Doctrine of double effect
Etymology
Rooted in Thomas Aquinas’s 13th-century discussion of self-defense in the "Summa Theologica," where one act has two effects — a good one intended and a bad one foreseen. "Double effect" is a later scholarly name for this Latin-derived distinction between intention and foresight.
noun phrase · /DOK-trin uv DUB-ul ih-FEKT/
The principle that an action causing serious harm can be permissible if the harm is a foreseen side effect rather than the intended means or end.
What it names
A handle for cases where intending a harm and merely foreseeing it seem morally different — reach for it in medical, wartime, and trolley-style dilemmas.
Example
Under the doctrine of double effect, giving a dying patient morphine to ease pain is allowed even if it hastens death, so long as death is not the goal.
Related idea
It leans on the intended/foreseen line that consequentialism rejects — for an outcome-only view, a foreseen death counts the same however it was brought about.