Killing is the descriptive superordinate class of all actions that actively bring about the death of a human being. It is not a moral value-determination, but a classification of the state of affairs. The ethical assessment of each form of killing depends on its object — on what the acting person willingly does.
Moral differentiation
With Thomas Aquinas (Summa Theologiae II-II, q.64), the Catholic tradition has held a differentiated doctrine of killing since the thirteenth century:
- Intrinsically evil (intrinsece malum): The direct and intentional killing of an innocent human being — murder (German). This form contradicts human nature essentially and cannot be dispensed by any authority. Veritatis Splendor 80 (John Paul II) counts it among the acts that are morally evil “always and per se, that is, on account of their very object.”
- Morally permissible under conditions: Killing in self-defense to protect one’s own life or that of innocent third parties; killing in a just war under the conditions of the bellum iustum doctrine. In both cases the killing is the consequence of an action directed at protection, not its object — the doctrine of double effect (Thomas, q.64 a.7).
Reducing the doctrine of killing to “killing = always evil” misses the personal-ontological differentiation; reducing it to “killing is always a question of consequentialism” misses the Personalist Norm and the concept of the intrinsically evil act.
Distinction: killing versus withdrawal of treatment
A constitutive ethical distinction — especially in intensive-care and transplantation medicine — is that between active killing and withdrawal of treatment (WLST):
- Active killing sets the cause of death (e.g. a lethal substance).
- Withdrawal of treatment allows dying by ending a measure that merely prolongs the dying process; the cause of death lies in the underlying illness, not in the action.
This distinction is constitutive for the ethical profile of intensive-care medicine and in particular of donation after circulatory death (DCD): the organizational separation of the WLST decision from any DCD consideration protects the person from becoming a means of organ procurement.
Bioethical relevance
The class killing anchors several bioethical controversies in which the question of the object is central:
- Abortion: the intentional killing of an innocent human being from fertilization onward — intrinsically evil.
- Active euthanasia: intentional killing on request — qualified by the Catholic tradition as intrinsically evil (cf. Iura et bona, Congregation for the Doctrine of the Faith, 1980).
- Suicide and assisted suicide: the killing of one’s own person as the object of the action — violates the right to life in one’s own person.
- Capital punishment: killing in the execution of punishment — qualified by John Paul II (Evangelium vitae 56) and Francis (Catechism, 2018) as no longer justifiable.
Ontological classification
Superordinate concept: State of affairs
Subclasses:
- Murder (German) (the direct and intentional killing of the innocent — intrinsically evil)
- (further: self-defense, killing in a just war, suicide, killing on request)
Related concepts:
Chapter assignment: Chapter 4: What Is Human Personhood? (German), Chapter 5: Oblivion of the Person (German)
Sources: Generated by querying the Personhood ontology.
Further sources:
- Thomas Aquinas: Summa Theologiae, II-II, q.64. The classical locus for the doctrine of killing and the doctrine of double effect.
- Congregation for the Doctrine of the Faith (1980): Iura et bona — Declaration on Euthanasia.
- John Paul II (1993): Veritatis Splendor, no. 80. The concept of the intrinsically evil act.
- John Paul II (1995): Evangelium vitae. The magisterial synthesis of the doctrine of killing.