Prinzip der Doppelwirkung

Das Prinzip der Doppelwirkung wird in der Regel auf Thomas von Aquin, Summa theologica 2-2, q. 64 a.7 zurückgeführt.


F. J. Connell (1967)

New Catholic Encyclopedia, Vol. 4, New York, S. 1020–22.

“Principle of Double Effect.
A rule of conduct frequently used in moral theology to determine when a person may lawfully perform an action from which two effects will follow, one bad, and the other good.
Conditions. Theologians commonly teach that four conditions must be verified in order that a person may legitimately perform such an act.
1. The act itself must be morally good or at least indifferent.
2. The agent may not positively will the bad effect but may merely permit it. If he could attain the good effect without the bad effect, he should do so. The bad effect is sometimes said to be indirectly voluntary.
3. The good effect must flow from the action at least as immediately (in the order of causality, though not necessarily in the order of time) as the bad effect. In other words, the good effect must be produced directly by the action, not by the bad effect. Otherwise, the agent would be using a bad means to a good end, which is never allowed.
4. The good effect must be sufficiently desirable to compensate for the allowing of the bad effect. In forming this decision many factors must be weighed and compared, with care and prudence proportionate to the importance of the case. Thus, an effect that benefits or harms society generally has more weight than one that affects only an individual; an effect sure to occur deserves greater consideration than one that is only probable; an effect of a moral nature has greater importance than one that deals only with material things.”

Deutsche Übersetzung, zitiert aus Helga Kuhse, Die „Heiligkeit des Lebens“ in der Medizin. Eine philosophische Kritik, Erlangen 1994, S. 118:

„1. Die Handlung selbst muß gut oder zumindest moralisch neutral sein.
2. Der Handelnde darf die schlechte Wirkung nicht positiv wollen, darf sie aber zulassen. Wenn er die gute ohne die schlechte Wirkung erzielen kann, dann sollte er dies tun. Von der schlechten Wirkung sagt man manchmal, sie sei indirekt gewollt.
3. Die gute Wirkung muß von der Handlung zumindest genauso unmittelbar ausgehen wie die schlechte (in der kausalen Abfolge, nicht notwendigerweise in zeitlicher Abfolge). Mit anderen Worten: Die gute Wirkung muß direkt von der Handlung verursacht sein, nicht von der schlechten Wirkung. Andernfalls würde der Handelnde ein schlechtes Mittel zu einem guten Zweck benutzen, was niemals erlaubt ist.
4. Die gute Wirkung muß hinreichend wünschenswert sein, so daß sie das Zulassen der schlechten Wirkung aufwiegt. Bei dieser Entscheidung müssen viele Faktoren abgewogen und verglichen werden, und zwar mit einer Sorgfalt und Umsicht, die der Wichtigkeit des Falls angemessen ist.“



Germain Grisez (1970)

Towards a Consistent Natural Law Ethics of Killing, American Journal of Jurisprudence 15, S. 64–96: S. 78

“A person may guiltlessly do an act having two effects, one good and the other bad, if four requirements are fulfilled simultaneously:
1) If one prescinds from the bad effect, the act must not be evil on another ground. (There is no point in discussing the justifiability of permitting the bad effects of an act which is admitted from the outset to be murder, quite apart from those effects.)
2) The person acting must have a right intention. […]
3) The evil effect may not be the means to the good effect. (One may not kill someone to inherit his wealth with a view to putting it to good use.)
4) There must be a proportionately grave reason for doing the act. (One may not use a possibly deadly drug if a safer one is available and will do.)”



Joseph Boyle (1980)

Toward Understanding the Principle of Double Effect, Ethics 90, S. 527–38. Wiederabgedruckt in The Doctrine of Double Effect. Philosophers Debate a Controversial Moral Principle, hrsg. von P. A. Woodward, Notre Dame 2001, S. 7–20: S. 12.

“In its briefest form it [sc. the PDE] can be stated in the following way: it is morally permissible to undertake an action when one knows that the undertaking will bring about at least one state of affairs such that, if this state of affairs were intrinsic to the action undertaken, the action would be rendered morally impermissible, if and only if (1) the state of affairs is not intrinsic to the action undertaken – that is, it is not intended – and (2) there is a serious reason for undertaking the action.”



