The Principle of Double Effect

A History and Philosophical Defense

David Černý

• Publisher: Routledge
• Year: 2020
• ISBN:
  9781000061925
• Edition: 1
• Topic: Philosophy
• Subtopic: Ethics & Moral Philosophy

This book offers a comprehensive history of the principle of double effect and its applications in ethics. Written from a non-theological perspective, it makes the case for the centrality of the double effect reasoning in philosophical ethics.

The book is divided into two parts. The first part thoroughly examines the history of double effect reasoning. The author's history spans from Thomas Aquinas's opera omnia to the modern and influential understanding of the principle known as proportionalism. The second part of the book elucidates the principle and addresses various objections that have been raised against it, including those that arise from an in-depth discussion of the trolley problem. Finally, the author examines the role of intentions in ethical thinking and constructs a novel defense of the principle based on fine distinctions between intentions.

The Principle of Double Effect: A History and Philosophical Defense will be of interest to scholars and advanced students working in moral philosophy, the history of ethics, bioethics, medical ethics, and the Catholic moral tradition.

1 Introduction

Human action is not black and white: it can have good and bad consequences, which together give rise to the moral dilemmas of everyday life. A father rushing his ill son to hospital does not observe the prescribed speed and increases the risk that he will run over a pedestrian or cause an accident. A physician considers an operation which will save his patient’s life but kill her unborn child. A dentist, while operating, causes his patient pain. A man decides to visit his friend in hospital, although he knows that he will make his wife angry. Soldiers must bomb the enemy’s ammunition deposit, but they know that innocent civilians will be killed. Life constantly places us in situations when we must consider an action that does not have only good consequences. In the many hundred years of tradition of moral reflection a doctrine has crystalized determining the conditions on which an action that has good and bad consequences can be actualized: we speak of the principle or doctrine of double effect or practical deliberation based on double effect.

According to the principle of double effect an act with good and bad effects can be actualized if certain conditions are met; mostly four are stated:

1. The act itself, regardless of its consequences, is at least morally indifferent (it is morally good or indifferent).
2. Only the good effect is intended, the bad effect must not be intended.
3. The bad effect is not a means of attaining the good effect.
4. There is a grave reason to actualize the act that has both types of effects (good and bad).

The doctrine of double effect originated in the context of Catholic moral theology. It first appeared, at least according to some historians, in the work of the medieval philosopher and theologian Thomas Aquinas. It was further developed by other Catholic authors such as Tommaso de Vio, Francisco de Vitoria, Domingo de Sta Teresa and in the 19th century by the Jesuit moral theologian Jean Pierre Gury in his influential work Compendium theologiae moralis. The principle of double effect received the highest status in the work of Peter Knauer, the founder of a modern strand of moral theology – proportionalism, who made it a hermeneutic principle in the light of which all basic concepts of moral theology are defined and all human action evaluated.

But it would be wrong to believe that the principle of double effect is strictly associated with Catholic moral theology. In the recent decades it has received the attention of authors not adhering to this tradition, whether affiliated to another religious tradition or without religious creed. Most often this moral principle is encountered in the works of modern applied ethicists who discuss its validity and possibilities of application in the context of contemporary ethical discussions.

Let us take a look at just a few examples from contemporary applied ethics.

1. Just War. One of the central moral rules of ius in bello is the principle of civilian immunity, which forbids killing innocent civilians. However, as Steven P. Lee has observed, if this principle were taken literally, we would be morally bound to unconditional pacifism arising from the tension between the following two statements¹:

1. Killing civilians in war is morally totally inadmissible.
2. War cannot be conducted without civilian casualties.

The first statement expresses an important moral norm, which for many is undoubtable, while the other is a realistic evaluation of the possibilities of conducting war: regardless of efforts to avoid civilian casualties there will always be some, and they are even highly probably linked to certain types of attacks, e.g. bombing. The principle of double effect can² provide a way out of this tension. In the context of just-war theories it is often formulated as follows: civilian casualties must not be intended, they must be merely foreseen, and there must be a proportional reason for carrying out a certain kind of military action. The expression “proportional reason” is intended to convey that the planned strategic military outcome of the action must be so important (for example, destabilizing the enemy army’s headquarters) that it outweighs the unintended civilian casualties.

