QUESTION 94: OF THE NATURAL LAW
We must now consider the natural law; concerning which there are six
points of inquiry:
(1) What is the natural law?
(2) What are the precepts of the natural law?
(3) Whether all acts of virtue are prescribed by the natural law?
(4) Whether the natural law is the same in all?
(5) Whether it is changeable?
(6) Whether it can be abolished from the heart of man?
Article 1: Whether the natural law is a habit?
Objection 1: It would seem that the natural law is a habit. Because, as the
Philosopher says (Ethic. ii, 5), "there are three things in the soul:
power, habit, and passion." But the natural law is not one of the soul's
powers: nor is it one of the passions; as we may see by going through
them one by one. Therefore the natural law is a habit.
Objection 2: Further, Basil [*Damascene, De Fide Orth. iv, 22] says that the
conscience or "synderesis is the law of our mind"; which can only apply
to the natural law. But the "synderesis" is a habit, as was shown in the
FP, Question , Article . Therefore the natural law is a habit.
Objection 3: Further, the natural law abides in man always, as will be shown
further on (Article ). But man's reason, which the law regards, does not
always think about the natural law. Therefore the natural law is not an
act, but a habit.
On the contrary, Augustine says (De Bono Conjug. xxi) that "a habit is
that whereby something is done when necessary." But such is not the
natural law: since it is in infants and in the damned who cannot act by
it. Therefore the natural law is not a habit.
I answer that, A thing may be called a habit in two ways. First, properly and essentially: and thus the natural law is not a habit. For it has been stated above (Question , Article , ad 2) that the natural law is something appointed by reason, just as a proposition is a work of reason. Now that which a man does is not the same as that whereby he does it: for he makes a becoming speech by the habit of grammar. Since then a habit is that by which we act, a law cannot be a habit properly and essentially.
Secondly, the term habit may be applied to that which we hold by a
habit: thus faith may mean that which we hold by faith. And accordingly,
since the precepts of the natural law are sometimes considered by reason
actually, while sometimes they are in the reason only habitually, in this
way the natural law may be called a habit. Thus, in speculative matters,
the indemonstrable principles are not the habit itself whereby we hold
those principles, but are the principles the habit of which we possess.
Reply to Objection 1: The Philosopher proposes there to discover the genus of
virtue; and since it is evident that virtue is a principle of action, he
mentions only those things which are principles of human acts, viz.
powers, habits and passions. But there are other things in the soul
besides these three: there are acts; thus "to will" is in the one that
wills; again, things known are in the knower; moreover its own natural
properties are in the soul, such as immortality and the like.
Reply to Objection 2: "Synderesis" is said to be the law of our mind, because it
is a habit containing the precepts of the natural law, which are the
first principles of human actions.
Reply to Objection 3: This argument proves that the natural law is held
habitually; and this is granted.
To the argument advanced in the contrary sense we reply that sometimes a
man is unable to make use of that which is in him habitually, on account
of some impediment: thus, on account of sleep, a man is unable to use the
habit of science. In like manner, through the deficiency of his age, a
child cannot use the habit of understanding of principles, or the natural
law, which is in him habitually.
Article 2: Whether the natural law contains several precepts, or only one?
Objection 1: It would seem that the natural law contains, not several
precepts, but one only. For law is a kind of precept, as stated above
(Question , Article ). If therefore there were many precepts of the natural law,
it would follow that there are also many natural laws.
Objection 2: Further, the natural law is consequent to human nature. But human
nature, as a whole, is one; though, as to its parts, it is manifold.
Therefore, either there is but one precept of the law of nature, on
account of the unity of nature as a whole; or there are many, by reason
of the number of parts of human nature. The result would be that even
things relating to the inclination of the concupiscible faculty belong to
the natural law.
On the contrary, The precepts of the natural law in man stand in
relation to practical matters, as the first principles to matters of
demonstration. But there are several first indemonstrable principles.
Therefore there are also several precepts of the natural law.
I answer that, As stated above (Question , Article ), the precepts of the
natural law are to the practical reason, what the first principles of
demonstrations are to the speculative reason; because both are
self-evident principles. Now a thing is said to be self-evident in two
ways: first, in itself; secondly, in relation to us. Any proposition is
said to be self-evident in itself, if its predicate is contained in the
notion of the subject: although, to one who knows not the definition of
the subject, it happens that such a proposition is not self-evident. For
instance, this proposition, "Man is a rational being," is, in its very
nature, self-evident, since who says "man," says "a rational being": and
yet to one who knows not what a man is, this proposition is not
self-evident. Hence it is that, as Boethius says (De Hebdom.), certain
axioms or propositions are universally self-evident to all; and such are
those propositions whose terms are known to all, as, "Every whole is
greater than its part," and, "Things equal to one and the same are equal
to one another." But some propositions are self-evident only to the wise,
who understand the meaning of the terms of such propositions: thus to one
who understands that an angel is not a body, it is self-evident that an
angel is not circumscriptively in a place: but this is not evident to the
unlearned, for they cannot grasp it.
