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MPA 8300
Leadership Ethics






Overview of Natural Law Theory:




















































































































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"...there is in nature a common principle of the just and unjust
that all people in some way divine [i.e., discern],
even if they have no association or commerce with each other."
(Aristotle, 1991, On Rhetoric I:13:102)


Although Aristotle is oftentimes cited as the philosopher who first described the concept of a natural law―the assertion that there is a natural order to the human world, that this order is good, and that people ought therefore not violate it―it actually was the 4th-century b.c.e. playwright Sophocles who, in Antigone, wrote first about an immutable and eternal law.  In the play, Antigone testifies to Creon that the principles of natural law are rooted in Nature and knowable by the power of reason.  He says: "These laws are not for now or for yesterday, they are alive forever; and no one knows when they were shown to us first" (1973, pp. 38-39).

Three centuries later, the Roman orator and statesman Marcus Tullius Cicero articulated the concept of natural law more forcibly.  In his Laws, Cicero described "Law" as "the highest reason, implanted in Nature, which commands what ought to be done and forbids the opposite" (as cited in Morris, 1959, p. 44).  In addition, Cicero noted that “right is based, not upon men's opinions, but upon Nature” (p. 45).

Much of what is known today about natural law, however, was codified by St. Thomas Aquinas in the 13th century c.e.

In Question 94 of the Prima secundae of his Summa theologiae (I.ii), Aquinas asserted the concept of an eternal law which provides the road map for all ethics and ethical conduct.  This eternal law, Aquinas reasoned, is God's device to govern the entire community of the universe toward the common good.  The divine law, as represented for example in the Ten Commandments, makes eternal law more concrete and knowable.  Natural law then transforms the laws emanating from the realm of the supernatural, making them knowable “in the hearts of human beings” and instruct them “to do good and avoid evil.”  Lastly, human law—which translates natural law into concrete norms governing particular peoples and nations—is the most concrete and specific application of eternal law in the realm of the nature.

This hierarchical structure of law, where the supernatural trumps the natural and the higher order trumps the lower order, is represented in Figure 1.

     Figure 1. The hierarchical structure of law.

                                                                                                     Eternal law
                                   the realm of the supernatural                         

                                                                                                      Divine law
                          ----------------------------          ------- ↕ -------

                                                                                                    Natural law
                                        the realm of the natural                              

Human law

In the realm of the natural, human beings possess the freedom of will to act in or out of accordance with eternal and divine law.  For theists, conformity to eternal and divine law as these are evident in the dictates of natural law brings about happiness while, for non-theists, conformity to natural law alone brings about happiness.  Conversely, nonconformity with natural law results in unhappiness for both theists and non-theists.

Since the time of Thomas Aquinas, natural law has provided the theological rationale implicit in much of the Roman Catholic Church’s moral teaching and, because of this, natural law is oftentimes erroneously believed to be a Roman Catholic “dogma.”  In fact, natural law theory is not Church dogma and has proven influential particularly American jurisprudence, especially as the nation's Founding Fathers envisioned it.  For example, Goebel has noted that Alexander Hamilton “maintained a lifelong belief in a divinely ordained eternal law....[Hamilton wrote] 'No tribunal, no codes, no systems can repeal or impair this law of God, for his eternal laws it is inherent in the nature of things' ” (1964, pp. 821, 838).  Likewise, George Mason used the concept of natural law in Robin v. Hardaway (1772) to contest a State of Virginia slavery statute.  Mason argued:

All acts of legislature apparently contrary to natural right and just are, in our laws, and must be in the nature of things, considered as void.  The laws of nature are the laws of God; Whose authority can be superseded by no power on earth.  A legislature must not obstruct our obedience to him from whose punishments they cannot protect us.  All human constitutions which contradict his laws, we are in conscience bound to disobey.  Such have been the adjudications of our courts of Justice.

