QUESTION 90: OF THE ESSENCE OF LAW
We have now to consider the extrinsic principles of acts. Now the
extrinsic principle inclining to evil is the devil, of whose temptations
we have spoken in the FP, Question . But the extrinsic principle moving to
good is God, Who both instructs us by means of His Law, and assists us by
His Grace: wherefore in the first place we must speak of law; in the
second place, of grace.
Concerning law, we must consider: (1) Law itself in general; (2) its
parts. Concerning law in general three points offer themselves for our
consideration: (1) Its essence; (2) The different kinds of law; (3) The
effects of law.
Under the first head there are four points of inquiry:
(1) Whether law is something pertaining to reason?
(2) Concerning the end of law;
(3) Its cause;
(4) The promulgation of law.
Article 1: Whether law is something pertaining to reason?
Objection 1: It would seem that law is not something pertaining to reason. For
the Apostle says (Rm. 7:23): "I see another law in my members," etc. But
nothing pertaining to reason is in the members; since the reason does not
make use of a bodily organ. Therefore law is not something pertaining to
Objection 2: Further, in the reason there is nothing else but power, habit,
and act. But law is not the power itself of reason. In like manner,
neither is it a habit of reason: because the habits of reason are the
intellectual virtues of which we have spoken above (Question ). Nor again is
it an act of reason: because then law would cease, when the act of reason
ceases, for instance, while we are asleep. Therefore law is nothing
pertaining to reason.
Objection 3: Further, the law moves those who are subject to it to act aright.
But it belongs properly to the will to move to act, as is evident from
what has been said above (Question , Article ). Therefore law pertains, not to the
reason, but to the will; according to the words of the Jurist (Lib. i,
ff., De Const. Prin. leg. i): "Whatsoever pleaseth the sovereign, has
force of law."
I answer that, Law is a rule and measure of acts, whereby man is induced
to act or is restrained from acting: for "lex" [law] is derived from
"ligare" [to bind], because it binds one to act. Now the rule and measure
of human acts is the reason, which is the first principle of human acts,
as is evident from what has been stated above (Question , Article , ad 3); since
it belongs to the reason to direct to the end, which is the first
principle in all matters of action, according to the Philosopher (Phys.
ii). Now that which is the principle in any genus, is the rule and
measure of that genus: for instance, unity in the genus of numbers, and
the first movement in the genus of movements. Consequently it follows
that law is something pertaining to reason.
Reply to Objection 1: Since law is a kind of rule and measure, it may be in
something in two ways. First, as in that which measures and rules: and
since this is proper to reason, it follows that, in this way, law is in
the reason alone. Secondly, as in that which is measured and ruled. In
this way, law is in all those things that are inclined to something by
reason of some law: so that any inclination arising from a law, may be
called a law, not essentially but by participation as it were. And thus
the inclination of the members to concupiscence is called "the law of the
Reply to Objection 2: Just as, in external action, we may consider the work and
the work done, for instance the work of building and the house built; so
in the acts of reason, we may consider the act itself of reason, i.e. to
understand and to reason, and something produced by this act. With regard
to the speculative reason, this is first of all the definition; secondly,
the proposition; thirdly, the syllogism or argument. And since also the
practical reason makes use of a syllogism in respect of the work to be
done, as stated above (Question , Article ; Question , Article ) and since as the
Philosopher teaches (Ethic. vii, 3); hence we find in the practical
reason something that holds the same position in regard to operations,
as, in the speculative intellect, the proposition holds in regard to
conclusions. Such like universal propositions of the practical intellect
that are directed to actions have the nature of law. And these
propositions are sometimes under our actual consideration, while
sometimes they are retained in the reason by means of a habit.
Reply to Objection 3: Reason has its power of moving from the will, as stated
above (Question , Article ): for it is due to the fact that one wills the end,
that the reason issues its commands as regards things ordained to the
end. But in order that the volition of what is commanded may have the
nature of law, it needs to be in accord with some rule of reason. And in
this sense is to be understood the saying that the will of the sovereign
has the force of law; otherwise the sovereign's will would savor of
lawlessness rather than of law.
Article 2: Whether the law is always something directed to the common good?
Objection 1: It would seem that the law is not always directed to the common
good as to its end. For it belongs to law to command and to forbid. But
commands are directed to certain individual goods. Therefore the end of
the law is not always the common good.
Objection 2: Further, the law directs man in his actions. But human actions
are concerned with particular matters. Therefore the law is directed to
some particular good.
Objection 3: Further, Isidore says (Etym. v, 3): "If the law is based on
reason, whatever is based on reason will be a law." But reason is the
foundation not only of what is ordained to the common good, but also of
that which is directed private good. Therefore the law is not only
directed to the good of all, but also to the private good of an
On the contrary, Isidore says (Etym. v, 21) that "laws are enacted for
no private profit, but for the common benefit of the citizens."
I answer that, As stated above (Article ), the law belongs to that which is
a principle of human acts, because it is their rule and measure. Now as
reason is a principle of human acts, so in reason itself there is
something which is the principle in respect of all the rest: wherefore to
this principle chiefly and mainly law must needs be referred. Now the
first principle in practical matters, which are the object of the
practical reason, is the last end: and the last end of human life is
bliss or happiness, as stated above (Question , Article ; Question , Article ).
