Error theory is a theory about morality that makes the following claims.
(1) Moral statements are statements that make a claim of “objective intrinsic prescriptivity." These are claims that some actions contain an intrinsic property of ought-to-be-doneness or ought-not-to-be-doneness that is the source of our moral obligations and prohibitions.
(2) Objective intrinsic prescriptivity does not exist.
From this, it concludes that all moral claims are false (or errors).
Desirism accepts Proposition 2.
This essay concerns Proposition 1. Is it true that our moral language contains a claim of objective, intrinsic prescriptivity? If so, what are the implications of this for morality in general and for desirism in specific?
The answer will be: It is probably not true and, even if it is true, it would have little importance. J. L. Mackie himself, the philosopher who developed error theory, provides us with easy-to-follow instructions for a low-cost way of dealing with the problem that all moral claims are false. I will look at his suggestion after considering two ways in which we can reject Proposition 1.
Response 1: The Objective Intrinsic Prescriptivity Hypothesis Is False
The claim that moral terms contain, as a part of their meaning, a reference to objective, intrinsic prescriptivity is a hypothesis meant to explain a set of observed facts about how moral terms are used. In this case, the set of observations particularly relevant in supporting the objective intrinsic prescriptivity hypothesis are those where claims about the rightness and wrongness of some action implies that other moral agents - even non-human agents - are supposed to perform or avoid those actions.
However, there is a significant problem with the Objective Intrinsic Prescriptivity hypothesis. No such property exists.
Yet, people use moral terms as if they are talking about something that is both real and important. They use moral claims as justification for inflicting real costs - real punishments, including death - on other human beings.
Many of the things that people talk about turn out not to be real - even where people believe that they are real. However, a hypothesis that says that all of the statements in a general category of discussion are false should not be our first guess. If we have more than one interpretation available to us, we should go with the interpretation that allows those claims to be true unless compelled to select another option.
An alternative interpretation says that whether some act is obligatory, permissible, or wrong can best be understood as claims about actions that people generally have many and strong reasons to praise (or to condemn the refusal to act), have little reason to praise or condemn, or have reason to condemn (or praise the refusal to act) respectively.
These reasons to act are other desires. The reason to praise or condemn are reasons to apply reward and punishment to the reward systems of other brains to promote desires that tend to fulfill other desires, and inhibit desires that tend to thwart other desires.
Desirism proposes that this is a better hypothesis because it better explains a wide range of phenomena associated with moral statements such the use of praise and condemnation in moral claims (to mold malleable desires), the logic of excuse claims (to deny that an act type is one that people have any reason to condemn), the moral concept of negligence (condemning the absense of a sufficiently strong aversion to causing harm to others), and “ought” implies “can” (it makes no sense to use praise and condemnatin where no malleable desires are involved).
Furthermore, it allows for some moral claims to be true - which itself is more consistent with the way that people actually use these terms.
If we compare the strengths of each hypothesis in allowing us to understand the elements of our moral life, desirism has far more explanatory power than the objective, intrinsic prescriptivity hypothesis and, as a result, is a better theory about how moral terms are actually being used.
This would imply that Proposition 1 is false and we can reject error theory.
Response 2: Pluralistic Moral Reductionism. We have No Common Moral Language
Another approach we can take to Proposition 1 is to deny that moral terms actually have a common meaning. This is the approach taken by Luke Meuhlhauser in a view he calls "pluralistic moral reductionism".
Pluralistic moral reductionism looks at the way that languages are learned and concludes that it is highly unlikely that there is a common meaning to moral terms. Languages are learned through experience. Each of us has a variety of experiences, meaning that each of us has a slightly different understanding of many common terms. Moral terms do not have a fixed definition. Rather, they are a set of fuzzy concepts that generally have something to do with getting people to perform or refrain from certain actions. As fuzzy concepts, any attempt to find a fixed and universal meaning will fail.