2. Palliative Care. Palliative care strives to accompany (not only) dying patients on their path through their disease, to alleviate their pain and other symptoms, to improve their psychological and mental state, and to ease their existential or spiritual anxiety. In the context of modern palliative care the double effect principle is most commonly mentioned in connection with administering opioids at the end of life when they can affect the patient’s respiratory drive and thus have the potential to shorten her life. When the palliator in alleviating serious pain or other symptoms with which the patient finds it difficult to cope (i) intends to alleviate the pain or other symptoms (ii) in order to improve the patient’s quality of life or facilitate an easier death for her, (iii) alleviating the pain or other symptoms is the action’s intended effect, (iv) accelerating the process of dying is an unintended negative consequence of the physician’s action, (v) there is a proportional reason to actualize the action regardless of the negative consequence associated with it.³ Today many authors are stressing that the fear regarding opioids is unjustified as, correctly administered, opioids do not make life shorter; quite the contrary – they prolong it. But the reasoning structure laid out above in connection with end-of-life measures can also be applied to more complex situations. For example, some patients are highly agitated towards the ends of their lives and calm down when they are administered a drug such as Diazepam. But a consequence of that is that they are sleepy, do not drink enough, do not move sufficiently and thus run a higher risk of developing pneumonia. In other cases some patients are assisted in breathing by a centesis in the abdomen, but draining several litres of fluids in ill patients can result in shock and death. In all these cases the principle of double effect can be applied.⁴

3. Roboethics. Different versions of the trolley problem have played an important role in roboethics, a modern branch of applied ethics. They appear, for example, in discussions of the ethical rules that ought to govern autonomous vehicles in case of imminent collisions. Some authors hold that the principle of double effect (possibly together with the principle of triple effect) can systematically explain the various moral intuitions evoked by the numerous versions of this problem’s traditional formulation. It is even fairly easy to model moral decision-making that conforms to the principle of double effect by means of prospective logical programming in the ACORDA⁵ language. Thus, the principle of double effect could also play an important role beyond the context of trolley problems: for example in ethically regulating the behaviour of medical, nursing, caring, rescuing or military robots.

But the principle of double effect remains a controversial principle: there is no agreement whether the principle is valid (its validity is rejected mostly by authors adhering to the consequentialist tradition) and there is even no agreement as to what form it should in fact take. In contemporary bioethical literature two claims most commonly appear: (i) the principle of double effect takes the form I have stated above and (ii) the history of the principle of double effect begins among authors belonging to the famous school in the Spanish Salamanca. In other words, it is assumed that there is precisely one principle of double effect (perhaps in different formulations), which first appears in the works of philosophers and theologians of the Salamanca school.

In my work I would like to dispute both claims and defend the following three theses:

1. It is impossible to speak of one principle of double effect. In history we encounter various formulations, which are not merely different expressions of the same principle. All formulations are set in a certain ethical context, in which they can play and often do play a different role. To speak of “the principle of double effect” is, from the historical point of view, inadequate.
2. The first formulation of deliberation based on a principle of double effect – on weighing the moral permissibility of actualizing an action that has good and bad consequences – appears in the work of the Dominican philosopher and theologian Thomas Aquinas.
3. The principle of double effect in the form I give it in the last chapter of my work remains a controversial moral principle, where its presuppositions (especially ethics taking into account the intentions of actors in ethical evaluation of their acts) are especially controversial. When these presuppositions are accepted, the principle of double effect appears to be a rational way of justifying a certain act.

In the second chapter, titled A Brief History of the Principle: Thomas Aquinas, I focus on the medieval philosopher and theologian Thomas Aquinas. In the Secunda Secundae of his Summa Theologiae Doctor Angelicus, as he is called, discusses the admissibility of killing the aggressor in an act of self-defence in the context of discussing commutative justice. Here Thomas explicitly says that one human act can have two consequences: (i) one is good (saving one’s life), and (ii) the other is bad (aggressor’s death). The moral evaluation of self-defence is set in the broader framework of Thomas’s perfectionist conception of morality and starts from the premise that maintaining own life is natural to every being. If killing the aggressor is not included in the agent’s intention (according to Aquinas’s terminology praeter intentionem) and is further appropriate to the act’s end (self-defence), it is not impermissible from the moral point of view. In the same chapter he further gives a detailed account of the theory of fontes moralitatis (moral evaluation of human action is determined by three sources: object, end and circumstances) and distinguishes between human action in genere moris and in genere naturae.