Consequently the law must needs regard principally the relationship to
happiness. Moreover, since every part is ordained to the whole, as
imperfect to perfect; and since one man is a part of the perfect
community, the law must needs regard properly the relationship to
universal happiness. Wherefore the Philosopher, in the above definition
of legal matters mentions both happiness and the body politic: for he
says (Ethic. v, 1) that we call those legal matters "just, which are
adapted to produce and preserve happiness and its parts for the body
politic": since the state is a perfect community, as he says in Polit. i,
Now in every genus, that which belongs to it chiefly is the principle of
the others, and the others belong to that genus in subordination to that
thing: thus fire, which is chief among hot things, is the cause of heat
in mixed bodies, and these are said to be hot in so far as they have a
share of fire. Consequently, since the law is chiefly ordained to the
common good, any other precept in regard to some individual work, must
needs be devoid of the nature of a law, save in so far as it regards the
common good. Therefore every law is ordained to the common good.
Reply to Objection 1: A command denotes an application of a law to matters regulated by the law. Now the order to the common good, at which the law aims, is applicable to particular ends. And in this way commands are given even concerning particular matters.
Reply to Objection 2: Actions are indeed concerned with particular matters: but
those particular matters are referable to the common good, not as to a
common genus or species, but as to a common final cause, according as the
common good is said to be the common end.
Reply to Objection 3: Just as nothing stands firm with regard to the speculative
reason except that which is traced back to the first indemonstrable
principles, so nothing stands firm with regard to the practical reason,
unless it be directed to the last end which is the common good: and
whatever stands to reason in this sense, has the nature of a law.
Article 3: Whether the reason of any man is competent to make laws?
Objection 1: It would seem that the reason of any man is competent to make
laws. For the Apostle says (Rm. 2:14) that "when the Gentiles, who have
not the law, do by nature those things that are of the law . . . they are
a law to themselves." Now he says this of all in general. Therefore
anyone can make a law for himself.
Objection 2: Further, as the Philosopher says (Ethic. ii, 1), "the intention
of the lawgiver is to lead men to virtue." But every man can lead another
to virtue. Therefore the reason of any man is competent to make laws.
Objection 3: Further, just as the sovereign of a state governs the state, so
every father of a family governs his household. But the sovereign of a
state can make laws for the state. Therefore every father of a family can
make laws for his household.
On the contrary, Isidore says (Etym. v, 10): "A law is an ordinance of
the people, whereby something is sanctioned by the Elders together with
I answer that, A law, properly speaking, regards first and foremost the
order to the common good. Now to order anything to the common good,
belongs either to the whole people, or to someone who is the viceregent
of the whole people. And therefore the making of a law belongs either to
the whole people or to a public personage who has care of the whole
people: since in all other matters the directing of anything to the end
concerns him to whom the end belongs.
Reply to Objection 1: As stated above (Article , ad 1), a law is in a person not only
as in one that rules, but also by participation as in one that is ruled.
In the latter way each one is a law to himself, in so far as he shares
the direction that he receives from one who rules him. Hence the same
text goes on: "Who show the work of the law written in their hearts."
Reply to Objection 2: A private person cannot lead another to virtue
efficaciously: for he can only advise, and if his advice be not taken,
it has no coercive power, such as the law should have, in order to prove
an efficacious inducement to virtue, as the Philosopher says (Ethic. x,
9). But this coercive power is vested in the whole people or in some
public personage, to whom it belongs to inflict penalties, as we shall
state further on (Question , Article , ad 3; SS, Question , Article ). Wherefore the
framing of laws belongs to him alone.
Reply to Objection 3: As one man is a part of the household, so a household is a
part of the state: and the state is a perfect community, according to
Polit. i, 1. And therefore, as the good of one man is not the last end,
but is ordained to the common good; so too the good of one household is
ordained to the good of a single state, which is a perfect community.
Consequently he that governs a family, can indeed make certain commands
or ordinances, but not such as to have properly the force of law.
Article 4: Whether promulgation is essential to a law?
Objection 1: It would seem that promulgation is not essential to a law. For
the natural law above all has the character of law. But the natural law
needs no promulgation. Therefore it is not essential to a law that it be
Objection 2: Further, it belongs properly to a law to bind one to do or not to
do something. But the obligation of fulfilling a law touches not only
those in whose presence it is promulgated, but also others. Therefore
promulgation is not essential to a law.
Objection 3: Further, the binding force of a law extends even to the future,
since "laws are binding in matters of the future," as the jurists say
(Cod. 1, tit. De lege et constit. leg. vii). But promulgation concerns
those who are present. Therefore it is not essential to a law.
On the contrary, It is laid down in the Decretals, dist. 4, that "laws
are established when they are promulgated."
I answer that, As stated above (Article ), a law is imposed on others by way
of a rule and measure. Now a rule or measure is imposed by being applied
to those who are to be ruled and measured by it. Wherefore, in order that
a law obtain the binding force which is proper to a law, it must needs be
applied to the men who have to be ruled by it. Such application is made
by its being notified to them by promulgation. Wherefore promulgation is
necessary for the law to obtain its force.
Thus from the four preceding articles, the definition of law may be
gathered; and it is nothing else than an ordinance of reason for the
common good, made by him who has care of the community, and promulgated.
Reply to Objection 1: The natural law is promulgated by the very fact that God
instilled it into man's mind so as to be known by him naturally.
Reply to Objection 2: Those who are not present when a law is promulgated, are
bound to observe the law, in so far as it is notified or can be notified
to them by others, after it has been promulgated.
Reply to Objection 3: The promulgation that takes place now, extends to future
time by reason of the durability of written characters, by which means it
is continually promulgated. Hence Isidore says (Etym. v, 3; ii, 10) that
"lex [law] is derived from legere [to read] because it is written."