Is morality objective or subjective? Is Christianity credible? Is there evidence for a creator?
According to C. S. Lewis, the law of human nature points to something extraordinary. In Mere Christianity, one of his major arguments for the credibility of Christianity is that morality is objective, universal, and non-material. Furthermore, he argues that these qualities provide evidence for the existence of a creator.
Continue reading to learn the philosophy of C. S. Lewis on the law of human nature.
C. S. Lewis on the Law of Human Nature
According to C. S. Lewis, the law of human nature provides clues about the highest realities. We’ll take a closer look at his case for each of his claims in sequence.
Claim #1: Morality Is Objective and Universal
Lewis argues that morality is not something people invented, but, rather, is objective and universal—much like scientific claims about the material world. He pushes back against the idea that morals are something we decide for ourselves and are therefore malleable. Instead, he argues, morality is a fixed and universal truth, and we cannot simply declare what is right and wrong based on our own changing whims. He marshals two key pieces of evidence to support his perspective: Morality is objective because societies all have shared moral standards, and morality is universal because these standards remain remarkably consistent across cultures.
Moral Laws Are Objective
Lewis argues that morality is objective by pointing out that people quarrel by appealing to shared moral standards. For example, if someone accuses another of treating them unfairly, the accused will rarely defend themselves by rejecting fairness as a standard. Instead, they assert that their behavior didn’t violate this standard or that their situation merited an exception. These tendencies reveal that societies have widely agreed-upon moral laws. Lewis argues that the widespread adoption of single standards of morality suggests that moral codes are real and not simply invented.
Moral Laws Are Universal
Lewis argues that morality is universal by pointing out that every culture has a standard of conduct that members expect each other to uphold. While specific morals may change between cultures, having morals does not. Consider the similarities to language: While cultures have different words for things, there is no culture without a language. Therefore, people invented words, but no one invented language itself. Similarly, no one invented morality.
Furthermore, Lewis argues that moral laws across cultures don’t actually vary that much. There are no moral systems that praise selfishness over selflessness, or that celebrate murder as an inherent good. This suggests that not only did no one invent the idea of morality itself, but that no one invented our core moral tenets either.
|The Philosophical Tradition of Natural Law|
Lewis’s arguments about the objective nature of morality places him in a philosophical tradition called natural law, in which right and wrong are part of the natural order of the world. While its origins might be even older, many scholars trace this idea back to Aristotle, who distinguished actions that were “just by law” from those “just by nature”—in other words, morality can, and does, exist independently of human laws.
The theologian St. Augustine incorporated natural law into Christian belief. He argued that God inscribed an “eternal law” in our minds through the act of creation. Therefore even non-Christians are able to intuit God’s moral principles. Lewis draws on St. Augustine’s version of natural law theory when he cites the similarity of moral laws across cultures.
The theologian Thomas Aquinas built on St. Augustine’s understanding of natural law, arguing that the full extent of the eternal law is known only to God. However, people could come to know more about God’s eternal law by using reason. Though this view stands in tension with the religious belief that morality could only be known through divinely revealed decrees, such as the Ten Commandments, it aligns with Lewis’s arguments that the veracity of Christianity can be deduced through reason.
Claim #2: Morality Is Non-Material
Lewis argues that, in addition to being objective and universal, morality has no material existence. Moral laws are distinct from the material world in that you can’t point to them in the world of things around us or observe them the way you would material phenomena like gravity. Lewis makes three arguments for the non-material nature of morality.
Argument #1: Moral Laws Require Choice
Lewis argues that moral laws are non-material because, even though they are objective, you still must choose to follow them. This makes them distinct from other objective laws, like those of physics. When the law of gravity compels a skydiver to fall to the ground, they can’t choose to disobey. Lewis asserts that moral laws require choice because every society has people who disobey them. Thus, they’re not automatic like the law of gravity.
|Do We Choose to Follow Moral Laws Freely?|
In arguing that we must choose to follow moral laws, Lewis implicitly stakes out a position on the argument between determinism and free will. Philosophers have debated this issue for millennia across several continents. In general, determinists maintain that humans are not free to choose their own actions, because their actions are determined by other forces such as physiological processes in the brain, social pressures, or—in older cosmologies—fate. On the other hand, defenders of free will highlight the subjective experience of making decisions. They also argue—as Lewis does here, and as we’ll see more of later in this guide—that choice is a precondition for morality, and without free will, morality would lose its meaning.
