Is Isidore’s division of human laws
It seems that Isidore proposes an
inappropriate division of human statutes or human law:
Objection 1: Under human
law (ius) he includes the law of nations (ius
gentium), which, as he explains, is so‑called
because nearly all the nations make use of it.
But as he himself says, the natural law is common to
all nations. Therefore, the law of nations is
contained under natural law rather than under positive
Things that have the same force seem to differ from one
another only materially and not formally. But statutes (leges),
popular ordinances (plebiscita), senate decrees (senatusconsulta),
etc., all seem to have the same force. Therefore, it
seems that they differ from one another only materially.
But a theory (ars) should not bother with this sort
of distinction, since it could go on ad infinitum.
Therefore, it is inappropriate to make this sort of
division of human laws.
Just as a city has rulers and priests and soldiers, so too
there are other roles men play as well. Therefore, it
seems that just as one posits military law (ius
militare) along with public law (ius publicum),
which covers priests and magistrates, so too one should
posit other types of law that correspond to other roles in
What is per accidens should be left out of
consideration. But it is incidental to law that it is
made by this or that man. Therefore, it is inappropriate
to posit a divisions of human laws by reference to the
names of lawmakers, as for example to call one sort of law
Cornelian law and another sort Falcidian law, etc.
But contrary to this:
The authority of Isidore is sufficient here.
Each thing is divisible per se on the basis of
what is contained in its definition (ratio).
For instance, soul, which is either rational
or non‑rational, is contained in the definition
of animal, and so animal is divided properly
and per se by rational and non‑rational.
By contrast, animal is not properly and per
se divided by white and black, which
lie completely outside of the definition of animal.
Now there are many elements in the definition of human
law, and human law can be properly and per se
divided in accordance with each of them.
First of all, as was explained above (a. 2), it is part
of the definition of human law that human law
stems from the law of nature. Accordingly, positive
law (ius positivum) is divided into the law
of nations (ius gentium) and civil law (ius
civile), in keeping with the two modes, explained
above (a. 2), in which something stems from the law
of nature. For things that belong to the law of
nations stem from the law of nature as conclusions
from principles—e.g., justice in buying and selling,
etc., in the absence of which men would be unable to
live together with one another. This belongs
to the natural law, since as Politics 1
shows, man is by nature a social animal. On the
other hand, things that stem from the law of nature
in the manner of particular specifications belong
to civil law, according to which each community determines
what is fitting for itself.
Second, it is part of the definition of human law
that human law is ordered toward the common good of
the community. Accordingly, human law can be divided
by the diversity of roles played by those who work specifically
for the common good—e.g., priests, who pray to
God on behalf of the people; rulers, who govern
the people; and soldiers, who fight for the safety
of the people. And so special laws are adapted
to these men as such.
Third, as was explained above (q. 90, a. 3), it is part
of the definition of human law that human is
instituted by one who governs the civil community.
Accordingly, human laws are divided by the diverse forms
of civil government (regimina). One of
these forms, according to the Philosopher in Politics
3, is the kingdom (regnum), viz., when
the community is governed by one man, and, accordingly,
this regime gives rise to the Princely Constitutions.
Another form of government is the aristocracy,
i.e., rule by the best or by the party of the best (optimates),
and, accordingly, this regime gives rise to the Counsels
of the Wise (Responsa Prudentum) and also the
Senate Decrees (Senatusconsulta). The next
form of government is the oligarchy, i.e., rule
by a few rich and powerful men, and, accordingly, this
regime gives rise to the Praetorian Law (Ius Praetorium),
which is also called the Law of Honor (Ius Honararium).
Another form of government is government by the people,
which goes by the name democrary, and, accordingly,
this regime gives rise to Popular Ordinances (plebiscita).
The last form of government is tyranny, which
is altogether corrupt and hence it does not give rise
to any sort of law. There is also a mixed form
of government—the best form—and, accordingly, this regime
gives rise to a type of law which, as Isidore puts it,
has been sanctioned by the elders along with the common
Fourth, it is part
of the definition of human law that it directs
human acts. Accordingly, laws are divided by the
diverse acts about which laws are made. Sometimes
these laws are named after their authors, e.g., the
Julian law concerns acts of adultery, the Cornelian
law concerns assassination, and so on—the laws are distinguished
in this way not because of their authors, but because
of the deeds the acts they are concerned with.
Reply to objection 1:
The law of nations is, to be sure, in some sense natural
to man insofar as he is rational, since it stems from the
natural law in the manner of a conclusion that is not very
far removed from its principles. Hence, it was easy for
men to agree to a law of this sort. However, the law of
nations is nonetheless distinct from the natural law,
especially from what is common to all animals.
Reply to objection 2 and objection 3
and objection 4: The
replies to the other objections are clear from what has