While it is accurate to state that the Constitution of the United States is “the supreme law of the land” (US Constitution, VI:2), because the Constitution is based upon the natural law, even the articles of the Constitution and its amendmentsas human laws—are subject to divine and eternal law.  As Rice (1995) comments, if this were not the case, judges would be incapable of overturning duly-ratified constitutional amendments that violated natural, divine, or eternal law.  Rice argues: Suppose, for example, a constitutional amendment was adopted that required disenfranchising persons of certain races or religion.  Would jurists be bound to uphold the amendment and, if they were not, what would they appeal to as a more supreme law (p. 102)?  In terms of statutorial law, like the Civil Rights Act of 1964, what allows one law forbidding segregation to trump other laws upholding segregation?  Simply that they are better, more enlightened laws?  Certainly not.  A more supreme law, divine and eternal law, forbids denying the fundamental equality of human beings.  For that reason alone, human lawslike the Civil Rights Act of 1964trump human laws that violate divine and eternal law (p. 82).  Otherwise, the laws enacted by the Nazi regime and other totalitarian regimes like that of the Ayatollah Khomeini in Iran, regardless of their content, were valid because they were duly enacted (pp. 78-79).

Enlightenment and post-Enlightenment ethicists reject the realm of the supernatural, upon which Aquinas' hierarchical structure depends.  Instead, these ethicists deal only with the realm of the natural, some accepting the idea of a natural law while most reject it, contending that all law is a mere human invention.  In an extreme, these ethicists reject objective standards of goodness, leaving human beings to decide subjectively what constitutes the good or the bad.

Despite its critics, the fact that natural law theory has persisted for so many centuries provides sufficient reason to consider what natural law theory may have to contribute to contemporary discourse about ethics.

The Natural Law...

Although natural law is not “written” in the sense that human laws are codified, it is knowable and binding by nature.  That is, natural law manifests itself to human reason not by any external sign but by a rationally conducted examination of human nature with all its parts and relations.  In this sense, natural law is “virtual” because it exists in every human being even before one’s power of reason is sufficiently developed to form actual ethical judgments.

One of the oldest recorded definitions of natural law comes from the Roman orator, Cicero.  He asserted that natural law is

….right reason in agreement with nature, of universal application, unchanging and everlasting….There will not be a different law at Rome and at Athens, and different law now and in the future, but one eternal and unchangeable law for all nations and for all times. (1928, 3.33)


Rather than utilizing the customs and laws of a particular society as a standard for determining ethical conduct, natural law theory asserts that all human beings by their nature seek happiness and this standard defines conduct as intrinsically ethical and other conduct as intrinsically unethical.  Human beings are “hot wired” for happiness, goal-driven beings inclined toward the good.  Plato and Aristotle understood happiness to be a good pursued solely for its own sake as an end, not a means to another end.  The converse is also true, namely, that humans are “hot wired” to avoid unhappiness.  Hence the similarity between natural law and the aphorism, “Do good and avoid evil,” which some have identified as "the natural law."

A general paradigm explicating the content of the natural law exhibits the following seven elements:

  1. the natural law is naturally knowable by all human beings;

  2. the natural law is knowable by the power of reason;

  3. the natural law is naturally authoritative over all human beings;

  4. the good is prior to the right;

  5. right conduct is action that responds nondefectively to the good;

  6. there are a variety of ways in which conduct can be defective with respect to the good (i.e., intention, circumstance, situation); and,

  7. some of these ways can be captured and formulated as general rules.

This paradigm hinges, of course, upon the notion that human beings possess a common nature and similarity in physiological constitution which makes human beings possess some desires in common and these desires may be so central to human aims and purposes that human beings can build important and correct precepts of rationality around them (e.g., each human being when properly biologically functioning aims to avoid a violent death).  Thus, natural law asserts that ethical conduct is not subjectively defined but is perfective or completing of nature, where what is perfective or completing of nature depends upon its nature (i.e., what is good for an acorn to completely and perfectively be an oak tree differs from what is good for a dog is to completely and perfectively be a dog).  Thus, what is good for a human being is to completely and perfectly be a human being depends upon the kind of thing a human being is by nature.

