It is common to hear discussions of whether something is moral or immoral, as if “moral” were a word with a specific, agreed-upon meaning. Unfortunately, the word has so many meanings that its interpretation is extremely difficult without extra information. For example, if I say “murder is immoral”, I could actually mean any of the following:
1. Murder violates an abstract principle that I would like all people to live by.
2. The Bible (or some other religious text) forbids murder.
3. As a result of evolution and natural selection, most people have an innate emotional “moral” aversion towards murder.
4. Murder is against the law.
5. Murder is labeled as “immoral” by most people in my society.
6. Murder usually reduces the total net happiness of society.
7. The idea of murder provokes in me a morality-related emotional state of “wrongness”.
8. Nearly all philosophies forbid murder or say it should be avoided.
9. Nearly all societies have laws that punish murderers or have customs that ostracize them.
10. Most people would feel a sense of guilt if they committed murder.
Unfortunately, dictionaries cannot clarify for us what the word “moral” means. For instance, one dictionary defines “moral” as “conforming to a standard of right behavior”. Looking up the relevant definition of “right”, we find “being in accordance with what is just, good, or proper”. But the definition given for “good” is just as vague and circular as were the definitions for “moral” and “right”. Checking another definition, the result is no better. It defines “moral” as “conforming to accepted standards of behavior.” Accepted by whom, and for what reason? The dictionary does not answer these questions, and hence does not provide us with an unambiguous explanation of what “moral” means.
Many well-respected philosophers begin by assuming that morality is a single, well-defined thing and argue about what properties it must have. But if we haven’t defined morality, how can we derive its properties? Are we even talking about the same thing as each other – if we’re not, then of course we can’t agree on the properties of that thing. As the list of interpretations above shows, there are many very different things that we might reasonably call “morality”, including our genetic moral intuitions created by natural selection, the societal rules that are deeply ingrained in us, religious laws, and certain abstract concepts about how to treat each other.
Some people claim that whenever someone says that an action is “moral”, all that person is doing is expressing a feeling or emotion about that action. It’s easily falsified that this is ALL that talk of “morality” is doing – Christians, Kantians, and Utilitarians at least sometimes use the word “moral” to refer to actions that are compatible with biblical teachings, the categorical imperative, and the happiness principle, respectively. These individuals likely have an emotional feeling that their systems of ethics are worthwhile, but nonetheless, they often speak of morality in direct reference to their philosophical systems, independent of their personal feelings. Many people who speak about what is moral at least genuinely believe themselves to be expressing a fact.
Ultimately, before we can decide whether a statement like “murder is immoral” is true, we must first decide what we mean by “moral”. When we don’t know the definition of a word, it is difficult to have a meaningful discussion that relies on it. If we decide that morality is simply whatever the law says, or is determined by what the Bible says, or is a genetic characteristic of human beings, then the question of whether “murder is immoral” becomes an empirical and factual one. We need only check the laws for our country, or search through the Bible, or study human genetics and behavior in order to answer questions about what is moral.
In practice, though, typically when statements about morality are made, there is rarely any explicit or even implicit definition of morality being used. Your average person relies on an intuitive sense of what is right and wrong. This intuitive sense is influenced by many factors, including our genetics, the standards of the society that we live in, the religion that we practice, our personal experiences, and the philosophies that appeal to us. Unfortunately, it appears as though questions about morality are usually unanswerable without further specification about the sense in which “moral” is being used.
If the argument made thus far is true, then how can we understand the fact that nearly everyone seems to agree when it comes to certain ethical statements? For example, how can we account for the fact that almost all people in most of the societies that have ever existed have believed that most kinds of murder are immoral? Well, one relevant factor may be that a strong predisposition to viewing as bad the maurder of close others (especially the murder of family members) is inherent in the human genetic code. More generally, our sense of what is morally wrong appears to be strongly correlated with what we feel an emotional revulsion towards, and those things that we find repulsive are influenced by our genetics. If most humans share a “moral feeling” that is caused by the genes that we share in common, then that provides a plausible explanation of why, for example, murder is generally thought to be immoral.
It is not difficult to imagine that when pre-humans lived in groups, an aversion towards certain types of murder could increase an individual’s chance of survival (perhaps because would-be murderers had a high chance of being killed by their intended victim or the victim’s family). If this were the case, then the process of natural selection could help make a revulsion towards murder a common trait among our ancestors. It may be illuminating to note that many types of carnivores, though feeding daily on other (typically smaller) species, very rarely kill members of their own species (even during fights that break out). This is likely due, at least in part, to the fact that members of a single species are usually fairly evenly matched in strength and fighting skills.
A lion is very unlikely to be killed attempting to kill an antelope. Still, he is fairly likely to be killed or seriously injured when attempting to kill another lion, so lions that focus on eating antelope rather than killing other lions may tend to pass down their genes more effectively (even though there are obvious reasons why one lion might benefit if it does manage to kill another). What’s more, social species may ostracize the members of their group who they feel threatened by, which could dramatically reduce the chance of survival for a “murderer” (by which, in this context, I mean a creature that kills members of its own species). A “moral feeling” would be one possible way, among many, that our genes could urge us not to kill members of our own species.
Another reason for the high convergence in moral views about murder being bad may simply be due to the act itself – it is one that, on nearly any moral view, is bad. But different moral theories, while agreeing on its badness, disagree on why it’s bad and what exactly counts as murder. For instance, they may disagree about whether killing someone in self-defense is murder, or as part of war, or as a punishment for a serious crime.
It’s hard to make progress when discussing moral questions when people mean very different things by “moral,” which, very often, they do.
This piece was first written on July 22, 2009, and first appeared on my website on February 10, 2026.
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