Now a certain order is to be found in those things that are apprehended
universally. For that which, before aught else, falls under apprehension,
is "being," the notion of which is included in all things whatsoever a
man apprehends. Wherefore the first indemonstrable principle is that "the
same thing cannot be affirmed and denied at the same time," which is
based on the notion of "being" and "not-being": and on this principle all
others are based, as is stated in Metaph. iv, text. 9. Now as "being" is
the first thing that falls under the apprehension simply, so "good" is
the first thing that falls under the apprehension of the practical
reason, which is directed to action: since every agent acts for an end
under the aspect of good. Consequently the first principle of practical
reason is one founded on the notion of good, viz. that "good is that
which all things seek after." Hence this is the first precept of law,
that "good is to be done and pursued, and evil is to be avoided." All
other precepts of the natural law are based upon this: so that whatever
the practical reason naturally apprehends as man's good (or evil) belongs
to the precepts of the natural law as something to be done or avoided.
Since, however, good has the nature of an end, and evil, the nature of a
contrary, hence it is that all those things to which man has a natural
inclination, are naturally apprehended by reason as being good, and
consequently as objects of pursuit, and their contraries as evil, and
objects of avoidance. Wherefore according to the order of natural
inclinations, is the order of the precepts of the natural law. Because in
man there is first of all an inclination to good in accordance with the
nature which he has in common with all substances: inasmuch as every
substance seeks the preservation of its own being, according to its
nature: and by reason of this inclination, whatever is a means of
preserving human life, and of warding off its obstacles, belongs to the
natural law. Secondly, there is in man an inclination to things that
pertain to him more specially, according to that nature which he has in
common with other animals: and in virtue of this inclination, those
things are said to belong to the natural law, "which nature has taught to
all animals" [*Pandect. Just. I, tit. i], such as sexual intercourse,
education of offspring and so forth. Thirdly, there is in man an
inclination to good, according to the nature of his reason, which nature
is proper to him: thus man has a natural inclination to know the truth
about God, and to live in society: and in this respect, whatever pertains
to this inclination belongs to the natural law; for instance, to shun
ignorance, to avoid offending those among whom one has to live, and other
such things regarding the above inclination.
Reply to Objection 1: All these precepts of the law of nature have the character
of one natural law, inasmuch as they flow from one first precept.
Reply to Objection 2: All the inclinations of any parts whatsoever of human
nature, e.g. of the concupiscible and irascible parts, in so far as they
are ruled by reason, belong to the natural law, and are reduced to one
first precept, as stated above: so that the precepts of the natural law
are many in themselves, but are based on one common foundation.
Reply to Objection 3: Although reason is one in itself, yet it directs all things
regarding man; so that whatever can be ruled by reason, is contained
under the law of reason.
Article 3: Whether all acts of virtue are prescribed by the natural law?
Objection 1: It would seem that not all acts of virtue are prescribed by the
natural law. Because, as stated above (Question , Article ) it is essential to a
law that it be ordained to the common good. But some acts of virtue are
ordained to the private good of the individual, as is evident especially
in regards to acts of temperance. Therefore not all acts of virtue are
the subject of natural law.
Objection 2: Further, every sin is opposed to some virtuous act. If therefore
all acts of virtue are prescribed by the natural law, it seems to follow
that all sins are against nature: whereas this applies to certain special
Objection 3: Further, those things which are according to nature are common
to all. But acts of virtue are not common to all: since a thing is
virtuous in one, and vicious in another. Therefore not all acts of virtue
are prescribed by the natural law.
On the contrary, Damascene says (De Fide Orth. iii, 4) that "virtues are
natural." Therefore virtuous acts also are a subject of the natural law.
I answer that, We may speak of virtuous acts in two ways: first, under
the aspect of virtuous; secondly, as such and such acts considered in
their proper species. If then we speak of acts of virtue, considered as
virtuous, thus all virtuous acts belong to the natural law. For it has
been stated (Article ) that to the natural law belongs everything to which a
man is inclined according to his nature. Now each thing is inclined
naturally to an operation that is suitable to it according to its form:
thus fire is inclined to give heat. Wherefore, since the rational soul is
the proper form of man, there is in every man a natural inclination to
act according to reason: and this is to act according to virtue.
