Peter J. Cataldo, Ph.D.

A common decision-making experience that cuts across ordinary life and specific areas such as health care is the choice of an act that has both good and bad effects where there is not merely a general awareness of a risk of the bad effect, but where the bad effect is foreseen yet unintended, and is something that under different circumstances the person would ordinarily avoid as impermissible (a “double effect act”). Historically, as philosophers and theologians in the Catholic moral tradition reflected on the elements of human action and double effect acts, an implicit moral principle gradually developed for evaluating such acts, which became explicitly formulated as the principle of the double effect (“PDE”).¹ This article will identify those components of human action that were historically presupposed by the PDE in the Catholic moral tradition and will suggest that the PDE is best understood and applied as a guide for ensuring what the Catholic tradition comprehended as the integral goodness of a double effect act.

The Principle
The permissibility of double effect acts is morally evaluated through the PDE by the application of four conditions. Each condition depends upon and is best understood within the structures of human action and existence as articulated within the Catholic moral tradition. The historical antecedents of the PDE are usually acknowledged to begin with St. Thomas Aquinas’ treatment of the ethics of self-defense in his Summa Theologica culminating in the explicit articulation of the principle’s fundamental conditions in the work of the classicist theologian Joannes P. Gury, S.J., in 1850.² This article will suggest that the antecedents of the PDE originate in Aristotle and gain essential definition in multiple sources from Aquinas. The traditional four conditions of the PDE are the following:

1. The moral object of the act must good or at least not be intrinsically immoral.
2. The good effect must be intended, even though the bad effect is foreseen.
3. The good effect cannot be caused by the bad effect.
4. The good effect must be proportionate to the bad effect.

As will be shown, in the Catholic moral tradition each condition represents an integral part of a whole. All four conditions, therefore, must be fulfilled and must be applied with the appropriate virtues for a double effect act to be justified. The structures critical for a historical understanding of the four conditions of the principle that will be briefly reviewed here are the natural moral law, voluntary human action; the traditional three sources of the human act; the relation between means and ends; and the responsibility for foreseen and unforeseen consequences.

The Fundamentals of Moral Action
The PDE is historically and ontologically conditioned by what in the Catholic moral tradition is known as the first principle of practical reason within the natural moral law, namely, that all things are ordered toward the good.³ Given this principle, our practical reason is able to recognize the most fundamental obligation of morality: "Good is to be done and pursued, and evil is to be avoided."⁴ The reality of human action is such that this obligation is not fulfilled simply by either doing good or avoiding evil when doing so is uncomplicated, but that the obligation is also in force when the pursuit of good is inextricably tied with evil in double effect acts. Thus, a fundamental moral goal of the PDE is to guide the moral agent to pursue and achieve good even though this effort is inseparably connected with evil that is foreseen as likely.⁵

As with any moral obligation, fulfilling the first rule of the natural moral law presumes voluntary moral agency where there is adequate knowledge and free choice of the will.⁶ However, there are situations and actions in which the voluntary status of the act may not be clear, in particular the intent of the agent. Aristotle recognized this in his classic example of a ship in a storm: “Something of the sort happens also with regard to the throwing of goods overboard in a storm; for in the abstract no one throws goods away voluntarily, but on condition of its securing the safety of himself and his crew any sensible man does so . . . .”⁷ Here, Aristotle recognized that an act that has a good effect (e.g., saving life) may also have a bad effect (e.g., destruction of goods), which considered in itself is not permissible and as such is not intended. Such an act is voluntary but has a “mixed” status because the good effect cannot be obtained without the foreseen but unintended bad effect. Thus, the essential elements of the PDE — a good or indifferent act with good and bad effects, foreseeing but unintending the bad effect, and a proportionality between the good and bad effects — are present in Aristotle’s account of voluntariness.⁸

The historical antecedents of the PDE are also found in Aquinas’ example of the part-whole relationship and in his view of lethal force. In his ethical analysis of causing physical injury to oneself or another, Aquinas explains that

. . . a member of the human body is of itself useful to the good of the whole body, yet, accidentally it may happen to be hurtful, as when a decayed member is a source of corruption to the whole body. Accordingly so long as a member is healthy and retains its natural disposition, it cannot be cut off without injury to the whole body.⁹

