Double Effect, Principle or Doctrine of

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Originating in Roman Catholic scholastic moral philosophy, the Principle of Double Effect (hereafter referred to as the PDE or Double Effect) is still widely discussed in the bioethics literature on euthanasia, palliative care, physician assisted suicide, suicide and abortion (Barry; Quill, Lo et al.; Manfredi, Morrison et al.; Stempsey; Kamm, 1999; McIntosh; Shaw). It has also been applied to a range of other issues, including organ donation and transplantation (DuBois). Due in large part to these bioethics discussions, the PDE has been the subject of a resurgence of interest in moral and political philosophy generally. Double Effect has been debated in the philosophy of law as germane to discussions of, among other things, murder, self-defense, capital punishment, and suicide (Frey; Hart; Finnis, 1991, 1995; Aulisio, 1996). In social and political philosophy, it has been put forth as an important principle for rights theory (Quinn, 1989; Bole), and as a partial justification for affirmative action (Cooney). A traditional military ethics application of Double Effect, to distinguish between strategic and terror bombing, remains a subject of debate today as well (Bratman; Kamm, 2000). In addition, the PDE's central distinction, intention/foresight, has been the subject of rigorous analysis in the philosophy of action (Robins; Bratman; Aulisio, 1995; Brand; Harman).

Double Effect is typically applied to conflict situations in which any action (or course of actions) will result in numerous effects, good and bad. Traditionally a four-part principle, contemporary versions of the PDE are usually formulated as two-part principles, along the following lines: An action with multiple effects, good and bad, is permissible if and only if (1) one is not committed to intending evil (bad effects) either as end or means, and (2) there is proportionate reason for bringing about the evil (bad effects). The first condition, a non-consequentialist intention condition, is lexically prior to the second. Most proponents of the PDE consider the second condition, the proportionate reason condition, to be consequentialist in nature while allowing for other considerations as well.

Paradigm Applications

In the Roman Catholic bioethics literature, the PDE has long been invoked to deal with cases of maternal-fetal conflict to distinguish between permissible interventions that may result in the death of the fetus and abortion, which is absolutely forbidden (Barry). Consider the following set of maternal-fetal conflict paradigm cases.

Paradigm 1: Therapeutic Hysterectomy. A thirty-three year old pregnant woman is diagnosed with a highly aggressive form of uterine cancer ten weeks into her pregnancy. The woman is a devout Roman Catholic, strongly opposed to abortion, and is under care at a Catholic hospital. If the woman were not pregnant, her doctors would recommend a therapeutic hysterectomy to prevent the spread of cancer.

Paradigm 2: Hypertensive Pregnancy. A thirty-nine year old woman is diagnosed with dangerously life threatening high blood pressure seventeen weeks into her pregnancy. The woman is a devout Roman Catholic, strongly opposed to abortion, and is under care at a Catholic hospital. An abortion would alleviate the hypertension and remove the threat to the woman's life.

Though it may come as a surprise to some, those familiar with the Roman Catholic double effect literature will know that the therapeutic hysterectomy proposed in the first case above has long been considered permissible by orthodox Roman Catholic moralists. Indeed, this is viewed as a paradigm instance of a permissible action under the PDE (Healy; Kelly; O'Donnell). On the traditional view, the physician's intended end would be saving the life of the mother by stopping the spread of cancer through her intended means of removing the cancerous uterus. Fetal death, on the traditional view, would properly be described as a foreseen but unintended (bad) side effect of the (good) act of saving the mother's life.

In contrast, the case of the hypertensive pregnancy has long been considered a paradigm instance of an action that fails the PDE. In particular, the abortion has traditionally been interpreted as the intended means to the good end of saving the life of the mother, thus failing the PDE's lexically prior intention condition (Healy; Kelly; O'Donnell).

The following scenarios illustrate another set of paradigm applications of the PDE, that is, to distinguish between palliative care and euthanasia:

Paradigm 3: Morphine Drip. David, a forty-nine year old HIV patient, is terminally ill and in constant pain. After much discussion with his partner, family, friends and care team, David has decided that he wants only comfort care. He is adamant that he be kept comfortable. David is placed on a morphine drip, which is then periodically adjusted to alleviate David's discomfort. David's physician knows that continued titration to alleviate David's discomfort runs the risk of hastening or even causing death given David's weakened state. David's physician continues to adjust the morphine drip to keep David comfortable.