Consequently, considered thus, all acts of virtue are prescribed by the
natural law: since each one's reason naturally dictates to him to act
virtuously. But if we speak of virtuous acts, considered in themselves,
i.e. in their proper species, thus not all virtuous acts are prescribed
by the natural law: for many things are done virtuously, to which nature
does not incline at first; but which, through the inquiry of reason, have
been found by men to be conducive to well-living.
Reply to Objection 1: Temperance is about the natural concupiscences of food,
drink and sexual matters, which are indeed ordained to the natural common
good, just as other matters of law are ordained to the moral common good.
Reply to Objection 2: By human nature we may mean either that which is proper to
man---and in this sense all sins, as being against reason, are also
against nature, as Damascene states (De Fide Orth. ii, 30): or we may
mean that nature which is common to man and other animals; and in this
sense, certain special sins are said to be against nature; thus contrary
to sexual intercourse, which is natural to all animals, is unisexual
lust, which has received the special name of the unnatural crime.
Reply to Objection 3: This argument considers acts in themselves. For it is owing
to the various conditions of men, that certain acts are virtuous for
some, as being proportionate and becoming to them, while they are vicious
for others, as being out of proportion to them.
Article 4: Whether the natural law is the same in all men?
Objection 1: It would seem that the natural law is not the same in all. For it
is stated in the Decretals (Dist. i) that "the natural law is that which
is contained in the Law and the Gospel." But this is not common to all
men; because, as it is written (Rm. 10:16), "all do not obey the gospel."
Therefore the natural law is not the same in all men.
Objection 2: Further, "Things which are according to the law are said to be
just," as stated in Ethic. v. But it is stated in the same book that
nothing is so universally just as not to be subject to change in regard
to some men. Therefore even the natural law is not the same in all men.
Objection 3: Further, as stated above (Articles ,3), to the natural law belongs
everything to which a man is inclined according to his nature. Now
different men are naturally inclined to different things; some to the
desire of pleasures, others to the desire of honors, and other men to
other things. Therefore there is not one natural law for all.
On the contrary, Isidore says (Etym. v, 4): "The natural law is common
to all nations."
I answer that, As stated above (Articles ,3), to the natural law belongs
those things to which a man is inclined naturally: and among these it is
proper to man to be inclined to act according to reason. Now the process
of reason is from the common to the proper, as stated in Phys. i. The
speculative reason, however, is differently situated in this matter, from
the practical reason. For, since the speculative reason is busied chiefly
with the necessary things, which cannot be otherwise than they are, its
proper conclusions, like the universal principles, contain the truth
without fail. The practical reason, on the other hand, is busied with
contingent matters, about which human actions are concerned: and
consequently, although there is necessity in the general principles, the
more we descend to matters of detail, the more frequently we encounter
defects. Accordingly then in speculative matters truth is the same in all
men, both as to principles and as to conclusions: although the truth is
not known to all as regards the conclusions, but only as regards the
principles which are called common notions. But in matters of action,
truth or practical rectitude is not the same for all, as to matters of
detail, but only as to the general principles: and where there is the
same rectitude in matters of detail, it is not equally known to all.
It is therefore evident that, as regards the general principles whether
of speculative or of practical reason, truth or rectitude is the same for
all, and is equally known by all. As to the proper conclusions of the
speculative reason, the truth is the same for all, but is not equally
known to all: thus it is true for all that the three angles of a triangle
are together equal to two right angles, although it is not known to all.
But as to the proper conclusions of the practical reason, neither is the
truth or rectitude the same for all, nor, where it is the same, is it
equally known by all. Thus it is right and true for all to act according
to reason: and from this principle it follows as a proper conclusion,
that goods entrusted to another should be restored to their owner. Now
this is true for the majority of cases: but it may happen in a particular
case that it would be injurious, and therefore unreasonable, to restore
goods held in trust; for instance, if they are claimed for the purpose of
fighting against one's country. And this principle will be found to fail
the more, according as we descend further into detail, e.g. if one were
to say that goods held in trust should be restored with such and such a
guarantee, or in such and such a way; because the greater the number of
conditions added, the greater the number of ways in which the principle
may fail, so that it be not right to restore or not to restore.
