The manner of killing
Whether the specific manner of a killing can make a moral difference when all other things are equal is where Finnis and Foot part ways. As Finnis has argued, directly intended killing is prohibited in every scenario, even if it is the only means of preserving the most amount of life. The most obvious example of directly intending fetal death in abortion is, of course, where fetal death is desired in itself as the purpose (or one of the purposes) of the abortion. But what if this were not so? It may be argued that in many abortions, it is not fetal death but an end to the pregnancy which is being aimed at; the death of the fetus is merely the inevitable side-effect of terminating the pregnancy, like the insurance bomber example.
Importantly, Finnis argued that the distinctive feature of directly intended killing has much to do with the causal structure of the act. By his lights, killing the fetus is directly intended if it is used as a means of securing the end of the pregnancy and if that wider purpose cannot be achieved without it. The example he uses is where a craniotomy is performed on a fetus during a partial-birth abortion as a means of extracting it from the woman, killing the fetus by crushing its skull. The same analysis would appear to apply to most methods of abortion, including abortion by vacuum aspiration or dilation and curettage, where the fetus is killed in the process of being extracted. In such abortions, the death of the fetus is inextricably linked to the extraction procedure—killing the fetus is an unavoidable part of the extraction. As Finnis sees it, such abortions are ‘inescapably’ characterized as ‘antilife’, and thus subject to the absolute prohibition on killing.^ Whether or not one wills it as an independent aim, he argues, to choose fetal death as a means to an end is a ‘choice against life’ of the kind that cannot have a results-based justification. Given the personhood proviso, Finnis concludes that:
The traditional condemnation of therapeutic abortion is the straightforward application of the intention/foresight distinction to the case where mother and child are equally persons, and neither is to be directly attacked. 
For Finnis, the absolute prohibition on direct killing simply applies both ways. One cannot fatally attack the woman to save the fetus, and one cannot fatally attack the fetus to save the woman, whether or not the other conditions for the necessity defence are made out. But not all abortions are directly intended killings on Finnis’s definition. This includes the abortion by hysterectomy, where, for instance, a pregnant woman’s cancerous womb is removed in order to save her life, in the knowledge that the non-viable fetus within it will die. The traditional condemnation does not apply here, he explains, since the DDE exception extends theoretically to an abortion where there is logical room to characterize the overriding intention as that of preserving life rather than destroying it. This is true of removing the malignant womb because it involves no attack on the fetus’s body, does not depend for its success on the death of the fetus, and would have been carried out all the same if the fetus were not present. In Finnis’s view, these features mean that removing the womb better resembles unplugging the violinist, where death is foreseen as inevitable but not aimed at directly.
Finnis thus posits a crucial difference between the therapeutic removal of a cancerous womb containing the fetus, and the therapeutic abortion by craniotomy. In contrast to the removal of a malignant womb, the craniotomy abortion cannot but be construed as directly intending fetal death as a means to an end, even if it is not an end in itself (say, because fetal death per se is not wished for, but only an unavoidable consequence of saving the woman). This, it seems, is because the fatal attack on the fetus’s body cannot logically share space with the hope that it will live.
A killing that DDE precludes from being directly intended is still subject to proportionality requirements, and Finnis expressly reminds us of this. Thus, even abortion by hysterectomy is justifiable for nothing less than saving the life of the pregnant woman. But Finnis is convinced that the craniotomy is absolutely prohibited regardless of proportionality. Just as you cannot kill the violinist by having someone chop him into pieces, even to save your own life, so a pregnant woman cannot have her fetus aborted in a manner that aims at its death as a means or an end.