The implication of this argument is that a decayed member may be cut off to preserve the whole of the body.¹⁰ This is permissible even though the bad effect of losing a member is foreseen. The surgical act of amputation is not immoral because while a human limb is intrinsic to the good of the whole body, in particular cases that intrinsic status is accidentally altered by disease. Hence, even though the bad effect of losing a limb is foreseen, the loss qua particular part within the whole need not be intended and in fact is not what is intended.¹¹ Moreover, the good effect of preserving the health of the whole is proportionate to the bad effect of losing a limb.¹²

Aquinas’ account of the ethics of self-defense highlights the components of intention, nature, and proportionately found in the PDE:

. . . the act of self-defense may have two effects, one is the saving of one's life, the other is the slaying of the aggressor. Therefore this act, since one's intention is to save one's own life, is not unlawful, seeing that it is natural to everything to keep itself in "being," as far as possible. And yet, though proceeding from a good intention, an act may be rendered unlawful, if it be out of proportion to the end. Wherefore if a man, in self-defense, uses more than necessary violence, it will be unlawful: whereas if he repel force with moderation his defense will be lawful. . . .¹³

An act of physical force taken in self-defense can have the good effect of saving one’s life and the bad effect of killing the aggressor. Such an act is good in itself (per se) consistent with the natural moral law. The good effect of saving life is intended and the killing of the aggressor is incidental to the act of self-defense. To confirm that the killing is an incidental effect, Aquinas includes a proportionality test to ensure that no more violence than is necessary is used. If disproportionate force is used, then this is evidence that the killing is not an incidental effect of the act and is itself intended.¹⁴

This attention to due circumstances in the ethical evaluation of self-defensive actions points up that the traditional three determinants of a moral act are another fundamental factor for understanding the traditional version of the PDE. These determinants or fonts are the moral object of the act, the intention of the agent, and the circumstances of the act. When each of these elements achieves its own good, the moral goodness of an act forms an integral whole. For an act to be completely good, all three fonts must be good, but a defect in only one component is enough to make the act morally bad. This is a principle of human action recognized by Aristotle and used throughout the Catholic moral tradition.¹⁵ The moral integrity of an act is actually reflective of the way it exists on an ontological level. As all things have a potential for what Aquinas calls “the fullness of being” (plenitudo essendi), so also does the human act possess a fullness or wholeness of its being as constituted by its object, intended ends, and its due circumstances.¹⁶ No one moral font by itself can account for an act’s fullness of being, but only together do they constitute its fulness. As will be shown, the PDE is best understood as a guide to preserve the unity and integral goodness or fullness of being of a double effect act.¹⁷

The moral object of an act in the Catholic moral tradition refers to the act’s delimited moral content that constitutes its moral nature or species within an objective moral order; for example, theft, self-defense, murder, adultery, or lying.¹⁸ Intention is an act of the will that tends in an ordered relation toward something as its terminus (or “end”) guided by reason. An intermediate terminus toward which the will tends is known as a means and is also known as the proximate or immediate end which is ordered to an ultimate terminus or remote end.¹⁹ Moreover, to intend a remote or ultimate end is necessarily to intend the means to that end.²⁰

Intention should not be conflated with foresight. Traditionally, these were regarded as operations of two different powers: intention as an act of the will, foresight as an act of the intellect.²¹ Therefore, to foresee a bad consequence in a double effect act is not necessarily to intend it. Related to intention but distinct from it in assessing responsibility is any additional willingness for an effect. For Aquinas, the consequences of an external act can increase or decrease the goodness or badness that an act already has from its object depending on whether the effects are foreseen, and if unforeseen, whether they are incidental or should have been foreseen when the consequences follow from the nature of the act.²² The conditions of the PDE in part help to ensure the overall integral good of a double effect act by determining whether the act truly has a double effect or whether the foreseen bad effect defines the nature of the act.²³

Aquinas defines the circumstances of an act in this way: “Whatever conditions are outside the substance of an act [moral object], and yet in some way touch the human act, are called circumstances.”²⁴ How the circumstances of an act are configured with each other is important for its ethical assessment: “Everything that is directed to an end should be proportionate to that end. But acts are made proportionate to an end by means of a certain commensurateness, which results from the due circumstances.”²⁵ Assessing the voluntariness of an act is also determined by knowledge or ignorance of its circumstances.²⁶ Circumstances are categorized as “who, what, where, by what aids, why, how, and when” and touch the act itself, the cause of the act, and the act’s effect.²⁷