Paradigm 4: Lethal Overdose. David, a forty-nine year old HIV patient, is terminally ill and in constant pain. After much discussion with his partner, family, friends and care team, David has decided that he no longer wants to go on living. After saying his good-byes to his partner, family, and friends, David asks his physician to give him a lethal injection of morphine. David's physician gives him a lethal overdose of morphine.

Traditionally, Paradigm 3, the Morphine Drip, has been considered permissible under the PDE, while Paradigm 4, the Lethal Overdose, has been considered impermissible. Why? In Paradigm 3, on the traditional view, David's physician's intended end is to alleviate David's pain. The intended means to this end is the administration of a palliative medication, morphine. Given David's excruciating pain and terminal illness, David's physician has proportionate reason to titrate to pain even though he knows this may hasten or even cause death. On the traditional view, should David die, his death is taken to be a foreseen, but unintended, side effect of the doctor's action (Healy; Kelly; O'Donnell).

In Paradigm 4, David's physician has the same end (i.e., to alleviate David's pain). His means, however, is to give David a lethal injection (i.e., to kill him). On the traditional view, Paradigm 4 is taken to fail the intention condition of the PDE because David's death, the bad effect, is intended by his physician as the means to alleviating David's pain. Paradigm 4 is, on the traditional view, a classic instance of mercy killing (Healy; Kelly; O'Donnell).

The application of the PDE to these, and other, types of cases has been challenged. These challenges generally fall into one of three categories: conceptual tenability, practical applicability, and moral significance. Since challenges to the conceptual tenability and practical applicability of the PDE are largely matters for the philosophy of action, they extend well beyond the scope of this entry. In the bioethics literature, challenges to the PDE have focused on its moral significance outside of the absolutist moral framework within which it emerged. In order to understand this type of challenge, however, it is important to consider the historical origins of the PDE.

Historical Origins

In its traditional form, the PDE has four conditions:

  1. The act to be done must be good in itself or at least indifferent.
  2. The good intended must not be obtained by means of the evil effect.
  3. The evil effect must not be intended for itself, but only permitted.
  4. There must be proportionately grave reason for permitting the evil effect. (Fagothey)

Most trace the origins of this traditional four-part PDE and its two-part contemporary successor to St. Thomas Aquinas's (1224–1274) discussion of killing in self-defense (Aquinas; Mangan). Aquinas notes that the Christian tradition had, until his time, almost universally forbidden killing in self-defense. This prohibition probably stemmed from a teaching of St. Augustine (354–430) in De Libero that Christians should not kill others to save themselves because bodily life is that which "they ought to despise" (I, 5 PL 32, 1228). In his justification of killing in self-defense, Aquinas invoked what later became the essential conditions of the PDE. He argued that:

A single act may have two effects, of which only one is intended, while the other is incidental to that intention. But the way in which a moral act is to be classified depends on what is intended, not what goes beyond such an intention. Therefore, from the act of a person defending himself a twofold effect can follow: one, the saving of one's own life; the other the killing of the aggressor. (IIaIIae, q.64, a.7)

Implicit here is the crucial distinction upon which the PDE depends, namely intention/foresight. An act of self-defense is classified as such provided that it is the saving of oneself and not the killing of the aggressor that is intended. If the killing was intended (intendere), and not merely foreseen (praeter intentionem), then, for Aquinas, the act would properly be classified as homicide.

It would seem that both conditions one and three of the traditional PDE might be elicited from this passage. Condition three forbids the intending of an evil effect for itself (as an end). Yet if acts are to be classified according to what is intended, then a violation of condition three (intending the evil as an end) will also be a violation of condition one (the act will be classified as bad in itself). Furthermore, condition two, that the good intended not be obtained by means of the evil, though not explicitly stated, can be understood as a plausible explication of conditions one and three as one who intends an end may also be taken as intending the means to his or her end.

Not to have intended evil is a necessary, but not sufficient, condition of justified self-defense for Aquinas. In the same section he offers a second condition:

An act that is properly motivated may, nevertheless, become vitiated if it is not proportionate to the end intended. And this is why somebody who uses more violence than is necessary to defend himself will be doing something wrong. (IIaIIae, q.64, a.7)

What became the fourth condition of the traditional PDE, the proportionality principle, can be elicited from this passage. Though it is not obvious from this passage, nor from the broader context of Aquinas's work, that proportionate is meant to refer to the measure of good and bad effects, later moralists interpreted the condition in this way.