The idea here is that human beings can derive from a metaphysical study of human nature and its potentialities and actualizations the conclusion that certain things are good for human beings.  Thus,  the primary precepts of the natural law bid and oblige human beings to pursue these things.  Ethicists have argued the following should be included as the goods:

  • life

  • truth and knowledge of it

  • physical and mental health

  • procreation

  • practical reasonableness

  • aesthetic value

  • social life

  • authenticity

  • excellence in work and play

  • theoretical and practical knowledge

  • justice

  • friendship and community

  • rational conduct

  • integrity

  • self-integration and inner peace

  • pleasure and the avoidance of pain


When human beings focus upon their role as recipients of the natural law, the natural law constitutes the principles of practical rationality by which human conduct is to be judged as reasonable or unreasonable.  What each of the goods listed above requires in terms of ethical conduct is not specifically dictated by natural law.  It is, rather, grasped only by a virtuous, practically wise person.

Natural Law and Ethical Decision Making...

Building upon this foundation, natural law theory argues that once the power of reason has determined what is necessary (the “good”), it requires or legislates those actions which promote one’s well being and forbids or proscribes those actions which do not promote happiness.  Because human beings are primarily rational beings and, by virtue of this fact, can intellectually know what is good and willfully choose it by using the power of reason to reflect upon what one’s physical, psychological, and rational needs, it is possible for a person to perfect oneself and attain well-being, happiness, perfection, or what Maslow (1943) called “self‑actualization.”

Notice that the decision‑making process implied by natural law theory emphasizes the mind’s power while denigrating the role of emotions and feelings.  In legislating conduct that human beings must perform and must avoid, the power of reason translates eternal ideas about truth, justice, goodness, beauty, and the like into virtuous conduct that human beings are obliged to enact.  In this sense, then, the power of reason functions as a noninfallible “law giver.” 

Many actions are ethically good in and of themselves or, at least, are ethically indifferent, including: helping the poor and destitute, marital sex, bearing and rearing children, intellectual, aesthetic, and kinesthetic pursuits, as well as the exchange of goods and services in the marketplace.  Other actions which do not promote achievement of the good must be shunned.  Murder, suicide, theft, lying, and rape are examples of such intrinsically unethical conduct that natural law theory asserts no human being may ever commit no matter how many good consequences might result from performing acts these and similar acts.

This obligation to pursue the good and to avoid evil is neither specific to any culture nor is it time bound.  Instead, this obligation extends to all people everywhere and at all times because of the common nature shared by all human beings.  Natural law is, as it were, constitutive of human nature.

While some philosophers have called natural law theory “absolutist” and, in its strict application it is absolutist, the theory does highlight some rather important aspects of the ethical decision‑making process.

One aspect is the notion that it is not enough simply to conduct oneself according to the dictates of natural law.  What is also significant is the intention behind the action; it must also be good.  That is, one can perform a good act with an evil intention; such conduct is ethically wrong because it condones evil and reveals one’s character to be unethical.  For example, it is unethical to tell someone the truth with the explicit intent of causing harm to that person.

Another aspect of ethical decision making natural law theory illuminates is how circumstances are crucial to the ethical decision-making process.  They can transform an action that otherwise is ethical into an unethical action.  For example, sexual relations are good in themselves but not with someone who is not a spouse or of the same gender.

