SECOND ARTICLE [I-II, Q. 91, Art. 2]

Whether There Is in Us a Natural Law?

Objection 1: It would seem that there is no natural law in us.

Because man is governed sufficiently by the eternal law: for

Augustine says (De Lib. Arb. i) that "the eternal law is that by

which it is right that all things should be most orderly." But nature

does not abound in superfluities as neither does she fail in

necessaries. Therefore no law is natural to man.

Obj. 2: Further, by the law man is directed, in his acts, to the end,

as stated above (Q. 90, A. 2). But the directing of human acts to

their end is not a function of nature, as is the case in irrational

creatures, which act for an end solely by their natural appetite;

whereas man acts for an end by his reason and will. Therefore no law

is natural to man.

Obj. 3: Further, the more a man is free, the less is he under the

law. But man is freer than all the animals, on account of his

free-will, with which he is endowed above all other animals. Since

therefore other animals are not subject to a natural law, neither is

man subject to a natural law.

_On the contrary,_ A gloss on Rom. 2:14: "When the Gentiles, who have

not the law, do by nature those things that are of the law," comments

as follows: "Although they have no written law, yet they have the

natural law, whereby each one knows, and is conscious of, what is

good and what is evil."

_I answer that,_ As stated above (Q. 90, A. 1, ad 1), law, being a

rule and measure, can be in a person in two ways: in one way, as in

him that rules and measures; in another way, as in that which is

ruled and measured, since a thing is ruled and measured, in so far as

it partakes of the rule or measure. Wherefore, since all things

subject to Divine providence are ruled and measured by the eternal

law, as was stated above (A. 1); it is evident that all things

partake somewhat of the eternal law, in so far as, namely, from its

being imprinted on them, they derive their respective inclinations to

their proper acts and ends. Now among all others, the rational

creature is subject to Divine providence in the most excellent way,

in so far as it partakes of a share of providence, by being provident

both for itself and for others. Wherefore it has a share of the

Eternal Reason, whereby it has a natural inclination to its proper

act and end: and this participation of the eternal law in the

rational creature is called the natural law. Hence the Psalmist after

saying (Ps. 4:6): "Offer up the sacrifice of justice," as though

someone asked what the works of justice are, adds: "Many say, Who

showeth us good things?" in answer to which question he says: "The

light of Thy countenance, O Lord, is signed upon us": thus implying

that the light of natural reason, whereby we discern what is good and

what is evil, which is the function of the natural law, is nothing

else than an imprint on us of the Divine light. It is therefore

evident that the natural law is nothing else than the rational

creature's participation of the eternal law.

Reply Obj. 1: This argument would hold, if the natural law were

something different from the eternal law: whereas it is nothing but a

participation thereof, as stated above.

Reply Obj. 2: Every act of reason and will in us is based on that

which is according to nature, as stated above (Q. 10, A. 1): for

every act of reasoning is based on principles that are known

naturally, and every act of appetite in respect of the means is

derived from the natural appetite in respect of the last end.

Accordingly the first direction of our acts to their end must needs

be in virtue of the natural law.

Reply Obj. 3: Even irrational animals partake in their own way of the

Eternal Reason, just as the rational creature does. But because the

rational creature partakes thereof in an intellectual and rational

manner, therefore the participation of the eternal law in the

rational creature is properly called a law, since a law is something

pertaining to reason, as stated above (Q. 90, A. 1). Irrational

creatures, however, do not partake thereof in a rational manner,

wherefore there is no participation of the eternal law in them,

except by way of similitude.

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Summa Theologica, Part I-II (Pars Prima Secundae) From the Complete American Edition · 第 589 / 746 题