Double Effect and Contemporary Bioethics

As noted at the outset, the contemporary bioethics literature generally treats Double Effect as a two-part principle. Interestingly, the two-part contemporary PDE, as the preceding discussion suggests, is closer to its Thomistic origins. Though its traditional applications to abortion, euthanasia, self-defense and suicide (particularly physician assisted suicide) continue to be discussed, the PDE has been applied to some novel contemporary bioethics cases, such as the separation of conjoined twins and the use of embryos in research, as well (Coughlan and Anscombe). The strong resurgence of interest in Double Effect in bioethics, however, is directly attributable to the rise of the palliative care movement (Cantor and Thomas; Cavanaugh; Quill, Lo et al.; Manfredi, Morrison et al.; Patterson and Hodges; Preston; Shorr; Gilbert and Kirkham; Sulmasy and Pellegrino; Hawryluck and Harvey; Nuccetelli and Seay; Sulmasy; Bernat; Luce and Alpers; Thorns). Indeed, the vast majority of contemporary bioethics discussion of Double Effect has centered its application to terminal sedation which, though controversial in some quarters, is usually little more than a logical extension of the morphine drip case considered above (Paradigm 3) (Krakauer, Penson et al.; Wein). A somewhat novel application of Double Effect in terminal sedation is illustrated by the following case.

Terminal Sedation: Agonal Breathing. Mrs. Jones, an eighty-two year old white female, is a vent dependent terminally ill cancer patient. She is conscious and deemed to have decision capacity upon psychiatric evaluation. Though her pain is well controlled, she requests to be removed from the ventilator. She also requests to first be sedated so that she will not have the experience of not being able to breathe once ventilator support is withdrawn.

The use of palliative medicine in the case of Mrs. Jones can plausibly be construed as satisfying the PDE. Here the use of palliative medicine is intended to alleviate the discomfort of agonal breathing and the attendant suffering of Mrs. Jones should she have to experience this. Critics have argued that invoking Double Effect in these types of cases is a thinly veiled attempt to avoid the charge of intentional killing (Quill, Dresser et al.; Kuhse). Such critics argue that, rather than invoking Double Effect as a rationalization for palliative care, it should be acknowledged that there are times when the intentional mercy killing (euthanasia) is appropriate, thus rendering Double Effect concerns irrelevant.

Double Effect and Moral Relevance: Curious Artifact or Bulwark?

Many critics of Double Effect and even some of its proponents have focused on its Roman Catholic origins, questioning its moral relevance outside of absolutist Roman Catholicism (Boyle 1991a, 1991b; Quill, Dresser et al.). Indeed, this is the most common challenge articulated in the bioethics literature. What, then, can be said of the moral relevance of the PDE outside of absolutist Roman Catholicism? Should bioethicists outside of Roman Catholic moral tradition view the PDE as little more than the curious invention of sectarian casuistry?

To understand this challenge, it is important to highlight the fact that the Roman Catholic moral tradition, in which the PDE emerged, absolutely prohibits certain types or classes of action, including active euthanasia, abortion, murder, and suicide (Boyle, 1991b). In such a tradition, the question of appropriate act description and classification is of paramount importance. The intention condition of the PDE helps to delimit what counts as falling into a given class of action (recall Aquinas's claim, cited above, that the way an act is to be classified depends on intention). Provided an act does not fall into one of the absolutely forbidden classes of action, one may then apply the proportionate reason condition to help determine the permissibility of bringing about the evil effect. Thus, the moral relevance of the PDE and, in particular, of the intention/foresight distinction, is easy to establish in the context of Roman Catholicism with its absolute prohibitions on certain types of acts.

The claim that Double Effect is morally relevant only within the context of absolutist Roman Catholicism is highly problematic. As discussed above, the most fundamental element of the PDE is a conceptual distinction between intention and foresight. Arguably, the normative significance of any conceptual distinction will depend on the normative framework within which the distinction is operative (Aulisio, 1996, 1997). The central distinction of PDE, intention/foresight, is embedded in ordinary language and common morality, and is arguably important for certain areas of Anglo-American law despite its emphasis on individual autonomy (e.g., law of attempts, distinction between murder one and manslaughter; etc.) (Aulisio, 1996). More importantly, any moral framework, absolutist or not, that incorporates deontic constraints, formulated in terms of intention, on consequentialist considerations may have use of the intention/foresight distinction (and, therefore, the PDE) (Nagel; Kagan; Quinn, 1993; Beauchamp; Kamm, 2001).