Lastly, while the consequences of conduct oftentimes are important for deciding what does or does not contribute to one’s well-being, happiness, or perfection, natural law theory maintains that the consequences do not provide the ultimate criterion for determining whether an action is ethical or not.  Conduct that produces unethical effects at all times and in all circumstances is “unnatural” because it violates nature’s essential tendency toward preserving itself.  The effects of conduct, then, by themselves do not make the action unethical; they demonstrate that the act is unnatural and that characteristic, in and of itself, makes the conduct unethical.  For example, the natural end of sexual relations is self‑preservation as well as the preservation of the human species through the procreative act.  When sexual relations cannot fulfill this natural end as, for example, in the conduct of homosexual relations as well as the conduct of sexual relations where an unnatural means is introduced to impede the possibility of procreation, this conduct is unnatural and this characteristic alone is what makes these and other similar actions unethical.

Opponents of Natural Law Theory...

As might be expected by the applications of natural law theory cited above, it has come under heavy fire, especially in recent decades, and for a variety of reasons.

Some have vociferously argued that there is no such thing as a “natural law.”  Instead, these individuals and groups argue that it is a hypothesis or intellectual invention intended to proscribe conduct that those hypothesizing or inventing the theory want to impose unilaterally upon others.  Advocates of homosexual rights, for example, assert that sexual relations are good in themselves and that this applies not just to those who have entered into marriages sanctioned by civil law but also to those who are not married yet love one another.  Some feminists have also argued against natural law.  These persons insist that natural law provides the rationale used historically to subject women to patriarchal domination under the specious argument that nature determines gender roles.  Interestingly, antagonism toward natural law theory joins military theorists with homosexual rights advocates as well as some feminists.  These theorists find the strict application of the natural law untenable because it forbids the killing of innocent civilians even if the conduct promises to save many lives.  In developing military plans, the goal is to minimize "collateral damage," especially the number of noncombatant deaths.  That noncombatants will die as a consequence of military action is presumed.

Another argument advanced against natural law theory is that many things that are in one sense or another unnatural aren’t believed by most people to be unethical.  Take, for example, vaccinations, anesthesia, shaving, and chemotherapy.  There are also many things that are, in one sense or another natural, yet many people believe are unethical.  Examples include: revenge, prejudice, or rubbing one’s eye when there is something in it.  Consider the situation confronting an emergency room physician:  if she fails to restore the natural functioning of the human being―which requires doing something unnatural―by fixing a broken arm or to correct for a dietary deficiency causing diarrhea, she would seemingly be violating the natural law.  Likewise, if a dermatologist fails to provide hair transplants, even to those who believe they will be miserable without the transplants, the dermatologist does not violate the natural law.

To remedy for situations where conduct might cause both good and evil effects, natural law theorists invoke the principle of double effect.

In sum...

Natural law, then, is promulgated to human beings through the power of reason and the content of the natural law is knowable.  Sufficiently normal and mature human beings know the general principles implied by the natural law, but deductions about what the law and its principles mean in concrete circumstances are not as clear.  Different conclusions and applications can be derived by equally wise people.  Thus, a diversity of opinion exists about what the natural law requires in actual practice and is a matter not of theoretical or abstract wisdom but of practical wisdom by which human beings discern what ought to be their conduct in particular circumstance as the seek to do good and avoid evil.


Aquinas, T.  (1991).  Summa theologiae: A concise translation (T. McDermott, Trans.).  Allen, TX: Christian Classics.

Aristotle.  (1991).  On rhetoric (G. A. Kennedy, Trans.)  Oxford, UK: Oxford University Press.

Cicero. (1928).  The republic (De republica). (C. W. Keyes, Trans. and Ed.).  London: Loeb Classical Library.

Maslow, A. H.  (1943).  A theory of human motivation.  Psychological Review, 50, 370‑396.

Morris, C. (Ed.).  (1959).  Great legal philosophers: Selected readings in jurisprudence.  Philadelphia, PA: University of Pennsylvania Press.

Rice, C.  (1993).  50 questions on the natural law: What it is and why we need it.  San Francisco, CA: Ignatius Press.

Robin v. Hardaway, 2 Va. (2 Jefferson) 109, 114 (1772).

Sophocles.  (1973).  Antigone (R. E. Braun, Trans.).  Oxford, UK: Oxford University Press.