Consequently we must say that the natural law, as to general principles,
is the same for all, both as to rectitude and as to knowledge. But as to
certain matters of detail, which are conclusions, as it were, of those
general principles, it is the same for all in the majority of cases, both
as to rectitude and as to knowledge; and yet in some few cases it may
fail, both as to rectitude, by reason of certain obstacles (just as
natures subject to generation and corruption fail in some few cases on
account of some obstacle), and as to knowledge, since in some the reason
is perverted by passion, or evil habit, or an evil disposition of nature;
thus formerly, theft, although it is expressly contrary to the natural
law, was not considered wrong among the Germans, as Julius Caesar relates
(De Bello Gall. vi).
Reply to Objection 1: The meaning of the sentence quoted is not that whatever is
contained in the Law and the Gospel belongs to the natural law, since
they contain many things that are above nature; but that whatever belongs
to the natural law is fully contained in them. Wherefore Gratian, after
saying that "the natural law is what is contained in the Law and the
Gospel," adds at once, by way of example, "by which everyone is commanded
to do to others as he would be done by."
Reply to Objection 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 to Objection 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.
Article 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.
Objection 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 (Gn. 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.
Objection 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 (Article ), 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 (Article ).
Reply to Objection 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.
Reply to Objection 2: All men alike, both guilty and innocent, die the death of
nature: which death of nature is inflicted by the power of God on account
of original sin, according to 1 Kgs. 2:6: "The Lord killeth and maketh
alive." Consequently, by the command of God, death can be inflicted on
any man, guilty or innocent, without any injustice whatever. In like
manner adultery is intercourse with another's wife; who is allotted to
him by the law emanating from God. Consequently intercourse with any
woman, by the command of God, is neither adultery nor fornication. The
same applies to theft, which is the taking of another's property. For
whatever is taken by the command of God, to Whom all things belong, is
not taken against the will of its owner, whereas it is in this that
theft consists. Nor is it only in human things, that whatever is
commanded by God is right; but also in natural things, whatever is done
by God, is, in some way, natural, as stated in the FP, Question , Article , ad 1.
Reply to Objection 3: A thing is said to belong to the natural law in two ways.
First, because nature inclines thereto: e.g. that one should not do harm
to another. Secondly, because nature did not bring in the contrary: thus
we might say that for man to be naked is of the natural law, because
nature did not give him clothes, but art invented them. In this sense,
"the possession of all things in common and universal freedom" are said
to be of the natural law, because, to wit, the distinction of possessions
and slavery were not brought in by nature, but devised by human reason
for the benefit of human life. Accordingly the law of nature was not
changed in this respect, except by addition.
Article 6: Whether the law of nature can be abolished from the heart of man?
Objection 1: It would seem that the natural law can be abolished from the
heart of man. Because on Rm. 2:14, "When the Gentiles who have not the
law," etc. a gloss says that "the law of righteousness, which sin had
blotted out, is graven on the heart of man when he is restored by grace."
But the law of righteousness is the law of nature. Therefore the law of
nature can be blotted out.
Objection 2: Further, the law of grace is more efficacious than the law of
nature. But the law of grace is blotted out by sin. Much more therefore
can the law of nature be blotted out.
Objection 3: Further, that which is established by law is made just. But many
things are enacted by men, which are contrary to the law of nature.
Therefore the law of nature can be abolished from the heart of man.
On the contrary, Augustine says (Confess. ii): "Thy law is written in
the hearts of men, which iniquity itself effaces not." But the law which
is written in men's hearts is the natural law. Therefore the natural law
cannot be blotted out.
I answer that, As stated above (Articles ,5), there belong to the natural
law, first, certain most general precepts, that are known to all; and
secondly, certain secondary and more detailed precepts, which are, as it
were, conclusions following closely from first principles. As to those
general principles, the natural law, in the abstract, can nowise be
blotted out from men's hearts. But it is blotted out in the case of a
particular action, in so far as reason is hindered from applying the
general principle to a particular point of practice, on account of
concupiscence or some other passion, as stated above (Question , Article ). But
as to the other, i.e. the secondary precepts, the natural law can be
blotted out from the human heart, either by evil persuasions, just as in
speculative matters errors occur in respect of necessary conclusions; or
by vicious customs and corrupt habits, as among some men, theft, and even
unnatural vices, as the Apostle states (Rm. i), were not esteemed sinful.
Reply to Objection 1: Sin blots out the law of nature in particular cases, not
universally, except perchance in regard to the secondary precepts of the
natural law, in the way stated above.
Reply to Objection 2: Although grace is more efficacious than nature, yet nature
is more essential to man, and therefore more enduring.
Reply to Objection 3: This argument is true of the secondary precepts of the
natural law, against which some legislators have framed certain
enactments which are unjust.