creature might superfi cially look like a man, but
he would have to be either a beast or a god. It is
important to see in this example from Aristotle a
crucial element associated with natural law the-
ory: An observed or hypothetical difference that
departs from what is regarded as the “natural”
order/law/pattern is not interpreted as an alterna-
tive choice made by a being with a shared nature
(i.e., two men making different choices, but nei-
ther choice makes the chooser any less a man), but
is, instead, interpreted as indicative of a different
nature (i.e., man in contrast to beast or god). In
the medieval period, Thomas Aquinas (1224–74)
continued the natural law tradition in a manner
that synthesized classical teachings and Christian
doctrine. Aquinas taught that God’s reason was
manifest in what humans could understand as
laws of nature.
Modern writers, like English philosophers John
Locke (1632–1704) and William Blackstone
(1723–80), offered elaborate theories based on
natural law, and both Locke and Blackstone infl u-
enced many American thinkers on matters relating
to natural law, natural rights, individualism, the
right of revolution, and the need for limited gov-
ernment. Locke argued that laws of nature were
simply “rules of reason” (i.e., principles that could
be deduced by rational human beings); specifi cally,
Locke asserted that rational people could fi gure
out for themselves three common-sense rules to
live by: Take care of yourself; do not harm others;
and assist others in taking care of themselves when
doing so does not impose self-harm. Governments
did not need to indoctrinate such rules, Locke con-
cluded. Blackstone concurred, noting that the laws
of nature “are performed in a wondrous involun-
tary manner” insofar as they truly do come natu-
rally to rational people. Locke explicitly linked the
concept of natural law with advocacy of limited
government and the right of revolution.
According to Locke, people had the capacity
for knowing natural law (by virtue of their capac-
ity to reason) on their own, and, therefore, in most
instances, governments should be limited to the
role of “umpirage,” that is, stepping in to resolve
disputes when confl ict arose but then immediately
stepping back and leaving rational people alone to
live as they choose within the rules of reason/nat-
ural law. What if government exceeds its bounds
as umpire and violates the laws of nature? Locke’s
answer was both philosophically logical and politi-
cally radical: If the government rebels against
nature/the laws of nature, it is the people’s right to
resist/revolt against the government.
The writings of John Locke and William Black-
stone, as well as their theories of natural law, were of
tremendous infl uence on the constitutional framers.
Thomas Jefferson, for example, invoked Locke
and natural law in the writing of the Declaration
of Independence. Similarly, the idea of natural law
was behind the idea of a bill of rights, with many of
the fi rst 10 amendments representing basic rights
many thought were natural or God-given. In par-
ticular, the Ninth Amendment, which states that
the “enumeration in the Constitution, of certain
rights, shall not be construed to deny or disparage
others retained by the people,” clearly recognized
that individuals had a list of natural rights that the
government could not restrict.
Throughout American history, the concept of
natural law was important in constitutional
interpretation. The idea of natural rights sup-
ported the concepts of economic or substan-
tive due process in the late 19th and early 20th
centuries, as the Supreme Court invoked these
doctrines to limit the ability of state and federal
governments to interfere with the economic rights
of individuals and corporations. Since the New
Deal, natural law, while not explicitly invoked, is
behind many of the claims to protect individual
rights, such as those guaranteeing privacy. Most
recently, Justice Clarence Thomas has invoked
natural law in his constitutional interpretation.
For more information: Blackstone, William.
Commentaries on the Laws of England. Chicago:
The University of Chicago Press, 1979; Locke,
John. “Second Treatise of Government.” In Clas-
sics of Moral and Political Theory. 4th ed. Cam-
bridge, Mass.: Hackett Publishing Company,
2005; Wright, B. F., Jr. “American Interpretations
of Natural Law.” The American Political Science
Review 20 (1926): 524–547.
—Ellen Grigsby
502 natural law
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