The Nature of Natural Law
Mortimer J. Adler
[date of publication not known]
Let us first be clear that by "natural law" we mean
principles of human conduct, not the laws of nature discovered by
the physical sciences. Many thinkers who espouse natural law see it
at work in both the human and nonhuman realms, but their main
interest is in its special application to man. According to these
thinkers, the natural law as applied to physical things or animals
is inviolable; stars and atoms never disobey the laws of their
nature. But man often violates the moral rules which constitute the
law of his specifically human nature.
The idea of a natural right order to which all things, including
human beings, should conform is one of the most ancient and
universal notions. It is a major principle in the religious and
philosophic systems of ancient India and China, as well as in
classical Greek philosophy. Plato calls it "justice" and
applies it to the human soul and human conduct.
In Western society, especially from the Roman jurists and the
theologians of the Middle Age on, we find the doctrine of the
natural moral law for man. It is the source of moral standards, the
basis of moral judgments, and the measure of justice in the man-made
laws of the state. If the law of the state runs counter to the
precepts of the natural law, it is held to be unjust.
The first precept of natural law is to seek the good and avoid
evil. It is often put as follows: "Do good unto others, injure
no one, render to every man his own." Now, of course, such a
general principle is useless for organized society unless we can use
it to specify various types of rights and wrongs. That is precisely
what man-made, or positive, law tries to do.
Thus, the natural law tells us only that stealing is wrong because
it inflicts injury, but the positive law of larceny defines the
various kinds and degrees of theft and prescribes the punishments
Such particular determinations may differ in various times and
places without affecting the principles of natural law. Neither
Aquinas nor Aristotle thinks that particular rules of laws should be
the same in different times, places, and conditions.
You may ask how the natural law is known. Through human reason and
conscience, answer the natural-law thinkers. The natural-law
doctrine usually assumes that man has a specific nature which
involves certain natural needs, and the power of reason to recognize
what is really good for man in terms of these needs.
Christian thinkers, such as Aquinas and John Locke, think the
natural law is of divine origin. God, in creating each thing,
implanted in it the law of its nature. The phrase about "the
laws of nature and of nature's God" in our Declaration of
Independence derives from this type of natural-law doctrine.
However, this particular theological viewpoint is not always found
in writers who uphold the natural law, for these include such
pre-Christian thinkers as Plato, Aristotle, and Cicero, and such
modern secular philosophers as Kant and Hegel.
There has been much opposition to natural-law philosophy from the
very beginning. Indeed, one might say the opposition came first, for
the idea of natural right or justice was developed in ancient Greece
to counter the views of the Sophists, who were "conventionalists."
These men believe that law and justice are simply man-made
conventions. No action is right or wrong unless a particular
community, through its positive laws or customs, decrees that it is
right or wrong. Then it is right or wrong in that particular place
and time -- not universally. By nature, the Sophists say, fire burns
in Greece as it does in Persia, but the laws of Persia and of
Greece, being matters of convention, are not the same. The "conventionalist"
or "positivist" doctrine of law has come down all the way
from the ancient Sophists to many of our modern law-school
You ask whether natural law is relevant to modern conditions. My
answer is that if justice is still relevant, then natural law is.
Indeed, interest in natural law has increased especially during the
past half century, with its experience of the kind of positive laws
which have been imposed by totalitarian regimes. On what grounds
could a decent German citizen in Nazi times justify his opposition
to the laws of the land? On private sentiments or merely personal
opinion? Even purely inner resistance to iniquity must be rooted in
firmer grounds. "A law which is not just is a law in name only,"
says Augustine. And Aquinas adds: "Every human law has just so
much of the nature of law as it is derived from the law of nature.
But if in any point it departs from the law of nature, it is no
longer a law but a perversion of the law."
The naturalists, as that name indicates, affirm the existence of
natural justice, of natural and unalienable rights, of the natural
moral law, and of valid prescriptive oughts that elicit our assent,
both independently of and prior to the existence of positive law.
The positivists deny all this and affirm the opposite. For them, the
positive law -- the man-made law of the state -- provides the only
prescriptive oughts that human beings are compelled to obey.
According to them, nothing is just or unjust until it has been
declared so by a command or prohibition of positive law.
If this is a fundamentally erroneous view, as I think it is, its
ultimate roots lie very deep. They rise from the most profound
mistake that can be made in our thinking about good and evil. It is
the mistake made by those who embrace an unattenuated subjectivism
and relativism with respect to what is good and bad, right and
Neglecting or rejecting the distinction between real and apparent
goods, together with that between natural needs and acquired wants,
the positivists can find no basis for the distinction between what "ought"
to be desired or done and what is desired or done. From that flows
the further consequence that there is no natural moral law, no
natural rights, no natural justice, ending up with the conclusion
that man-made law alone determines what is just and unjust, right
This positivist view is as ancient as the despotisms that existed
in antiquity. It was first eloquently expressed in the opening book
of Plato's "Republic" where Thrasymachus, responding to
Socrates' mention of the view that justice consists in rendering
what is due, declared and defended the opposite view -- that justice
is the interest of the stronger. Spelled out, this means that what
is just or unjust is determined solely by whoever has the power to
lay down the law of the land.
The positivist view is recurrent in later centuries with the
recurrence of later despotisms. It was expressed by the Roman
jurisconsult, Ulpian, who, defending the absolutism of the Caesars,
declared that whatever pleases the prince has the force of law.
Still later, in the sixteenth century, the same view was set forth
by another defender of absolute government, Thomas Hobbes, in "The
Leviathan"; and later, in the nineteenth century, by John
Austin, in his "Analytical Jurisprudence."
Neither Austin nor the twentieth-century legal positivists who
follow him regard themselves as defenders of absolute government or
despotism. That is what they are, however -- perhaps not as
explicitly as their predecessors, but by implication at least. The
denial of natural rights, the natural moral law, and natural justice
leads not only to the positivist conclusion that man made law alone
determines what is just and unjust. It also leads to a corollary
which inexorably attaches itself to that conclusion -- "that
might makes right" -- this is the very essence of absolute or