If the preceding discussion is on target, given the wide variety of moral frameworks that incorporate deontic constraints formulated in terms of intention, it seems likely that the PDE will continue to be relevant to a range of bioethics issues. This does not mean that proponents of the PDE can rest easily, however. Serious challenges to the PDE remain. Chief among these are challenges to the conceptual tenability and practical applicability of the intention/foresight distinction, and the need for an adequate theory of intention to address these challenges. Though interesting and important in their own right, it seems unlikely that these matters will inhibit continued vigorous bioethics debate concerning the application of the PDE to vexing cases.

mark p. aulisio

SEE ALSO: Abortion, Religious Traditions: Roman Catholic Perspectives; Beneficence; Ethics: Religion and Morality; Life Sustaining Treatment and Euthanasia: Ethical Aspects of; Medical Ethics, History of Europe: Contemporary Period; Palliative Care and Hospice; Right to Die, Policy and Law; Triage


Aulisio, Mark P. 1995. "The Intention/Foresight Distinction." American Philosophical Quarterly 32(4): 341–354.

Aulisio, Mark P. 1996. "On the Importance of the Intention/Foresight Distinction." American Catholic Philosophical Quarterly LXX (2): 189–205.

Aulisio, Mark P. 1997. "One Person's Modus Ponens: Boyle, Absolutist Catholicism, and the Doctrine of Double Effect." Christian Bioethics 3(2): 142–157.

Barry, Robert. 1997. "The Roman Catholic Position on Abortion." Advances in Bioethics 2: 151–82.

Beauchamp, Thomas L., ed. 1996. Intending Death: The Ethics of Assisted Suicide and Euthanasia. Upper Saddle River, NJ: Prentice Hall.

Bernat, James L. 2001. "Ethical and Legal Issues in Palliative Care." Neurologic Clinics 19: 969–987.

Bole, Thomas J. 1991. "The Theoretical Tenability of the Doctrine of Double Effect." Journal of Medicine and Philosophy 16: 467–473.

Boyle, James. 1991a. "Further Thoughts on Double Effect: Some Preliminary Responses." Journal of Medicine and Philosophy 16: 565–-570.

Boyle, James. 1991b. "Who Is Entitled to Double Effect?" Journal of Medicine and Philosophy 16(October): 475–494.

Brand, Myles. 1984. Intending and Acting: Toward a Naturalized Action Theory. Cambridge, MA: MIT Press.

Bratman, Michael E. 1987. Intention, Plans, and Practical Reason. Cambridge, MA: Harvard University Press.

Cantor, Norman L., and Thomas, George C. 1996. "Pain Relief, Acceleration of Death, and Criminal Law." Kennedy Institute of Ethics Journal 6(June): 107–127.

Cavanaugh, Thomas A. 1996. "The Ethics of Death-Hastening or Death-Causing Palliative Analgesic Administration to the Terminally Ill." Journal of Pain and Symptom Management 12: 248–254.

Cooney, William. 1989. "Affirmative Action and the Doctrine of Double Effect." Journal of Applied Philosophy 6: 201–204.

Coughlan, Michael J., and Anscombe, Elizabeth. 1990. "Using People." Bioethics 4: 55–65.

DuBois, James M. 2002. "Is Organ Procurement Causing the Death of Patients?" Issues in Law and Medicine 18: 21–41.

Fagothey, Austin. 1959. Right and Reason. St. Louis, MO: C.V. Mosby Co.

Finnis, John. 1991. "Intention and Side-Effects," In Liability and Responsibility: Essays in Law and Morals, ed. R.G. Frey and Christopher W. Morris. New York: Cambridge University Press.

Finnis, J. 1995. "Intention in Tort Law," In Philosophical Foundations of Tort Law, ed. David G. Owen. New York: Clarendon Press.

Frey, Raymond G. 1975. "Some Aspects to the Doctrine of Double Effect." Canadian Journal of Philosophy 5: 259–283.

Gilbert, James, and Kirkham, Stephen. 1999. "Double Effect, Double Bind or Double Speak?" Palliative Medicine 13: 365–366.

Harman, Gilbert. 1986. Change in View: Principles of Reasoning. Cambridge, MA: MIT Press.

Hart, Herbert L. A. 1982. Punishment and Responsibility. New York: Clarendon Press.

Hawryluck, Laura A., and Harvey, William R. 2000. "Analgesia, Virtue, and the Principle of Double Effect." Journal of Palliative Care 16(Supplement): S24–S30.

