What is Natural Law Ethics?

Natural Law Ethics, also known as Thomistic Ethics, was developed by St. Thomas Aquinas during the medieval period. Its fundamental principle is that reason serves as the origin of moral law, guiding individuals towards what is considered good. Aquinas defined 'the good' as the ultimate goal of human actions, inherently discoverable within one's own nature. The core directive of this ethical model is to do good and avoid evil.

An action is deemed morally right if it aligns with moral law, which, for Aquinas, is dictated by reason and originates from God's eternal law. This divine law, expressed in human nature, instructs us to 'do good and avoid evil.' Conscience, understood as the inner voice of intellect or reason, guides individuals to follow this moral law. An action obeys conscience if it satisfies the three natural inclinations: self-preservation, just dealing with others, and propagation of the human species.

The three natural inclinations are crucial in determining moral actions. Self-preservation means taking care of one's health and avoiding self-harm, making suicide morally wrong. Just dealing with others involves treating everyone with respect, condemning acts like exploitation, deception, and murder. Propagation of human species pertains to the natural design of reproductive organs for reproduction, rendering acts that frustrate this purpose, such as masturbation, immoral. If any of these inclinations are violated, an act is considered immoral.

Aquinas identified three elements that determine the morality of a human act: the object of the act, its circumstances, and its end. The object is the primary intention of the will. Circumstances are conditions that can aggravate or mitigate the act's morality, encompassing factors such as the person doing the act, the nature of the moral object, place, means, reason, manner, and time. The end refers to the doer's purpose, which, if selfish, can render an otherwise good act morally wrong. For an act to be considered morally right, all three determinants must be good.

Aquinas formulated the principle of double effect to address situations where an action produces both good and evil results. The four principles are: 1) The intended action must be good or morally indifferent. 2) The good effect must follow as immediately as the evil effect, or both must occur simultaneously. 3) The evil effect must not be intended but merely permitted to occur. 4) There must be a proportionate and sufficient reason for allowing the evil effect. All four principles must be satisfied for an action to be considered morally right. An example is the removal of a cancerous uterus from a pregnant woman, which saves her life (good) but results in the death of the fetus (evil), often considered morally permissible under these principles. Conversely, an act like killing a drug lord, while potentially bringing societal benefits, is considered intrinsically immoral if the act itself (killing) violates the first principle.