Reply Obj. 2:  The saying of the Philosopher is to be understood of things that are naturally just, not as general principles, but as conclusions drawn from them, having rectitude in the majority of cases, but failing in a few.

Reply Obj. 3:  As, in man, reason rules and commands the other powers, so all the natural inclinations belonging to the other powers must needs be directed according to reason.  Wherefore it is universally right for all men, that all their inclinations should be directed according to reason. ________________________

FIFTH ARTICLE [I-II, Q. 94, Art. 5]

Whether the Natural Law Can Be Changed?

Objection 1:  It would seem that the natural law can be changed.  Because on Ecclus. 17:9, “He gave them instructions, and the law of life,” the gloss says:  “He wished the law of the letter to be written, in order to correct the law of nature.”  But that which is corrected is changed.  Therefore the natural law can be changed.

Obj. 2:  Further, the slaying of the innocent, adultery, and theft are against the natural law.  But we find these things changed by God:  as when God commanded Abraham to slay his innocent son (Gen. 22:2); and when he ordered the Jews to borrow and purloin the vessels of the Egyptians (Ex. 12:35); and when He commanded Osee to take to himself “a wife of fornications” (Osee 1:2).  Therefore the natural law can be changed.

Obj. 3:  Further, Isidore says (Etym. 5:4) that “the possession of all things in common, and universal freedom, are matters of natural law.”  But these things are seen to be changed by human laws.  Therefore it seems that the natural law is subject to change.

On the contrary, It is said in the Decretals (Dist. v):  “The natural law dates from the creation of the rational creature.  It does not vary according to time, but remains unchangeable.”

I answer that, A change in the natural law may be understood in two ways.  First, by way of addition.  In this sense nothing hinders the natural law from being changed:  since many things for the benefit of human life have been added over and above the natural law, both by the Divine law and by human laws.

Secondly, a change in the natural law may be understood by way of subtraction, so that what previously was according to the natural law, ceases to be so.  In this sense, the natural law is altogether unchangeable in its first principles:  but in its secondary principles, which, as we have said (A. 4), are certain detailed proximate conclusions drawn from the first principles, the natural law is not changed so that what it prescribes be not right in most cases.  But it may be changed in some particular cases of rare occurrence, through some special causes hindering the observance of such precepts, as stated above (A. 4).

Reply Obj. 1:  The written law is said to be given for the correction of the natural law, either because it supplies what was wanting to the natural law; or because the natural law was perverted in the hearts of some men, as to certain matters, so that they esteemed those things good which are naturally evil; which perversion stood in need of correction.