Healy, Edwin F. 1956. Medical Ethics. Chicago: Loyola University Press.

Kagan, Shelly. 1989. The Limits of Morality. New York: Oxford University Press.

Kamm, Frances M. 1999. "Physician-Assisted Suicide, the Doctrine of Double Effect, and the Ground of Value." Ethics 109: 586–605.

Kamm, Frances M. 2000. "Justifications for Killing Noncombatants in War." In Life and Death: Metaphysics and Ethics, ed. Peter A. French and Howard K. Wettstein. Boston: Blackwell Publishers.

Kamm, Frances M. 2001. "Toward the Essence of Nonconsequentialism." In Fact and Value: Essays on Ethics and Metaphysics for Judith Jarvis Thomson, ed. Judith Jarvis Thomson, Alex Byrne, Robert Stalnaker, et al. Cambridge, MA: MIT Press.

Kelly, Gerald A. 1958. Medico-Moral Problems. St. Louis, MO: Catholic Hospital Association of the United States and Canada.

Krakauer, Eric L.; Penson, Richard T.; et al. 2000. "Sedation for Intractable Distress of a Dying Patient: Acute Palliative Care and the Principle of Double Effect." Oncologist 5: 53–62.

Kuhse, Helga. 2002. "Response to Ronald M Perkin and David B Resnik: The Agony of Trying to Match Sanctity of Life and Patient-Centered Medical Care." Journal of Medical Ethics 28: 270–272.

Luce, John M., and Alpers, Ann. 2001. "End-of-Life Care: What Do the American Courts Say?" Critical Care Medicine 29: N40–N45.

Manfredi, Paolo L.; Morrison, R. Sean; et al. 1998. "The Rule of Double Effect." New England Journal of Medicine 338: 1390.

Mangan, Joseph. 1949. "An Historical Analysis of the Principle of Double Effect." Theological Studies 10: 41–61.

McIntosh, Neil. 2001. "Withdrawing Life Sustaining Treatment and Euthanasia Debate. Double Effect Is Different from Euthanasia." British Medical Journal (Clinical Research Edition) 323: 1248–1249.

Nagel, Thomas. 1986. The View from Nowhere. New York: Oxford University Press.

Nuccetelli, Susana, and Seay, Gary. 2000. "Relieving Pain and Foreseeing Death: A Paradox about Accountability and Blame." Journal of Medicine and Ethics 28: 19–25.

O'Donnell, Thomas J. 1996. Medicine and Christian Morality. Staten Island, NY: Alba House.

Patterson, James R., and Hodges, Marian O. 1998. "The Rule of Double Effect." New England Journal of Medicine 338: 1389.

Preston, Thomas A. 1998. "The Rule of Double Effect." New England Journal of Medicine 338: 1389.

Quill, Timothy E.; Dresser, Rebecca; et al. 1997. "The Rule of Double Effect—A Critique of Its Role in End-of-Life Decision Making." New England Journal of Medicine 337: 1768–1771.

Quill, Timothy E.; Lo, Bernard; et al. 1997. "Palliative Options of Last Resort: A Comparison of Voluntarily Stopping Eating and Drinking, Terminal Sedation, Physician-Assisted Suicide, and Voluntary Active Euthanasia." Journal of the American Medical Association 278: 2099–2104.

Quinn, Warren. 1993. Morality and Action. Cambridge, Eng.: Cambridge University Press.

Quinn, Warren S. 1989. "Actions, Intentions, and Consequences: The Doctrine of Double Effect." Philosophy and Public Affairs 18: 334–351.

Robins, Michael H. 1984. Promising, Intending, and Moral Autonomy. New York: Cambridge University Press.

Shorr, Andrew F. 1998. "The Rule of Double Effect." New England Journal of Medicine 338: 1389–1390.

Stempsey, William E. 1998. "Laying Down One's Life for Oneself." Christian Bioethics 4: 202–224.

Sulmasy, Daniel P. 2000. "Commentary: Double Effect—Intention Is the Solution, Not the Problem." Journal of Law, Medicine and Ethics 28: 26–29.

Sulmasy, Daniel P., and Pellegrino, Edmund D. 1999. "The Rule of Double Effect: Clearing Up the Double Talk." Archives of Internal Medicine 159: 545–550.

Thorns, Andrew. 2002. "Sedation, The Doctrine of Double Effect and the End of Life." International Journal of Palliative Nursing 8: 341–343.