Appendix I

Principle of Double Effect

The principle of double effect is based on the fact that evil must never be directly and voluntarily willed for its own sake and must never be willed either as an end or as a means to an end. Nor may evil ever be directly willed as a foreseen but unwanted consequence. But evil can be reduced to an incidental and unavoidable byproduct in the achievement of some morally licit good the person is rightfully seeking. This principle is most accurately identified by John Hardon, SJ, in Catholic Catechism (1975), p. 337, which states, “To be licitly applied, the principle must observe four limiting norms”:

1. The action (removal of diseased womb) is good; it consists in excising an infected part of the human body.
2. The good effect (saving the mother’s life) is not obtained by means of the evil effect (death of the fetus). It would be just the opposite (e.g., if the fetus were killed in order to save the reputation of an unwed mother).
3. There is sufficient reason for permitting the unsought evil effect that unavoidably follows. Here the Church’s guidance is essential in judging that there is sufficient reason.
4. 4. The evil effect is not intended in itself but is merely allowed as a necessary consequence of the good effect.

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