Ensuring Integral Goodness
The PDE implicitly integrates all tenets of the Catholic moral tradition identified here: the first principle of the natural moral law — to do good and avoid evil; the voluntary status of acts in which pursing good is inextricable with avoiding evil; and the centrality of an act’s object, intention, and circumstances. The PDE is best understood as designed to preserve the integrity of the goodness of an act in its three fonts where there are both foreseen good and bad effects.²⁸

This is evident from the way in which the three traditional determinants of a moral act overlay with the four conditions of the PDE.²⁹ As with any human act, the moral nature of a double effect act is derived from its object. The first condition of the PDE ensures that the act’s object is good or at least is not immoral. For a double effect act to be good, the agent must intend a morally good object in the proximate end or means, a remote end that is good, and only particular effects that are good (second condition). Foreseeing the bad effect(s) does not disrupt the integrity of the act because foreseeing a consequence does not necessarily entail that the effect is intended, and because the nature of the act is such that it has multiple effects both good and bad.

Finally, the third and fourth conditions of the PDE pertain to the third font, the circumstances of the act, and specifically those circumstances that correspond to the act’s causes, its effects, and the act itself. Among the circumstances relating to the effects of the act, the bad effect cannot be a cause of the good effect in any way, either as a final, material, or efficient cause. With respect to the circumstances relating to the effects and the act itself, for example, there must be a due proportion among the nature of the effects and their moral status and among circumstances such as the timing of the act and how or in what manner the act is performed. Understood against the backdrop of the notion of the integrity of goodness and in light of other fundamental structures of human action, the PDE was never designed as a comprehensive moral principle but as a threshold test for the moral wholeness of a double effect act.³⁰

The three-font foundation of the PDE ensures that all circumstances touching upon object, intention, foresight, causality, and effects of a double effect act achieve an overall commensurateness with the ultimate end of the act and thereby preserve the integrity of its goodness and the fullness of its being.³¹ Hence, by applying the PDE through the lens of an act’s integrity it can be shown how, for example, the PDE preserves the integral goodness of removing a gravid cancerous uterus threatening the life of the mother.³² The act’s integral goodness is evident in the status of the following components: Removing the threat of cancer as the act’s object is morally good; the good effect of removing a diseased uterus and the remote end of preserving life are all intended; the death of the fetus is foreseen but not intended; the death of the fetus is not the cause of the good effect of removing a diseased uterus; and there is a relational circumstance between the goodness of the good effect and the wrongness of the bad effect such that the good effect is proportionate to the bad effect. The good of saving the mother — the only life that can be saved under the circumstances — through a procedure that conserves the lives of both mother and child to the extent possible and is not defined by the killing of the child, represents a proper proportionality of the good effect in relation to the bad effect.

The understanding of the PDE articulated here as being conditioned by the classical view of the three moral determinants of an act provides a helpful hermeneutic to interpret both contemporary views of the traditional principle and contemporary reformations of it. As a guide for preserving the integral goodness of a double effect act, its central thesis is not focused on one element of action, such as intentionality around the bad effect. Thus, the main purpose of the PDE is not to block the transfer of the impermissibility of other (non-double effect) acts that have bad effects similar to the bad effect in a double effect action.³³ Given the multifactorial foundation of the PDE, it is not reducible to any one relation within the structure of human action or to any particular traditional condition or combination of conditions. For example, the PDE is not reducible to the epistemological relation between foreseeable and intended effects,³⁴ or to its second and third conditions, or to a principle about intentionality.³⁵ Similarly, the PDE cannot be reduced to a psychological relation between foreseeable and intended effects.³⁶

The PDE emerged from the multifaceted nature of human action within the Catholic moral tradition. Among the various components of this view of human action is the fundamental recognition that the goodness of action forms a unified, integral whole. Given these historical sources of the principle, the essential purpose of the PDE is best understood and applied as a principle for ensuring the integrity of goodness of double effect acts.³⁷

Peter J. Cataldo, Ph.D.
Senior Vice President, Theology and Ethics
Providence
[email protected]

