1. Natural Law Theory and Human Sexuality
Philosophy 220
Natural Law Theory and Human Sexuality

2. Putting Nature in Natural Law
Natural Law Theory is based on the assumption that there are objective facts about human nature that can serve as the ground for objectively true moral principles.
Because of this, NLT is a value-based moral theory, one that focuses our attention on the value of the intrinsic characteristics of human nature highlighted by the specific version of NLT that is employed.

3. Aquinas on Intrinsic Value
The chief historical proponent of NLT is St. Thomas Aquinas ( ).
According to his theory of human nature, there are four basic intrinsic goods.
Human Life
Human Procreation
Human Knowledge
Human sociability
These four values serve as the basis for his NLT.

4. Basic Principle of NLT
However we conceive of human nature and its intrinsic value, the theory of right action (TRA)of NLT is:
NLT: An action is right if and only if (iff) in performing the action one does not directly violate any of the basic (intrinsic) values.
Thus stated, NLT seems to straightforwardly and non-controversially satisfy both the theoretical and practical aims of Moral Theory. But this picture is more complicated than it first appears.

5. The Doctrine of Double Effect
In many cases, a proposed action both potentially protects one and violates another of the basic values.
To deal with these cases, proponents of NLT rely on the Doctrine of Double Effect.
DDE: An action that would bring about at least one evil and one good effect is morally permissible if and only if:
Intrinsic Permissibility: action (minus effects) is permissible.
Necessity: good effect requires the action.
Nonintenionality: evil effect is not intended
Proportionality: evil effect not out of proportion with good effect.
Example: Ectopic Pregnancy

6. NLT in Context: Catholic Teachings on Sexual Morality
In a series of teachings (notably Casti Connubii and Humanae Vitae), the Roman Catholic church has spelled out the consequences of Aquinas’s version of NLT for a range of human sexual practices.
This is a particularly challenging area in which to apply NLT, as the opening paragraphs of our reading highlight.
Sexuality is clearly a basic and natural part of our humanity, but the Church, for complicated historical reasons, cannot merely affirm it as one of the basic intrinsic goods.

7. What Type of Moral Theory?
Church teachings are further complicated by the fact that in addition to the NLT tradition, it also looks to “divine law” as a justifying basis for its theory of intrinsic value.
This raises the specter of Divine Command theory, which we have already seen provides only dubious foundation for MT.

8. Guiding Principle of Catholic Sexual Morality
Consistently, the church has argued that human nature and the divine law point in the same direction.
From both perspectives, the specific character and dignity of human sexuality is grounded in marriage and “the finality of the function proper to marriage,” in other words, reproduction (80c1).

9. Applications Premarital Relations? Homosexuality? Masturbation?
NO, “any human genital act whatsoever [must] be placed only within the framework of marriage” (80c2).
Homosexuality?
Hell no! The propensity may be natural, but the act is objectively evil, “Homosexual relations are acts deprived of the essential ordination they ought to have” (81c2).
Masturbation?
Tempting, but no, “…masturbation is an intrinsically and seriously disordered act” (82c1), once again because it is counter to the finality that, according to the Catholic tradition of NLT, is consistent with the intrinsic value of sex.