assess the foreseeable consequences of its potential acceptance and legalisation. However, for such an argument to be sound, it is necessary, on the one hand, for the assessment of the probable consequences to be well-founded and, on the other hand, for [those] consequences to be regarded by general consensus as particularly negative.

2) However, even when the above conditions are met, the slippery slope argument must be treated as a complementary argument, which enriches the moral discourse, and not as an argument which, in itself, is sufficient for an ethical approach. The main reason is that the evaluation of an action in itself takes precedence, followed by an assessment of its consequences. In particular, for Christian morality, the evaluation of bioethical issues is based on the Church’s teaching regarding the origin, value, nature, purpose and meaning of human life, on marriage and procreation, on love for one’s neighbour, on the significance of pain and suffering, and on eternal life. However, highlighting the expected consequences when these are considered to be contrary to the Christian ethos and particularly harmful to society constitutes an important element of moral reflection.

3) Treating this argument as a complementary one, which enriches moral reasoning, also mitigates the criticism levelled against it. Although it is correctly noted that a slide towards negative consequences is not necessarily inevitable, as it depends on human free will, a well-reasoned presentation of the foreseeable consequences as being highly probable allows for the formulation of a sound argument, which must be taken into account in moral deliberation. Moreover, the argument retains its value even when it does not lead to the rejection of the action under consideration, since merely highlighting the possible negative consequences constitutes a significant contribution to the ethical assessment, as it allows for timely measures to be taken to prevent them.

Translated from the Greek and English, with annotations, by Ion-Marian Croitoru.

• 1

  A Greek term, composed of two words, ‘εὖ (good)’ and ‘θάνατος (death)’, which has not only ethical and philosophical significance, but also bioethical significance (translator’s note).

• 2

  In order to clarify certain meanings or highlight certain nuances, with a view to facilitating a better understanding of the text, I have added some comments, placed in square brackets, with the author’s consent (translator’s note).

• 3

  Or ‘before physical death’ (translator’s note).

• 4

  Or the slippery road, if we consider the literal meaning of the Greek expression used (translator’s note).

• 5

  The term derives from the noun ‘συνεπειοκρατία’, referring to the ethical doctrine according to which the morality of an action is determined by its consequences (translator’s note).

• 6

  Under the influence of the English term, the term ‘Argument der schiefen Ebene’ is also used [with the same meaning].

• 7

  Two other terms that have also been used to describe this argument are the ‘domino theory’ and the ‘tip of the iceberg’. The former expresses the idea that an initial action can trigger a series of chain reactions, whilst the latter that an initial action may contain a dynamic which is not, however, visible from the outset, but which will manifest itself later. These terms have not, ultimately, become established in the specialist literature, although they allow the argument to be used both to support and to reject a course of action. This is due, in our view, to the almost exclusive use of the argument for the purpose of highlighting imminent risks and rejecting a course of action, a fact which favours the choice of terms that evocatively express this purpose.

• 8

  Or ethical (translator’s note).

• 9

  Hugo Lafollete, ‘Living on a Slippery Slope’, in The Journal of Ethics 9 (2005), pp. 477–478; Christian Netzer, ‘Does Pre-implantation Genetic Diagnosis Lead Us Down a Slippery Slope?’, in Ethik in der Medizin 10 (1998), pp. 139–140.

• 10

  David Lamb, Down the Slippery Slope, Arguing in Applied Ethics, London, 2003, p. vii.

• 11

  An American philosopher specialising in ethics and bioethics, a researcher at the Kennedy Institute of Ethics (Georgetown University), known for his contributions to biomedical ethics, research ethics and applied moral theory (translator’s note).

• 12

  An American philosopher and professor emeritus at the University of Virginia, specialising in medical ethics, public ethics and the relationship between morality, religion and health policy (translator’s note).

• 13

  In their classic work, Principles of Biomedical Ethics (first published in 1979), the two authors set out the four principles that are regarded as the foundation of modern bioethics: 1) autonomy, that is, respect for a person’s right to make free and informed decisions regarding their own life and body, which, in practice, means informed consent, respect for the patient’s wishes, the right to choose or refuse treatment, etc.; 2) beneficence, in the sense of acting in the patient’s best interests, with a view to alleviating suffering and restoring health; 3) non-maleficence, in other words, the principle of doing no harm; 3) equity, fairness or justice; in other words, equal treatment for all patients and the fair allocation of medical resources (translator’s note).

• 14

  Tom L. Beauchamp, James F. Childress, Principles of Biomedical Ethics, New York & Oxford, 1994, p. 228 et seq.; John Keown, Euthanasia, Ethics, and Public Policy. An Argument against Legalisation, Cambridge, 2002, pp. 70–80.

• 15

  Christodoulos Paraskevaidis (Archbishop of Athens and All Greece), ‘Christian Reflections on Euthanasia’, in ‘Do Not Quench the Spirit’. Sermons by the Archbishop of Athens on Contemporary Issues, Athens, 2003, pp. 383–385.

• 16

  Nat Hentoff, ‘The Slippery Slope of Euthanasia’, in Jonathan Moreno (ed.), Arguing Euthanasia, New York, 1995, pp. 110–112; Hans Rotter, Die Würde des Lebens. Fragen zur medizinischen Ethik, Innsbruck & Vienna, 1987, pp. 116–117.

