I believe that one source of confusion can be solved by the distinction between normative and descriptive ethics. Whenever people talk about cultural relativism or evolutionary theories of ethics, I think they have descriptive ethics in mind, but they often jump to the conclusion that whatever they are talking about has certain obvious normative implications. In particular, some people claim that morality comes from evolution and others claim that morality is relative. What they have in mind often doesn’t actually make sense, as I will discuss in detail.
Normative and descriptive ethics
Normative ethics is about intrinsic value, right and wrong, and/or virtues. The following are claims concerning normative ethics:
It is wrong to kill people just because they make you angry.
We should fight to free slaves when necessary, even when doing so is illegal.
Pain is intrinsically bad—we ought not cause pain without a good reason to do so.
It is reasonable for a person to give charity to those in need, even if no reciprocation should be expected.
Normative ethics is thought to have overriding importance for determining how we ought to act. Even if you want a million dollars, you ought not kill innocent people in order to get a million dollars in return. Etiquette is often said to be similar to normative ethics, except etiquette is not of overriding importance. Burping is considered to be rude, but it is not that big of a deal.
Descriptive ethics is about what motivates pro-social behavior, how people reason about ethics, what people believe to have overriding importance, and how societies regulate behavior (such as by punishing people for doing certain actions). We know that empathy helps motivate pro-social behavior (such as giving to charity) and we know that our beliefs about what has overriding importance is somewhat based on the culture we live in.
What behaviors are punished in a society tells us something about what the people find to be of overriding importance, and the type of punishment I have in mind is basically just negative consequences. Punishment could even be social pressure, such as being criticized for doing something unethical. For example, Jonathan Haidt has talked about the importance of gossip and reputation for motivating ethical behavior. (See “New Synthesis in Moral Psychology” (PDF).)
There are certain predictable ways people reason about ethics (often in unreasonable ways). For example, people often overestimate the importance of consequences when considering how well reasoned people’s moral decisions are. (See information about the outcome bias (PDF).)
Evolution and ethics
People often claim that morality comes from evolution. I agree that we evolved an ability to reason about ethics, we evolved certain pro-social intuitions, and we evolved empathy. Scientists can explain quite a bit about why people often act ethically (in pro-social ways) and sometimes act unethically. That’s descriptive ethics.
I think it is clear that evolution and science in general has a lot to tell us about descriptive ethics, but what about normative ethics? Does evolution tell us that we ought not cause nonhuman animals needless suffering? Not everyone seems to have much empathy for nonhuman animals and I suspect we evolved that way precisely to make it easier for people to hunt nonhuman animals for food. I see no obvious way to jump from the results we get concerning descriptive ethics to reach conclusions concerning normative ethics. For example, it would be fallacious to think that anyone who didn’t evolve an automatic empathetic response towards nonhuman animals would therefore have no reason to care about the well being of nonhuman animals. (See this for more information.)
Some people might think evolution (and other scientific facts) somehow explain away normative ethics—perhaps every belief we have about right and wrong are actually false. Maybe we reason about morality and have empathy because that’s how we evolved, but there are no moral facts. That could be right, but obviously much more would need to be said. We can’t just assume that normative ethics should be rejected without argument. I think we do think we know certain things about normative ethics and it would not be appropriate to throw out those beliefs without a good reason.
Anthropologists have reported that different cultures have different moral beliefs (as did Herodotus thousands of years ago). It isn’t a big leap to realize that people’s beliefs about ethics have something to do with their cultural upbringing. This is sometimes described as “descriptive cultural relativism.” It is nothing more than the claim that our moral beliefs are influenced by our culture and that people of different cultures often disagree about certain moral issues. For example, some cultures think young girls should be circumcised and other cultures think it is child abuse.
However, the term “cultural relativism” tends to actually refer to “normative cultural relativism.” That view states that what is actually right or wrong is based on the culture we are in – whatever a culture says is right or wrong is true for that culture. In that case slavery might not be wrong for all people (because many people seemed to genuinely think it was ethical in the past) and it might not be unethical to cause nonhuman animals needless suffering for all people.
Some people have argued that morality is relative (with normative ethics in mind) by explaining how different cultures have different views about morality, but that argument doesn’t work. We can’t rationally jump to that conclusion about normative ethics by merely knowing that our moral beliefs are influenced by our culture.
How could anyone take normative cultural relativism seriously? Why think that “murder is wrong” is true for us only because your culture says it is wrong? The fact that cultures have different moral beliefs doesn’t guarantee that all cultures have true ethical beliefs.
I think that people have been confused and jump to strange conclusions because they have not properly differentiated normative and descriptive ethics. Some people seem to think that how we evolved can somehow tell us what we should believe about normative ethics, but our pro-social tendencies are actually a topic for descriptive ethics. Some people seem to think that morality is relative (in a normative sense), and people often argue for that position by talking about how descriptive ethics is relative (because different cultures have different views about ethics). I don’t think that their argument makes sense.
The Definition of Morality (Stanford Encyclopedia of Philosophy)
Morality and Evolutionary Biology (Stanford Encyclopedia of Philosophy)
Evolutionary Ethics (Internet Encyclopedia of Philosophy)