Tom L. Beauchamp/James F. Childress (1994)

Principles of Biomedical Ethics, New York, Oxford 1994, 4. Aufl., S. 207.

“According to classical formulations of the RDE, four conditions or elements must be satisfied for an act with a double effect to be justified. Each is a necessary condition, and together they form sufficient conditions of morally permissible action:
1. The nature of the act. The act must be good, or at least morally neutral (independent of its consequences).
2. The agent’s intention. The agent intends only the good effect. The bad effect can be foreseen, tolerated, and permitted, but it must not be intended.
3. The distinction between means and effects. The bad effect must not be a means to the good effect. If the good effect were the direct causal result of the bad effect, the agent would intend the bad effect in pursuit of the good effect.
4. Proportionality between the good effect and the bad effect. 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 bad effect.”



Friedo Ricken (1998)

Allgmeine Ethik, Stuttgart 1998 [3], S. 231f.

„Nach dem heute gängigen Verständnis besagt das PDW: Es ist sittlich erlaubt, ein außermoralisches Übel zu verursachen, wenn folgende vier Bedingungen erfüllt sind:
(1) Die Handlung an sich, d. h. abgesehen von dem in Kauf genommenen Übel, muß sittlich gut oder sittlich indifferent sein. [...]
(2) Die handelnde Person beabsichtigt die gute Wirkung der Handlung; die schlechte Wirkung wird nur zugelassen. [...]
(3) Die schlechte Wirkung darf kein Mittel sein, um die gute Wirkung hervorzubringen. Die schlechte Wirkung darf deshalb nur entweder
(3a) eine Folge der guten Wirkung sein [...], oder
(3b) sie muß sich in gleicher Unmittelbarkeit wie die gute Folge ergeben. [...]
(4) Die Zulassung des Übels muß durch einen entsprechend schwerwiegenden Grund aufgewogen werden.“



F. M. Kamm (2000)

Nonconsequentialism, in The Blackwell Guide to Ethical Theory, hrsg. von Hugh LaFollette, Oxford 2000, S. 205–26: S. 211.

“The doctrine states that we may not intend evil, even when the evil will be a means to a greater good. Nonetheless, we are permitted to employ neutral or good means to promote a greater good, even though we foresee evil side effects if (a) the good is proportionate to the evil and (b) there is no better way to achieve this good.”



Alfonso Gómez-Lobo (2002)

Morality and the Human Goods. An Introduction to Natural Law Ethics, Washington, D. C. 2002, S. 79f.

“The PDE may be formulated as follows:
An action that has two effects, one of which is bad, is morally permissible if and only if the following conditions are satisfied:
(1) The action itself is morally permissible – that is, its main immediate goal is neither to attack an instance of a basic human good nor to fail to prevent a harm. The action itself must follow the moral norms.
(2) The intended good effect will not be obtained by means of the bad effect.
(3) The agent does not intend the bad effect. The bad effect should not be a desired and sought goal. It can be foreseen, predicted, or tolerated, but not directly willed.
(4) There will be a favourable proportion or balance (prudentially judged) between the good and bad effects. If the good effect is minimal (e. g., avoiding an inconvenience or protecting an instrumental good) and the bad effect is significant (loss of a basic good), the action is not morally justified.”



Mark Timmons (2002)

Moral Theory. An Introduction, Lanham, S. 78f.

“Some actions bring about two (or more) effects, one good and one bad, which are both foreseen – hence a “double effect.” The principle of double effect sets forth conditions under which it is morally permissible to perform such actions.

PDE Whenever an action would produce at least one good effect and one bad or evil effect, then one is permitted to perform the act if and only if all of the following conditions are met:
1. The action in question, apart from its effects, must not be wrong.
2. The bad effect must not be intended by the agent. There are two principal ways in which an effect might be intended:
a. Any effect that is a chosen end of action is intended.
b. Any effect that is a means for bringing about some intended end is also intended.
3. The bad effect must not be “out of proportion” to the good effect. What counts as being in or out of proportion cannot be precisely specified, and certainly it would be inconsistent with the thesis of incommensurability to suppose that it is possible to measure degrees of goodness and badness of effects according to some common scale of measurement. However, lack of commensurability does not mean that good and bad effects cannot be compared and judged in the way presupposed by this requirement.”

Bibliographie zum Prinzip der Doppelwirkung (PDF) alphabetisch chronologisch