• 17

  A contemporary British bioethicist and lawyer (translator’s note).

• 18

  John Keown, Euthanasia, Ethics, and Public Policy, p. 77 et seq.

• 19

  David Lamb, Down the Slippery Slope, p. 3.

• 20

  See John Harris, Der Wert des Lebens. Eine Einführung in die medizinische Ethik, Berlin, 1995, pp. 132–133 (original title: *The Value of Life. An Introduction to Medical Ethics, London, 1985). The British philosopher considers that the real issue with euthanasia is not voluntary euthanasia, which, incidentally, he accepts, but rather coercive euthanasia, which is systematically promoted by various health authorities, who have even provided concrete examples of instructions to hospitals, as reported in the British press. This reference of his, however, seems to reinforce the ‘slippery slope’ argument against euthanasia.

• 21

  Johannes Gründel, ‘Euthanasia out of compassion? Ethical and theological questions’, in Walter Gose et al. (eds.), Active Euthanasia? On the Patient’s Self-Determination, Trier, 1997, pp. 110–112 and 116; see also Eberhard Schockenhoff, Euthanasia and Human Dignity: Accompanying a ‘Self-Determined Death’, Regensburg, 1991, p. 102.

• 22

  Bernhard Häring, Heilender Dienst: Ethical Problems in Modern Medicine, Mainz, 1972, pp. 131–132; Hans Rotter, The Dignity of Life, p. 115.

• 23

  “There are limited resources available for saving lives, and if the cost of keeping a person alive is too high, then a greater number of lives can be saved by redirecting those resources either to other patients or to medical research” [Michael Tooley, ‘Decisions to Terminate Life and the Concept of a Person’, in John Ladd (ed.), Ethical Issues Relating to Life and Death, New York, 1979, p. 73].

• 24

  Bernhard Häring, Heilender Dienst, p. 131.

• 25

  Eberhard Schockenhoff, Euthanasia and Human Dignity, pp. 101–102; see also Dirk Bakker, ‘Active Euthanasia: Is Mercy Killing the Killing of Mercy?’, in Robert I. Misbin (ed.), Euthanasia: the good of the patient, the good of society, Maryland, 1992, p. 91.

• 26

  An Australian philosopher, an advocate of contemporary utilitarianism and, in the field of bioethics, of voluntary euthanasia, as well as of the right of competent individuals to make decisions about their own lives (translator’s note).

• 27

  The Australian philosopher Peter Singer, an advocate of [voluntary] euthanasia as well as of contemporary utilitarianism, observes that such fears are irrational and unjustified, but admits that it is difficult to convince older people of this (ibid., Praktische Ethik, Stuttgart, 1991, p. 246).

• 28

  “Once respect for human life has fallen so low that an innocent person can be killed outright, even at their own request, compulsory euthanasia will inevitably be just around the corner. This could easily lead to the killing of all destitute, incurable patients, elderly people in public care, wounded soldiers, captured enemy soldiers, all children with birth defects, people with mental illnesses, and so on. It will not be long before the danger reaches every citizen’s doorstep” (Joseph V. Sullivan, ‘The Immorality of Euthanasia’, in Marvin Kohl (ed.), Beneficent Euthanasia, Buffalo & New York, 1975, p. 24).

• 29

  The term ‘surplus embryos’ is the one that has come to be used in international literature to refer to embryos produced through in vitro fertilisation but which are ultimately not implanted into a woman’s womb. This term is derogatory towards human beings, as it reduces them to the status of a means to an end, which may be surplus to requirements or insufficient in relation to their needs. For more on this term and, more generally, on the importance of terminology in bioethics, see Miltiadis Vantsou, ‘The Importance of Terminology in Bioethics’, in Scientific Yearbook of the School of Theology, Aristotle University of Thessaloniki / Department of Pastoral and Social Theology, 9 (2004), pp. 147–160.

• 30

  With regard to the prohibition on killing, Christian Netzer points out that it is illogical to permit the abortion of an embryo several months old following pre-natal testing whilst, at the same time, the destruction of an embryo only a few days old following pre-implantation genetic diagnosis (ibid., Führt uns die Präimplantationsdiagnostik, p. 142).

• 31

  Peter Singer, Practical Ethics, Cambridge, 1993, p. 77; Christian Netzer, Führt uns die Präimplantationsdiagnostik, p. 140.

• 32

  Hugo Lafollete, Living on a Slippery Slope, pp. 498–499.

• 33

  Marvin Kohl, The Morality of Killing, London, 1974, pp. 19–20; David Enoch, ‘Once You Start Using Slippery Slope Arguments, You’re on a Very Slippery Slope’, in Oxford Journal of Legal Studies, 21 (2001), pp. 630–631.

• 34

  The literal translation is: ‘abuse does not negate (legitimate) use’, that is to say, as also stated in the explanation provided by the author of the study, the meaning of this maxim is that the abusive use of a thing does not nullify its proper use, or, in other words, the legitimacy of proper use (translator’s note).

• 35

  Josef Schuster, ‘Euthanasia’, in Lexikon der Bioethik, vol. 3, Gütersloh, 1998, p. 454.