In the case of moral terms, this problem is compounded by the fact that the meanings of moral terms are theory-laden. Merely adopting a moral theory itself involves accepting a set of definitions - a set that would not be consistent with the set adopted by somebody else who adopts a different theory. Some people have adopted a theory that says that some actions contain intrinsic prescriptivity. Others speak of moral terms as if they mean, "I approve of a state in which everybody does X." Every utilitarian, divine command theorist, prescriptivist, emotivist, Kantian, Objectivist, and the like has adopted their own moral language.
Adopting a language does not entitle a person to their own facts. A person who adopts a divine command theory adopts a language where all moral claims are false. Furthermore, the fact that those claims are false does not change the material fact that there are malleable desires that people generally have many and strong reasons to promote or inhibit using social forces such as praise and condemnation. Who people can adopt all of the same facts, yet report those facts using different languages. It is inconvenient, but not impossible.
If there is no common moral language, then Proposition 1, which assumes a common languagem can be rejected.
Response 3: Mackie's Moral Revisionism
Response 3 accepts Proposition 1, but says that we can easily navigate around the problem.
Mackie himself argued that the fact that we have built a false assumption into the meaning of our moral terms is not a major crisis. We can easily remove that false assumption and continue to work with what is left. This would allow us to make true value claims in such a way that even many of our previous claims can be interpreted in such a way that they are true.
To illustrate what he was talking about, Mackie used the example of the word ‘atom’. Originally, the word ‘atom’ meant ‘uncuttable’. An atom, then, was defines as the smallest bit of matter that could not be reduced into smaller bits.
The term ‘atom’ came to be used to refer to the smallest particle of an element such as carbon, oxygen, or gold.
Eventually, scientists started to suspect that these smallest particles of an element could be split. They had parts: electrons, protons, and neutrons.
Chemists could keep 'without parts' as a part of the definition of ‘atom’ and deny that these things they have been talking about are atoms (since they had parts). Or they could change the definition, drop ‘without parts’ from the meaning, and continue to claim that these smallest pieces of an element were atoms. Many previous papers and findings about atoms would still hold true. The only difference is that we would drop the implication that those previous papers were talking about things that could not be split. That error was not relevant to the claims made in those papers anyway.
Mackie argued that we should do the same with moral terms. Wr can drop ‘objective intrinsic prescriptivity’ from its meaning and go ahead and continue to make moral claims. We would no longer infer that wrongness implied an intrinsic property but, instead, argue that it referred to something that tended to have a negative impact on people’s interests or desires. This lead him to a form of utilitarianism, which he went on to apply to issues such as abortion and euthanasia to yield what he implied were objectively true moral claims.
Chemistry went through its revision painlessly. Science has gone through a great many revisions without trauma. "Malaria" went from meaning "bad air" to a disease typically spread by mosquitoes. "Water" went from "a common colorless, tasteless liquid that living things needed to consume in abundance" to "H2O". The term "planet" went from "wandering star" to "something large orbiting a sun but not so large that it generates energy through fusion".
Chemistry is filled with revisions of this type. Lead, gold, and sulphur are all among the terms that have all changed their meaning as chemists tell us more about what we now know to be basic elements. This change has taken place without any great trauma.
Mackie's error theory holds that all moral claims are false because they contain a claim of objective intrinsic prescriptivity that does not exist. We can allow that objective intrinsic prescriptivity does not exist yet still reject Mackie's error theory by denying that this is a part of the meaning of moral terms. We could argue that moral terms have an alternative meaning that does not include this element. Or we can deny that moral terms even have a common meaning.
Yet, even if Mackie is right and moral terms contain this meaning, we can easily deal with this problem. We can do what scientists routinely do - simply redefine our words in such a way that they keep as much of the original meaning as possible while dropping the part that is in error, or adopting a more efficient definition. Scientists practice this form of revisionism constantly without any great difficulties. Ethicists can learn from this example.