But not all authors have regarded Thomas’s treatise as the first formulation of a certain version of the principle of double effect. Interpretative disputes have focussed on the meaning of the phrases in intentione and praeter intentionem and also per accidens and quandoque. That is why I analyze the individual interpretations, in turn – ones penned by Joseph T. Mangan, the first historian of the principle of double effect, Leonard Lessius, author of the 17th-century treatise De iustitia et iure, Steven A. Long, T. A. Cavanaugh, Gareth B. Matthews and Joseph Boyle. My analyses result in the claim that Thomas Aquinas in fact presents his version of the principle of double effect, which is, however, an application of already existing principles of moral evaluation of human action to the particular example of self-defence. Thomas’s version of the principle of double effect therefore plays a fairly marginal role in his thought. But I have succeeded in defending the first thesis of my work: Thomas Aquinas is the founding father of the ethical tradition employing the principle of double effect.

In the third chapter, called A Brief History of the Principle: Cajetan to J. P. Gury, I attempt to remove some deficiencies of historical overviews of the development of the principle of double effect. Although these overviews mention all the important authors, they do so often very briefly and do not provide the reader with the original Latin texts and their interpretation. For this reason I have selected the authors I regard as most important – Tommaso de Vio, called Cajetan, Francisco de Vitoria, Domingo de Sta Teresa and Jean Pierre Gury – and the key passages of their works, which I have translated. I analyze the selected texts in detail, comment on them and structure their arguments and formulations of the principle of double effect as intelligibly as possible, to some extent formally. I leave the question whether all the authors mentioned presented the same version of the principle of double effect open until the conclusion of the following chapter.

In the 20th century the climate among Catholic moral theologians changed and they began to raise questions that were impermissible for the preceding moral tradition. These theologians increasingly emphasized the importance of moral description of human action, which was in their view quite inadequately determined only in terms of its physical description. A growing number of experts in moral theology also disputed the infallibility of the moral teaching of the Catholic Church, expressed e.g. in Pope Paul VI’s controversial encyclical Humanae vitae, especially in connection with means of artificial birth control (contraception). These events prepared the ground for a new direction in moral theology, which obtained the name proportionalism and spread especially in the United States of America. But the (perhaps inadvertent) founder of proportionalism was the young German Jesuit theologian Peter Knauer.

The fourth chapter focusses primarily on two spheres: (i) presenting the hermeneutic function of the principle of double effect according to Peter Knauer and (ii) comparing his conception and formulation of the principle of double effect with those from the preceding chapters. With Peter Knauer I focus on his new formulation of the principle of double effect and the role it plays in his entire moral system. This principle speaks not only on a limited number of acts but also on the whole of morality. In light of the principle of double effect Knauer tries to define all the basic concepts of morality, such as the concept of bad and good action. I show how in distinguishing between psychological and moral intentions the author redefines the concept of intention and how he construes the concept of moral causality. In the concluding part of the section devoted to Knauer I try to illustrate his somewhat vaguely defined concept of proportional reason, to which the principle of double effect itself and thereby in fact all of morality is ultimately reduced.

In a further section of the fourth chapter I prove my second thesis: I summarize the individual formulation of the principle of double effect and demonstrate that they are set in different ethical systems in which they often play very different roles. In the concluding part of the chapter I briefly deal with the proportionalism of the American theologian G. L. Hallett and show how in his work the principle of double effect was transformed into a criterion of value maximization.

In the fifth chapter I direct attention to four important authors: the British theorist and philosopher of law Herbert L. A. Hart, the British moral philosopher Philippa Foot, her American colleague Judith J. Thomson and Francis Kamm. I lay out Hart’s theory of intentions and its application in criminal law, but I specially focus on the author’s criticism of moral asymmetry between hysterectomy and craniotomy. Advocates of the principle of double effect usually regard hysterectomy as licit, but they reject the possibility of craniotomy, since the physician’s intention in this medical procedure is killing the foetus (crushing its head). Hart, on the other hand, claims that the physician’s intention need not be to kill the foetus: the physician may intend crushing the foetus’s head without the object of his inte...

Table of contents

• Cover
• Half Title
• Series Page
• Title Page
• Copyright Page
• Dedication
• Table of Contents
• Acknowledgments
• Foreword
• 1 Introduction
• 2 A Brief History of the Principle: Thomas Aquinas
• 3 A Brief History of the Principle: Cajetan to J. P. Gury
• 4 Peter Knauer and Proportionalism
• 5 The Principle of Double Effect and Trolleyology
• 6 Defence of the Principle of Double Effect
• 7 Conclusion
• Literature
• Index