A moral doctrine that permits an action that has both a good and a harmful effect when the harmful effect is foreseen but not intended, provided four conditions are met: (1) the act itself is morally good or neutral; (2) the agent intends only the good effect; (3) the harmful effect is not the means by which the good effect is achieved; and (4) there is a proportionately serious reason to allow the foreseeable harm.

Principle

Permissibility requires satisfying the four conditions: morally acceptable act, right intention (good effect only), no instrumental use of the harm, and proportionality between good and foreseeable harm.

Demonstration

Illustrative scenario — Situation: A patient in intractable pain near end of life. Recognition: Clinician foresees that a high dose of opioid will relieve suffering and may accelerate death but does not intend death. Action: Clinician administers the dose to relieve pain. Consequence: Pain is reduced; death may be hastened as a foreseen but unintended side effect. The action is assessed under the four conditions above.

Misapplication

Treating any foreseeable harmful side effect as intended; e.g., asserting that because death was foreseen, the clinician intended death. The semantic error is collapsing foresight (prediction) into intention (aim), which the doctrine explicitly distinguishes.

Consequence

When correctly applied, the doctrine can justify certain clinically beneficial acts that foreseeably cause harm while preserving a moral distinction from actions that deliberately aim to cause that harm; when misapplied it can obscure responsibility by mislabeling intentions.

Reversal

Does not apply if the harmful effect is used as a means to the good end or is itself intended; also limited where legal regimes define intention or causation differently (for example, when law treats foreseeable hastening of death as intent).

Boundary

Clearly within: administering high-dose analgesia primarily for pain relief when death is foreseen. Boundary case: withdrawing life-sustaining treatment where death follows from cessation — whether the harm is intended or merely foreseen depends on clinical facts and stated aims. Clearly outside: actively administering a lethal agent with the purpose of causing death (intentional euthanasia).

Semantic Tension

Intention-based ethical assessment (focus on agent's aim) ↔ Consequentialist assessment (focus on outcomes); the doctrine privileges the former when distinguishing permissible from impermissible acts.

Synthesis

The doctrine crystallizes a practical moral distinction: permissibility can hinge on the agent’s aim and the role the harmful outcome plays in achieving the good, not solely on the fact that harm was predictable.