ENDNOTES

1. All uses of “PDE” will refer to the traditional formulation and understanding of the principle, unless otherwise specified. I also use the definite article, “the,” in the title of the principle because this was the traditional form used and because it captures the thesis of this analysis that the PDE is not a principle for assessing side effects but for assessing the unified integral goodness of double effect acts.
2. For an authoritative history of the PDE, see Joseph T. Mangan, S.J., "An Historical Analysis of the Principle of Double Effect,” Theological Studies 10, 1 (February 1949): 41 – 61; see also T. A. Cavanaugh, Double-Effect Reasoning: Doing Good and Avoiding Evil (Oxford: Clarendon Press, 2006); and T. Lincoln Bouscaren, S.J., Ethics of Ectopic Operations, Second Edition (Milwaukee, WI: The Bruce Publishing Co., 1944): 30 – 38.
3. Aristotle first articulated the core of the natural moral law in his Nicomachean Ethics: "Every art and every inquiry, and similarly every action and pursuit, is thought to aim at some good; and for this reason the good has rightly been declared to be that at which all things aim": Aristotle, Nichomachean Ethics, tr. W.D. Ross, (Oxford: Clarendon Press, 1925), I, 1 (1094a 1). St. Thomas Aquinas, building on Aristotle, described the essence of the natural moral law in this way: “. . . every agent acts for an end under the aspect of good. Consequently, the first principle of practical reason is one founded on the notion of good, viz. that "good is that which all things seek after." Aquinas, Summa Theologica, trs. Fathers of the English Dominican Province (New York: Benziger Bros., 1947), I-II, q. 94, a. 2.
4. Summa Theologica, I-II, q. 94, a. 2.
5. For an excellent examination of the role of the natural moral law in the PDE, the causal structures of the moral act, and their relational significance as they function in the PDE, see Jean Porter, “Choice, Causality, and Relation: Aquinas’s Analysis of the Moral Act and the Doctrine of Double Effect,” American Catholic Philosophical Quarterly 89, 3 (June 2015): 479-504. See Alison McIntyre, “Doing Away with Double Effect,” Ethics 111 (January 2001): 233, “. . . it [PDE] is addressed to well-intentioned agents who wonder what they may do to further a good end.” McIntyre introduces six “constraints” on the application of the PDE to address what she argues are problems with the way that proponents of the PDE treat the difference between intentionality and foresight.
6. Summa Theologica, I-II, q. 6, a. 1. A voluntary act is described as a human act as opposed to an act of a human; see Summa Theologica, I-II, q. 18, a. 8.
7. Aristotle, Nichomachean Ethics, III, 1 (1110a 5). Aristotle describes this case as an example of acting out of fear of greater evils. This description can be understood as later becoming the principle of lesser evils, which is related to the PDE.
8. Consistent with Aristotle, the voluntary status of a double-effect act was categorized in the manualist tradition as “indirectly voluntary”; see, for example, Dominic M. Prümmer, O.P., Handbook of Moral Theology, trs. G.W. Shelton, S.T.L. (Cork: The Mercier Press, 1956): 13 – 14; John A. McHugh, O.P. and Charles J. Callan, O.P., Moral Theology, Vol. 1, Edward P. Farrell, OP, ed. (New York: Joseph F. Wagner, 1958): 16 – 17.
9. Summa Theologica, II-II, q. 65, a. 1.
10. See Summa Theologica, II-II, 64, 2: “For this reason we observe that if the health of the whole body demands the excision of a member, through its being decayed or infectious to the other members, it will be both praiseworthy and advantageous to have it cut away.”
11. Aquinas’ analysis shows an additional foundational element for understanding the PDE; namely, the distinction between the per se nature of something and its per accidens state, which was pervasive throughout classical thought. For an example of how this distinction is relevant for understanding the PDE, see Mangan, S.J., “An Historical Analysis of the Principle of Double Effect,” 49, 53, 55, 57 – 58.
12. The manualists in the Catholic moral tradition generally recognized five standards for assessing the proportionate gravity of the reason(s) for tolerating the bad effect in double effect acts: the degree of badness of the effect; the degree of dependence of the bad effect on the act; the proximity of the effect to the bad act; the degree of certainty that the bad effect will occur; and the degree of obligation to prevent the bad effect. See, for example, John A. McHugh, O.P., and Charles J. Callan, O.P., Moral Theology, 38 – 39.
