J.L. Mackie’s argument from relativity is an argument against moral realism. Or, to frame it the other way round, it’s an argument for moral anti-realism.
In other words, it’s an argument that there are no such things as objective moral properties like ‘good’ and ‘bad’ and ‘right’ and ‘wrong’. And also, that there are no such things as moral facts, like ‘stealing is wrong’. According to Mackie and anti-realism, notions of ‘good’ and ‘bad’ are – at best – something that exist only in our minds. Morality isn’t ‘real’ in any objective or mind-independent way.
The argument, in short, says that this view – moral anti-realism – is the best or simplest explanation for why there are different moral beliefs and practices between cultures.
Moral disagreement
The starting point of Mackie’s argument from relativity is the simple observation that moral codes differ between cultures (and also the same culture at different points in time).
“The argument from relativity has as its premiss the well-known variation in moral codes from one society to another and from one period to another, and also the differences in moral beliefs between different groups and classes within a complex community. Such variation is in itself merely a truth of descriptive morality, a fact of anthropology which entails neither first order nor second order ethical views.”
– J.L. Mackie: Ethics: Inventing Right and Wrong (chapter 1, section 8)
For example:
- Some cultures are monogamous and think polygamy is wrong, whereas other cultures are polygamous.
- In some cultures, eating animals is considered morally wrong, in others it isn’t.
- Back in Plato’s day, it was considered morally acceptable to keep slaves, but in today’s society it isn’t.
So how do we explain these differences?
Two possible explanations
Metaethical positions can be divided into two broad camps:
- Moral realism: Objective, mind-independent moral properties exist.
- Moral anti-realism: Objective, mind-independent moral properties do not exist.
As mentioned, Mackie is firmly in the anti-realist camp. More specifically, he’s an error theorist – but his argument from relativity supports moral anti-realism in general.
His argument is that option 2 – moral anti-realism – is a better explanation of the kinds of moral disagreement described above than option 1.
Explanation 1: Moral realism (morality is discovered)
The moral realist believes in objective moral properties and objective moral facts. And so, for the moral realist, moral disagreement is similar to scientific disagreement.
For example, in the past, most people (wrongly) believed the Sun revolved around the Earth. Eventually, through better observation and reasoning, we discovered the ‘objective truth’ that the Earth revolves around the Sun.
The realist suggests that when two cultures disagree on a moral issue (like polygamy or slavery), it’s a similar situation: One culture is ‘wrong’ about the objective moral facts and the other culture is ‘right’.
But this explanation seems strange – why would one culture manage to perceive these supposed moral truths while others remain blind to them?
With scientific beliefs, the disagreement is usually resolved by new empirical evidence or better technology that eventually leads to a universal consensus. But moral disagreements persist for centuries despite both sides having access to the same facts.
Explanation 2: Moral anti-realism (morality is created)
The other explanation is that there are no objective moral values and facts. This is what moral anti-realism and Mackie say.
On this anti-realist view, neither culture is ‘correct’ about whether polygamy is right or wrong because there is no objective answer. Instead, the differences views on this issue just reflect different values created by different cultures.
“Disagreement about moral codes seems to reflect people’s adherence to and participation in different ways of life. The causal connection seems to be mainly that way round: it is that people approve of monogamy because they participate in a monogamous way of life rather than that they participate in a monogamous way of life because they approve of monogamy.”
– J.L. Mackie: Ethics: Inventing Right and Wrong (chapter 1, section 8)
Instead of, for example, the polygamous culture failing to see a hidden objective truth, Mackie suggests that moral beliefs are simply reflections of how people live.
People in monogamous cultures don’t practice monogamy because they ‘discovered’ an objective moral fact that ‘monogamy is good’. They think monogamy is good because they happen to live in a society where that is the established way of life. If they lived in a different society with different social structures, they would likely hold different moral views.
In other words, morality is a social creation rather than a set of mind-independent facts that are discovered.
An abductive argument
“In short, the argument from relativity has some force simply because the actual variations in the moral codes are more readily explained by the hypothesis that they reflect ways of life than by the hypothesis that they express perceptions, most of them seriously inadequate and badly distorted, of objective values.”
– J.L. Mackie: Ethics: Inventing Right and Wrong (chapter 1, section 8)
Mackie’s argument from relativity is an example of abductive reasoning – i.e. an appeal to the best or most likely explanation.
So Mackie isn’t claiming the argument from relativity proves moral realism is false. Instead, he’s arguing that explanation 2 – i.e. moral anti-realism – is likely to be true because it is a more plausible explanation of the facts than explanation 1 – i.e. moral realism:
- ✅ Explanation 2 (moral anti-realism): Moral disagreement is exactly what we would expect if moral values are not objective, but are instead created by different cultures. If different societies are inventing their own rules to suit their specific way of life, it’s highly likely they would make up different rules and reach different conclusions.
- ❌ Explanation 1 (moral realism): The moral realist has to say that some cultures have – for some unexplained reason – somehow discovered the objective moral truth, while other cultures have – for some unexplained reason – remained morally blind to it.
So, in conclusion, Mackie says moral anti-realism is likely to be true because it is the best explanation of moral disagreement.
The philosophy textbook written in plain English!