Most actions have several consequences. One of these may be the consequence intended, but there may be other unintended consequences, good, bad or indifferent. These other consequences are the double effects of an intentional action. The principle of double effect is an attempt to come to terms with the morality of situations where an intentional action aims at a good end, but also has unintended bad consequences.
As a doctrine it goes back to Thomas Aquinas, and it is still used in Roman Catholic moral theology.
The philosopher Elizabeth Anscombe takes the example of someone who attacks me with the intent to murder me. It is obviously morally permissible for me to defend myself by the intentional action of striking back. But supposing my retaliation has the unintended consequence that I kill my attacker. Anscombe argues that I cannot be morally blamed for the death of my attacker since his death is an unintended consequence of defending myself. Additional conditions would need to apply such as that I did not use unnecessary force in my self-defence. Granted these additional conditions, I am morally excused by the principle of double effect.
Consider now a second case. Suppose that I acquire reliable advance knowledge that you intend to kill me. To prevent you doing so, I lie in wait and attack you first. As a result you die. Does the principle of double effect excuse me in this case?
In both cases, I have the intention to save my life and use the same means of striking you. But according to the principle of double effect, I am not morally excused in the second case. The principle allows me to intend a good act (defending myself) which turns out to have a bad consequence (your death). But I am not allowed to intend a bad act (lying in wait to injure or kill you) in order to have a good consequence (preventing injury to myself).
Well, okay, suppose we allow that the application of the double effect principle in these two cases provides intuitively acceptable moral conclusions. Nevertheless, we can easily find other cases where the principle is much less plausible. The philosopher/lawyer HLA Hart provides the following example. A man is trapped in the cabin of a burning lorry and he begs a bystander to shoot him to save him from further agony. The bystander does so. But his action would be condemned by the principle of double effect because the good consequences (saving him from death in agony) are brought about by a bad action (killing an innocent person).
The principle has been used in anti-abortion and euthanasia literature in ways which bring out controversial points. For example, suppose that a pregnant woman is diagnosed with cancer of the womb. Her life can be saved by removal of the womb. There is a good intention – to save the life of the woman – but the double effect is bad – the death of the foetus. The principle allows this.
But suppose, due to obstetric complications, the surgeon can save the woman's life only by removing the foetus and so killing it. This would be condemned by the principle; the good result – saving the mother's life – is brought about by a bad intention – killing the foetus. Many people would struggle to justify different moral assessments in the two cases.
Rather different issues are raised in palliative care. We may expect them to be raised when the Scottish Parliament gets round to discussing the Assisted Suicide Bill.
One of the issues which may be discussed concerns pain relief at the end of life. Some will argue that pain relief may hasten death and therefore the physician intends an earlier death for the patient. But there is an ambiguity intrinsic to the concept of 'hastening' death which gives rise to major problems concerning the causation of death. The idea of hastening death can be taken to imply actually causing death as the outcome, or alternatively it may imply simply allowing death to occur as a result of the illness, but at a slightly earlier time. In the latter case, one can be said either not to prolong life or to allow death to occur earlier.
Whereas causing the patient's death is correctly regarded as 'killing', allowing death to result from the organ failure consequent upon illness is commonly called 'letting die'. The use of these terms has tended to polarise the whole discussion into crude contrasts between killing and letting die. Unfortunately 'hastening death' could be taken to mean either or both.
Allowing death to occur (letting die) has to be permitted when the burdens and risks of life-prolonging treatment clearly outweigh its benefits. At the same time, society needs to maintain its prohibition against killing (murder) in order to protect its members. To achieve these two aims, both the law and professional guidance have to uphold a clear distinction between killing and letting die.
The legal situation is fortunately quite clear. In law, an act of killing is murder if one person intended to cause and did cause the death of another. Thus, if a doctor 'hastened' death by knowingly administering a lethal injection, he/she could be charged with murder. On the other hand, a doctor who withholds or withdraws a life-prolonging treatment from a patient because its burdens and risks outweigh its benefits, or because the patient refuses the treatment, is considered to have allowed a foreseen death to occur from natural causes and is not charged with murder. In this situation, letting the patient die is legally permitted.
In many cases, a problem can be created simply by the way the situation is described. For example, in the palliative care cases, those in favour of changing the law to permit euthanasia have argued that increasing pain relief in a dying patient causes the patient's death, that the physician's intent is to relieve suffering by causing death. This is euthanasia under another description, they claim, so why not make this explicit and legalise it.
Those in palliative care are likely to reply that the intention is to relieve pain; the death of the patient is inevitable from the underlying condition so all they are intending is to create the possibility of as pain-free a death as is possible for the patient, even if this is earlier than it would have been if the pain relief had not been administered. The point here is that there are usually several ways of describing a situation.
Moreover, the idea of what one is 'intending' can be cloudy and ambiguous, especially in difficult circumstances. Are we always aware of what we are intending?
Readers will remember the account of the death of Captain Oates in the Antarctic as reported in Captain Scott's diary. The team were in a desperate situation and Oates had an injury to his leg which required the party to move more slowly than otherwise they would. Oates left the tent and said: 'I am going out. I may be some time'. He was clearly intending to die in the snow.
For those who accept the principle of double effect, this was to act on a morally bad intention – to commit suicide – for a good double effect – to relieve pressure on the remaining group. They could also suggest that Oates had the good intention to walk back to the base camp on his own, with the foreseen double effect that he would fall and die a hundred yards from the tent. This is obviously a ludicrous way to interpret the situation, and would appeal only to those who regard suicide as always wrong. Scott recorded in his diary that they had tried to dissuade him but recognised that this was the act of a brave man. Most of us would concur with Scott's view.
The principle of double effect is used by those who wish to maintain absolute principles: that abortion is always wrong, that suicide is always wrong, and so on. They preserve the absolute nature of the principles by defining the intention so that it is always for a good end.
My own view is that many principles may be relevant in a difficult situation and the way forward is to weigh them up in the light of the known facts and then make an all-things-considered judgement. Avoid absolutes. Mind you, a student of mine who was convinced of the desirability of avoiding absolutes hit a problem. She wanted her marriage vow to be: 'forsaking nearly all others'.
Robin Downie is Emeritus Professor of Moral Philosophy at the University of Glasgow