13. Summa Theologica, II-II, q. 64, a. 7.
14. In the same article (as well as a. 3), Aquinas argues that it is morally permissible for a public authority to intend to kill as a means to preserve the common good. This is not a double effect situation insofar as the killing is deemed morally good.
15. See Aristotle, Nichomachean Ethics, II, 6 (1106b, 28 – 35): “Again, it is possible to fail in many ways . . . while to succeed is possible only in one way . . . . For men are good in but one way, but bad in many”; Aquinas, Commentary on Aristotle’s Nichomachean Ethics, trans. C.I. Litzinger, O.P. (Notre Dame, IN: Dumb Ox Books, 1993), II, 7, 319 – 321 (pp. 107 – 108): “. . . good results from a united and complete cause but evil from any single defect. . . . “goodness will be present only when all the circumstances are rightly ordered”; see also Aquinas, Commentary on Aristotle’s Nichomachean Ethics, I, 12, 139 – 140; see Aquinas, On Evil, trs. John A. Oesterle and Jean T. Oesterle (Notre Dame, IN: University of Notre Dame Press, 1995), II, a. 4, ad 2 (p. 62): “And hence it is that an evil act cannot become good, for from whichever [of these defects] the act is evil, it cannot be an integral good; but a good act can become evil because it is not required that it be an integral evil, but it is sufficient that it be evil in some particular respect”; see also, for example, Aquinas, On Evil, VIII, a. 4; X, a. 1; XVI, a. 6, ad 11; see also Summa Theologica, I-II, q. 19, a. 6, ad 1; and see Summa Theologica, I-II, q. 18, 4, ad. 3: “Nothing hinders an action that is good in one of the way[s] mentioned above, from lacking goodness in another way. And thus it may happen that an action which is good in its species or in its circumstances is ordained to an evil end, or vice versa. However, an action is not good simply, unless it is good in all those ways: since "evil results from any single defect, but good from the complete cause," as Dionysius says (Div. Nom. iv).” Christopher Kaczor in “Double-Effect Reasoning from Jean Pierre Gury to Peter Knauer,” Theological Studies 59 (1998): 299, recognizes that Aquinas’ analysis of self-defense in Summa Theologica, II-II, q. 64, a. 7 presupposes his examination of the principles of human action earlier in the Summa at I-II, q.18, but he does not make the additional point that for Aquinas these principles are integral to the unity of a good moral act.
16. See Summa Theologica, I-II, q. 18, a. 1-3; articles 4 – 11 also indirectly address the fullness of human action as good. See Jan A. Aertsen, “Thomas Aquinas on the Good: The Relation between Metaphysics and Ethics,” in Aquinas’s Moral Theory: Essays in Honor of Norman Kretzmann, eds. Scott MacDonald and Eleonore Stump (Ithica, NY: Cornell University Press, 1999): 243 – 247. Analogous to the unity of the goodness of a moral act is the unity of a human act in its operations; see Summa Theologica, I-II, q. 17, a 4. See also Ralph McInerny, Aquinas on Human Action: A Theory of Practice (Washington, D.C.: The Catholic University Press of America Press, 2012): 69: “. . . a single human act contains many parts which are only potentially many; some of them actually come to be separate wholes when something goes wrong.”
17. The preservation of this unity of a double effect act through the application of the PDE is why the PDE is appropriately described as a principle. Cavanaugh, Double-Effect Reasoning (p. xx, n.) uses “double-effect reasoning” rather than referring to the principle of the double effect because he regards it as being more a set of criteria than a principle, and because use of “principle” reinforces the erroneous reduction to one of the criteria. However, given that preserving the integrity of goodness is the central purpose of the PDE, the principle is not simply about the reasoning of an agent but also pertains to the moral and ontological wholeness of a double effect act.
18. Summa Theologica, I-II, q. 18, a. 2.
19. Summa Theologica, I-II, q. 12, a. 2, a. 3, a. 4.
