Natural Law

Natural Law Theory proposes that as physical laws of nature exist, so do universal moral laws. These laws disclose themselves to us upon close examination of the world and the nature of humans. Aspects of natural law theory date back to Plato, who posited the existence of transcendental “Forms” (Plato, 1992). Particular instances of these forms – such as the Good, the True, and the Beautiful – are reflected in human life. To “see” the form of the Good (to have a clear idea of it) and incarnate it in one’s deeds is both a cause and consequence of wisdom. While Plato alluded to what we today refer to as “natural law,” the Stoics developed the theory more fully. The Stoics claim the order of the universe is fundamentally rational. Human rationality, therefore, is a person’s innate moral compass. To reason and act rationally is to be in harmony with the universe. Violence and vice are consequences of irrationality and not being in harmony with universal laws.


St. Thomas Aquinas

If natural law is born of the Greeks, it comes of age with the Roman Catholic Church. Perhaps the most famous of natural law theorists is St. Thomas Aquinas (1225-1274). According to Aquinas’s theology, natural law is integral to divine providence. “Eternal law” is the overarching law, established by God, which gives order to the chaos of creation. The portion of eternal law pertaining to human beings is, to Aquinas, natural law. Unlike other natural bodies (earth and animals for instance), humans are not determined by natural law.  Instead, God has instilled in us our sense of rationality. With this reason we apprehend and participate in His eternal law if we so choose.  Like the Stoics, then, Aquinas thinks that lucid reasoning is the means by which to discern universal moral truth and, by acting in accordance with it, fulfill our destinies (Stanford Encyclopedia of Philosophy, 2002).

Objections to Theory

There are two main objections to Natural Law Theory, both raised during the Enlightenment period (17th and 18thcenturies). The first, advanced by Scottish philosopher David Hume (1711-1776), is that Natural Law Theory conflates that which is the case with that which ought to be the case. One cannot, as Hume pointed out, logically derive a moral imperative or value judgment simply by observing facts of nature. Natural Law theorists often argue, for example, that because God’s laws (and laws of nature in this case) dictate the purpose of sexual intercourse is reproduction, it is unnatural and thus, immoral to have sex for any other purpose. The fallaciousness of this reasoning is especially obvious when we consider natural tendencies which, are seemingly irreconcilable with ethical behavior. For example, if one concedes that it is natural for human beings to care for themselves before strangers, then one must also accept that this ought to be the case (Rachels, 2007: 60-61).

The second argument against Natural Law Theory is the theory’s assumption that moral principles are written in the laws of nature (or by God). Modern science contradicts this assumption. The scientific perspective sees only cause and effect in the natural world; morals and values, it claims, are inventions of the human mind. From this worldview, the continued use of Natural Law Theory in the Catholic Church (where it is most prominent) is a holdover from Medieval thought (Rachels, 2007: 61).

Response to Objections

In response to arguments from science, the Church may defer to the maxim “absence of evidence is not evidence of absence.” In other words, it does not necessarily follow that if science cannot detect moral laws in the natural world, then they do not in fact exist. Though it would be a fallacy still to conclude that they do exist because their inexistence cannot be proven (known as the “Argument from Ignorance”), this argument opens room for faith, with which the Church is ultimately concerned.

Natural Law Theory Today

Due to these arguments against it, Natural Law Theory plays virtually no role in contemporary secular moral discourse (Rachels, 2007: 60). However, devout Christians number in the hundreds of millions in the world today and the Protestant and Catholic Churches are significant players in almost every country’s moral discourse.  Thus, knowledge of Natural Law Theory is necessary to engage with and understand the traditional Christian position.


References Cited

Plato (1992) Republic. Hackett Publishing Company, Inc. Indianapolis

Rachels, James (2007) The Elements of Moral Philosophy. The McGraw-Hill Companies

Stanford Encyclopedia of Philosophy (2002) The Natural Law Tradition in Ethics

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