My quick answer is that I don't think the doctrine of double effect is inconsistent, whether this means that its formulation involves an inconsistency or that there are inconsistent results when the doctrine is applied to different cases. The concession I do make is that 'The fact that a harm was brought about as a merely foreseen side effect of pursuing a good end does not, all by itself, show that it was brought about permissibly' (McIntyre below).
We need to get clear what the doctrine of double effect exactly is. The following is a useful first step:
Doctrine of double effect
The doctrine of double effect (DDE) Alison Hills, ‘Defending Double Effect’, Philosophical Studies: An International Journal for Philosophy in the Analytic Tradition, Vol. 116, No. 2 (Nov., 2003), pp. 133-152draws a moral distinction between harm that is intended and harm that is merely foreseen and not intended. According to DDE, it is morally worse for an agent to bring about some intended bad consequence than to bring about that consequence when it is merely foreseen, provided that the agent's intention is good, that she does not want or intend that the bad consequence occur and that the foreseen harm she brings about is proportionate to the intended good. For example, many people think that terror bombing, in which the bomber intends to kill civilians, is morally worse than strategic bombing, in which the bomber intends to destroy buildings but foresees killing civilians, even if each bomber does the same amount of damage and kills or injures the same number of people. (: 133.)
The trolley problem
The protean trolley problem has by now no canonical version. I keep to the original formulation, due to Philippa Foot:
Some years ago, Philippa Foot drew attention to an extraordinarily interesting problem.' Suppose you are the driver of a trolley. The trolley rounds a bend, and there come into view ahead five track workmen, who have been repairing the track. The track goes through a bit of a valley at that point, and the sides are steep, so you must stop the trolley if you are to avoid running the five men down. You step on the brakes, but alas they don't work. Now you suddenly see a spur of track leading off to the right. You can turn the trolley onto it, and thus save the five men on the straight track ahead. Unfortunately, Mrs. Foot has arranged that there is one track workman on that spur of track. He can no more get off the track in time than the five can, so you will kill him if you turn the trolley onto him. Is it morally permissible for you to turn the trolley? (Judith Jarvis Thomson, ‘The Trolley Problem’, The Yale Law Journal, Vol. 94, No. 6 (May, 1985), pp. 1395-1415: 1395; P. Foot, The Problem of Abortion and the Doctrine of the Double Effect, Virtues and Vices, Oxford: 1978.)
Whichever action you take, say to save five persons instead of one, (1) you do not intend to kill anyone; rather (2) if you elect to save five, you merely foresee the death of the one person but would not hesitate to save that person’s life if it were possible; (3) you certainly do not intend that person’s death as a means of saving five (this would not be a case of DDE but of ‘doing evil that good may come of it’ – there is no evil in your intention at all); and (4) it is not ‘disproportionate’ to save five lives instead one as it would be if widespread and intense suffering were the foreseen but unintended consequence of intentionally satisfying an arbitrary and trivial whim.
The trolley problem does not disclose any (internal) inconsistency in DDE, whatever other difficulties or objections the doctrine may face.
The two hospital rooms
The example is under-described:
there are two rooms in a hospital, one with five ill patients who need a gas to save them, and one with a perfectly healthy individual. In injecting gas into the room with ill patients the healthy individual will die due to toxic byproducts from the gas.
I suppose we are to take it, not that the doctor intends to kill the healthy patient in order to save the five sick patients (a case of doing evil that good may come of it) but merely to save the five patients with the foreseen but unintended consequence that the healthy patient will die. This may be ‘understood’ from the context but the extra detail should still go in.
Here again no internal inconsistency is disclosed in DDE. Nor does DDE produce inconsistent results between the two examples: if I cause the death of one person in the trolley case and the death of the healthy patient in the hospital example, how do I act inconsistently ? Your professor’s appeal to legal considerations and to what ‘intuitively the general public believes’ has no bearing on the moral issue of what should be done.