20. This follows from the very structure of intention as an ordering of one terminus to another. See Summa Theologica, I-II, q. 12, a. 4: “. . . the will is moved to the means for the sake of the end: and thus the movement of the will to the end and its movement to the means are one and the same thing. For when I say: "I wish to take medicine for the sake of health," I signify no more than one movement of my will. And this is because the end is the reason for willing the means.”
21. There are other differences as well; see Cavanaugh, Double-Effect Reasoning: Doing Good and Avoiding Evil, 97, 107.
22. Summa Theologica, I-II, q. 20, a 5. Even though to foresee is not necessarily to intend, in some cases one can still be responsible for foreseen effects, even if they are not intended; see G.E.M. Anscombe, “Modern Moral Philosophy,” Philosophy 33, 124 (January 1958): 11. See Gareth B. Matthews, “Saint Thomas and the Principle of Double Effect,” in Aquinas’s Moral Theory: Essays in Honor of Norman Kretzmann, eds. Scott MacDonald and Eleonore Stump (Ithica, NY: Cornell University Press, 1999): 72 – 74 for a critique of the view that, unlike double effect actions, Aquinas held that when one’s act has one bad effect that follows from the nature of an act it need not be intended.
23. Willingness based on the status of whether the consequences of an act are foreseen can be said to pertain to other operations of the will in addition to intention; namely, counsel, consent, and choice. See Summa Theologica, I-II, qs. 13, 14, 15.
24. Summa Theologica, I-II, q. 7, a. 1.
25. Summa Theologica, I-II, q. 7, a. 2.
26. Summa Theologica, I-II, q. 7, a. 2.
27. Summa Theologica, I-II, q. 7, a. 3.
28. On this interpretation, the PDE is not adequately characterized as a moral rule arising from a consideration to avoid doing moral evil as is argued, for example, by Alexander R. Pruss, “The accomplishment of plans: a new version of the principle of double effect,” Philosophical Studies: An International Journal for Philosophy in the Analytic Tradition 165, 1 (August 2013): 49, 58.
29. See Peter J. Cataldo, “The Principle of the Double Effect,” Ethics & Medics: A Catholic Perspective on Moral Issues in the Health and Life Sciences” 20, 3 (March 1995): 1 – 3; see also Peter J. Cataldo, review of P.A. Woodward, ed., The Doctrine of Double Effect: Philosophers Debate a Controversial Moral Principle (Notre Dame, IN: University of Notre Dame Press, 2001) in The National Catholic Bioethics Quarterly (Summer 2004): 436.
30. For an account about what ought not to be expected from the PDE, see Heidi M. Giebel, “The Limits of the Double Effect,” Proceedings of the American Catholic Philosophical Association, ed., Mirela Oliva (Houston, TX: American Catholic Philosophical Association): 143 – 157. G.E.M. Anscombe, “Medalist’s Address: Action, Intention, and ‘Double Effect,'” in P.A. Woodward, ed., The Doctrine of Double Effect: Philosophers Debate a Controversial Moral Principle, 64 – 65 argues that additional principles are needed “on which to judge the unintended causing of death.” An example of such a principle might be the “intrinsic certainty of the death of the victim.” Anscombe’s observation is true insofar as it pertains to whether an effect defines the nature of the act, and I would submit that such subprinciples are implicitly present in the conditions of the PDE that account for the due proportion of circumstances.
31. See Summa Theologica, I-II, q. 18, a. 3, where Aquinas relates the circumstances of an act to the fullness of its being: “Now, everything that is directed to an end should be proportionate to that end. But acts are made proportionate to an end by means of a certain commensurateness, which results from the due circumstances. In natural things, it is to be noted that the whole fulness of perfection due to a thing, is not from the mere substantial form, that gives it its species; since a thing derives much from supervening accidents, as man does from shape, color, and the like; and if any one of these accidents be out of due proportion, evil is the result. So it is with action. For the plenitude of its goodness does not consist wholly in its species, but also in certain additions which accrue to it by reason of certain accidents: and such are its due circumstances. Wherefore if something be wanting that is requisite as a due circumstance the action will be evil.”