Foot disputed Finnis’s claim that the causal structure of a directly intended killing will absolutely bar its permissibility. ‘If you are permitted to bring about the death of the child’, she asked, ‘what does it matter how it is done’?44 As far as Foot was concerned, the people in the cave will act permissibly if they kill the large man by blowing him up (a direct attack), since he will perish in either case, and only by doing so can they be saved. The difference between direct and indirect intention is not morally relevant, she argued, when killing directly does not cause any more harm to the victim than he will in any event sustain, and is in the interests of saving more life. As she said of the cave scenario:
It is a great objection to those who argue that the direct intention of the death of an innocent person is never justifiable that the edict will apply even in this cased5
Foot applied the same reasoning to the death of the fetus in therapeutic abortion where the fetus cannot be saved. If nothing can be done to save the life of the fetus, the doctrine Finnis espouses will fly in the face of what she said most reasonable people would think. Foot was aligned with Finnis in thinking that extracting the fetus by craniotomy to save the woman is impermissible if the fetus is a person and is not beyond saving anyway; one cannot kill one innocent person to save just one other if the victim would not otherwise die, since the balance of life is equal on both sides, but killing one person is worse than letting another person die. Where Finnis and Foot differ is in Foot’s denial that where an abortion by hysterectomy is permissible (on her view, when neither woman nor fetus would otherwise live), an abortion by craniotomy is not. This denial has an important place in Thomson’s defence of abortion, made more explicit in her own reply to Finnis’s criticism. Thomson argues that for Finnis to be correct, it needs to be shown that the difference between the two kinds of killing is pertinent when everything else is equal. But along with Foot, she cannot bring herself to believe that this is true. The idea that ‘abortifacients taken by a teaspoon’ could sometimes be ‘morally safe’ but that a craniotomy for the same reasons is just ‘far too messy’ to be permissible strikes her as absurd.46
It is clear that on Finnis’s view, even the circumstances in which ‘abortifacients taken by a teaspoon’ could be morally safe would be extremely circumscribed. The medicine would have to be, first and foremost, necessary for curing the woman of a life-threatening ailment, and only destructive to the fetus as a side-effect. It would also have to be the case that she would have taken the medicine even if not for the fetus’s presence in the womb. Thomson’s criticism here should therefore be read as one which rejects the importance of these kinds of features. When abortion meets the conditions for proportionate killing, and the respective prospects of woman and fetus also meet the general conditions for morally permissible killing, the fact that a killing directly aims at a fetus’s death, and that the act which kills wouldn’t be chosen but for its presence, is not prohibitive in effect.
Finnis’s response to this scepticism about the moral difference the manner of a killing can make when all other things are equal directs the inquiry back to the existence of deontological constraints per se. As he reasons, to deny that the directness of a killing has moral import is in a way to eschew deontological constraints on killing altogether, and this is something he believes Foot and Thomson would be loath to do. Clearly, Foot did not believe that the maximization of life is justification enough for any kind of a killing. She did not believe the doctors may cut up the healthy patient to use his organs to save five others, or that a judge may execute an innocent man in order to avoid a bloody riot. But she did think it permissible to blow up the large man to save others trapped in the cave so long as he is certain to die soon anyway. Finnis asks whether this is not ‘an unwarranted though plausible concession to consequentialism’Th The only reason Foot thought it acceptable to kill the man in the cave through direct attack is because it would maximize life saved, without changing the outcome for him. But if this is sufficient justification for directly killing the large man, it would also seem to justify cutting up the patient if he is fated to die imminently of a terminal illness. Finnis has pointed out that Foot’s principle might also justify an agent (D) killing an innocent person (V) when ordered to do so under threat from P, in circumstances when P would otherwise kill V along with D. The fact that neither Foot nor Thomson would countenance ‘moral horrors’ like these, including ‘saving life by killing innocent hostages, etc’, is, for Finnis, testament to their belief that it does matter whether one’s choice aims at death as a means or an end, or just accepts it as an unavoidable side-effect of saving the greatest amount of life.
It is not my ambition here to make the case for the existence of deontological constraints on killing or injuring. No doubt there are many who would object to the notion that there are any actions the nature of which renders them absolutely prohibited regardless of what gains can be made by performing them. But Finnis’s wider point is that moral philosophers who deny the moral difference between direct and indirect intentional killing in the therapeutic abortion of a fetus-person do, nevertheless, accept the operation of side-constraints in other scenarios where the consequentialist position is in fact far more seducing. (We might take, for example, the permissibility of using torture to extract information from a terrorist when we are certain he knows where a bomb is planted.) Finnis’s starting point— that some actions are too set against the value of human life to be performed—is one that Foot and Thomson do seem to share. However, while they regard factors such as the victim’s own imperilment (for Foot) or her imposition on others (for Thomson) as relevant to that characterization, they do not accept the same thing about the causal structure of killing. As Thomson has it, when all else is equal, the distinction between directly and indirectly intended killing is simply too technical to be of consequence. Is she right to believe this?