Limitations of DDE
None the less:
The fact that a harm was brought about as a merely foreseen side effect of pursuing a good end does not, all by itself, show that it was brought about permissibly. Other conditions of permissibility must be applied. A principle of proportionality [GT: see quote from Alison Hills above] is often mentioned in this connection, but this must amount to more than the simple requirement to weigh the value of the good end to be achieved against the disvalue of the harmful side effect.
Double Effect is often defended by the use of examples involving contrasting pairs of permissible and impermissible actions. When an author simply describes a harmful side effect brought about permissibly and a very similar result brought about intentionally and impermissibly, then the intuitive confirmation which DDE receives from such examples depends on the assumption that the fact that the harm was a merely foreseen side effect in one of the two cases explains the permissibility of bringing it about in that case. Yet even proponents of DDE would be wise to resist this natural inference, since DDE interpreted in that way would license too much. After all, a doctor who intended to administer a lethal dose of morphine in order to end what was expected to be otherwise unrelievable but temporary suffering (when no terminal illness is present) may not cite the fact that he did not intend to cause death to justify his action! And the strategic bomber cannot defend just any bombing plan that will involve civilian casualties by insisting that the casualties were unintended. What was called a ‘‘Baedeker bomber’’ in World War II, one who targeted sites of cultural value, would act impermissibly though he foresaw but did not intend civilian deaths.
As we have so far formulated it, DDE is entirely reticent about what constitutes a sufficient condition of the permissibility of bringing about a harmful but unintended side effect. It declares the existence of a class of exceptions to a prohibition on causing harm without defining the criteria for membership in that class. Discussions of DDE often mention a proportionality condition which must be satisfied if a merely foreseen harm is to be permissibly brought about. However, two quite different relations are cited as the proportionality condition. Some discuss the proportionality of the value of the aim to the disvalue of the harmful side effect. For instance, The New Catholic Encyclopedia lists as a condition that ‘‘the good effect must be sufficiently desirable to compensate for the allowing of the bad effect.’’ James Sterba says that it must be the case that ‘‘the good consequences are commensurate with the evil consequences.’’ Frances Kamm says that according to the traditional understanding of DE, ‘‘it is permissible to do what is not in itself bad (or omit an act) though this has a bad side effect, if the good we seek to achieve is greater than that bad. (This weighing of good and bad effects is the principle of proportionality.)’’ Others say that the reasons for pursuing the good end must be proportional to the reasons for avoiding the bad side effect. Tom L. Beauchamp lists both versions of the proportionality condition together: ‘‘The good effect must outweigh the bad effect. The bad effect is permissible only if a proportionate reason is present that compensates for permitting the foreseen side effect.’’ (Alison McIntyre, ‘Doing Away with Double Effect’, Ethics , Vol. 111, No. 2 (January 2001), pp. 219-255: 221-2.)
[McIntrye uses the acronym, ‘DE’. I have changed this to ‘DDE’ in line with the quotation from Alison Hills above.]
Although these reflexions on DDE do not show it to be inconsistent in any way, they do expose it as indeterminate. How are we to assess what is ‘sufficiently desirable’? By what metric are we to decide whether ‘the good consequences are commensurate with the evil consequences’? What scales tell us for every situation when a good effect outweighs a bad effect?
McIntyre considers five other limitations on DDE but there is not the space here, unfortunately, to examine and assess them.
Alison Hills, ‘Defending Double Effect’, Philosophical Studies: An International Journal for Philosophy in the Analytic Tradition, Vol. 116, No. 2 (Nov., 2003), pp. 133-152.
Alison McIntyre, ‘Doing Away with Double Effect’, Ethics , Vol. 111, No. 2 (January 2001), pp. 219-255.
Tom L. Beauchamp, Principles of Biomedical Ethics, 4th ed. (Oxford: Oxford University Press, 1994): 207.
Frances Kamm, ‘‘The Doctrine of Double Effect,’’ Journal of Medicine and Philosophy 16 (1991): 571–85, 571–72. I.
James Sterba, ‘‘Introduction,’’ in The Ethics of War and Nuclear Deterrence (Belmont, Calif.: Wadsworth, 1985): 2–3.