32. For a defense of the PDE against critiques in the context of other typical issues in medical ethics see Daniel P. Sulmasy and Edmund D. Pellegrino, “The Rule of Double Effect: Clearing Up the Double Talk,” Archives of Internal Medicine 159 (March 22, 1999): 545 – 550. While Sulmasy and Pellegrino correctly present the PDE, they mistakenly hold that the PDE cannot be used together with other traditional principles, such as the principle of ethically proportionate and disproportionate means of sustaining life, to morally evaluate actions such as physician assisted suicide and terminal sedation.
33. See Joseph Boyle, “Intention, Permissibility, and the Structure of Agency,” American Catholic Philosophical Quarterly 89, 3 (2015): 461 – 478; Germain Grisez, The Way of the Lord Jesus: Christian Moral Principles, Volume 1, (Chicago: Franciscan Herald Press, 1983): 299.
34. See Neil Delany, “To Double Business Bound: Reflections on the Doctrine of Double Effect,” American Catholic Philosophical Quarterly 75, 4, (Fall 2001): 561 – 583; David S. Oderberg, “The Doctrine of Double Effect,” in A Companion to the Philosophy of Action, eds. Timothy O'Connor Constantine Sandis, (Oxford: Wiley-Blackwell Publishing, 2010): 324-330; Lawrence Masek, “In Defense of a Minimalist, Agent-Based Principle of Double Effect,” American Catholic Philosophical Quarterly (June 2015): 521 – 538; Michael S. Moore, Causation and Responsibility: An Essay in Law, Moral, and Metaphysics (Oxford: Oxford University Press, 2009): 42 – 51; Tom L. Beauchamp and James F. Childress, Principles of Biomedical Ethics, Sixth Edition (New York: Oxford University Press, 2009): 162; Philip A. Reed, “The Danger of Double Effect,” Christian Bioethics 18, 3, (2012): 287 – 300; Reed also makes the claim that the PDE is abused because its conditions are inherently disposed for abuse. This claim can in part be countered by an adequate understanding of the central components of human action within the Aristotelian-Thomistic tradition, including the integrity of goodness, and how they form the conditions of the PDE and are preserved by the PDE in double effect action.
35. For views that reduce the PDE to its second and third conditions see, Joseph M. Boyle, Jr., “Toward Understanding the Principle of Double Effect,” in P.A. Woodward, ed., The Doctrine of Double Effect: Philosophers Debate a Controversial Moral Principle, 7 – 20; Philip A. Reed, “How to Gerrymander Intention,” American Catholic Philosophical Quarterly (June 2015): 441 – 460. For views that reduce the PDE to a principle of intentionality see, Timothy E. Quill, Rebecca Dresser, Dan W. Brock, “The Rule of Double Effect — A Critique of Its Role in End-of-Life Decision Making,” The New England Journal of Medicine 337, 24 (December 11, 1997): 1768 – 1771; Warren S. Quinn, “Actions, Intentions, and Consequences: The Doctrine of Double Effect” in P.A. Woodward, ed., The Doctrine of Double Effect: Philosophers Debate a Controversial Moral Principle, 23 – 40; Jonathan Bennett, Foreseen Side Effects versus Intended Consequences,” in P.A. Woodward, ed., The Doctrine of Double Effect: Philosophers Debate a Controversial Moral Principle, 85 – 118; Nancy Davis, “The Doctrine of Double Effect: Problems of Interpretation,” in P.A. Woodward, ed., The Doctrine of Double Effect: Philosophers Debate a Controversial Moral Principle, 119 – 142; Philippa Foot, “The Problem of Abortion and the Doctrine of the Double Effect,” in P.A. Woodward, ed., The Doctrine of Double Effect: Philosophers Debate a Controversial Moral Principle, 143 – 155; Donald B. Marquis, “Four Versions of Double Effect,” in P.A. Woodward, ed., The Doctrine of Double Effect: Philosophers Debate a Controversial Moral Principle, 156 – 185.
36. See Neil Sinhababu, “Unequal Vividness and Double Effect,” Utilitas 25, 3, (September 2013): 291 – 315.
37. For an important study of the historical sources for Jean Pierre Gury’s formulation of the PDE, see Julia Fleming, “Jean Pierre Gury’s Sources: A Missing Chapter in the History of Double Effect,” Theological Studies 74 (2013): 420–441. In my view, Fleming correctly concludes that “For Gury and his sources, the critical question regarding the indirect voluntary [e.g., a double-effect act] was not whether an action was direct or indirect, but whether a particular indirect action was licit or illicit” (p. 441). The historical reason for this view by Gury and his sources is that their principles crucially assumed a unity of the three fonts of a moral act which preserves its integral goodness.