This debate often cleaves along religious lines, with scientific materialists on the side of determinism and religious thinkers on the side of free will. However, there are some interesting exceptions: The atheist philosopher Jean-Paul Sartre argued that humans have complete freedom of choice—whether they want it or not. Meanwhile, a small minority of Christian thinkers have adopted a rare position called hard theological determinism—in which it is impossible for anyone to act against God’s will. Therefore, they contend, we can’t actually choose our own actions.
Argument #2: Moral Laws Cannot Be Observed Through Behavior
Lewis argues that you can’t tell a society’s moral codes simply by viewing people from the outside: You would be able to tell how people act, but not how they believed they ought to act. Instead, understanding moral codes requires understanding how people think. Therefore, moral laws do not exist in an observable, material sense.
(Shortform note: By arguing that moral laws cannot be observed, Lewis is drawing on the “is-ought” distinction, typically associated with the 18th-century philosopher David Hume. Hume contends that you cannot arrive at an understanding of how things ought to be simply by observing how they are. Ethical philosophers argue that failing to recognize this distinction often leads to a status quo bias—that is, people assume that how things are is how they ought to be.)
Argument #3: Moral Laws Cannot be Derived From the Material World
Lastly, Lewis argues that you cannot derive a moral principle from the material world. Rather, you can only derive a moral principle from other moral principles. Every ought statement presupposes another ought statement.
For example, let’s say you want to argue that someone ought to give charity to the poor. You could argue that it would benefit society, but then you still have to explain why someone ought to benefit society. If you argue that someone ought to benefit society because it will improve people’s quality of life, then you still then need to explain why someone ought to improve people’s quality of life, and so on. You cannot cite scientific or mathematical proof for why you ought to do good things. Therefore, Lewis argues, morality does not exist in the material world, even though it is objective.
|Is There a Non-Material World?|
In arguing that morals aren’t part of the material world, Lewis aligns himself with a philosophy of mind called substance dualism (not to be confused with theological dualism, which Lewis discusses below). Substance dualists believe that there are two distinct categories or domains of existence: the material and the non-material. They hold that things that exist in our minds such as values, perceptions, and concepts exist independently of matter. As evidence for their position, substance dualists argue that subjective first-person experiences cannot be described in material scientific terms such as mass, volume, or force.
Critics of dualism—sometimes called monists or materialists—argue that there is no non-material category of existence. They assert that your thoughts, values, and perceptions are instead manifestations of the physical processes of the brain. Therefore your subjective, internal experiences are part of the material world. Advocates support their claims by showing how the mind can be impacted by physical changes to the brain such as injuries or psychoactive chemicals.
Claim #3: Objective, Non-Material Morality Provides Evidence of a Creator
Finally, Lewis argues that the existence of objective, universal, non-material moral laws provides evidence of a creator. He arrives at this conclusion by drawing together three points.
- If moral laws are objective and exist outside of us, then they must have been created by something that is greater than humans.
- If moral laws are non-material and can only be understood by the mind, then the force that created them is likely to have something like a mind itself. A being without a mind wouldn’t be able to create moral laws that can only be experienced in the mind.
- If the moral laws urge us to strive for good over evil, then the creator of these laws likely also prefers good over evil. This suggests the creator of the moral laws also has a will or an intention. Intention also points toward a creator with something like a mind or consciousness.
If we are placed under moral laws beyond our control, then something must have put us in that position. That “something” understands the non-material world of our minds and prefers good over evil. Thus, Lewis argues, we are placed under moral laws by a powerful entity with some form of moral consciousness.
|Understanding What Makes a “Mind”|
Lewis argues that God must have something like a mind because creation includes intangible things like values and moral laws. But how do we understand the “mind” of something without a material presence? According to psychologists, people rely on two characteristics when deciding if something has a “mind.”
Agency: the ability to act and make changes in one’s environment
Experience: the ability to sense and perceive one’s environment
Surveys show that people do not think that God has “experiences” the same way humans do. However, these same surveys show that people believe God has exceptional agency. This comports with Lewis’s explanation of a non-material mind. By creating moral laws for humans to follow, God exercises agency over the world by determining what is right and wrong.
———End of Preview———
Like what you just read? Read the rest of the world's best book summary and analysis of C. S. Lewis's "Mere Christianity" at Shortform.
Here's what you'll find in our full Mere Christianity summary:
- A look at the objective nature of morality
- What it means to surrender yourself to God's moral law
- What Christ means to Christian practice and how to follow his example