Charitable Relatives: The Narrow Case for the Argument from Relativity

I will consider whether J.L. Mackie’s argument from relativity should undermine confidence in moral objectivism. First, I will briefly reconstruct the relevant points of Mackie’s argument and gloss some of the terms we will use. Second, I will demonstrate a notable weakness in one of its premises. Third, I will detail the strength I find in the argument as support for other, more direct arguments for moral subjectivism.  Finally, I will conclude that while the argument from relativity is not alone sufficient to undermine confidence in moral objectivism, that goal is beyond the scope of the argument; still, the argument does carry some strength to undermine objectivism in a supplementary sense.

I. The Argument and the Outline

Mackie’s (1977)[1] argument from relativity holds that differences in moral codes across cultures and time are best explained as reflections of groups’ ways of life. He acknowledges that the presence of differences or disagreement is not alone sufficient to disprove the objective nature of a matter. For example, radical differences exist across cultures and time over matters of science, yet we readily accept the objectivity of those matters. The difference, Mackie argues, is that scientific disagreements are based on an exchange of evidence, and he finds it implausible that moral disagreements are so evidenced. Instead, they seem to be born of and reflect differences in various groups’ ways of life. Mackie offers this subjective explanation for moral differences as evidence against an objectivist view (Mackie, 1977).

The main points of Mackie’s (1977) argument from relativity, as I understand it, are outlined below. I have teased out the more minor premises in two and three below because they support Mackie’s concluding inference to the best explanation yet seem to contain a flaw.

1. Groups differentiated socially, culturally, and temporally disagree over moral judgments.
2. Such groups also disagree over matters of science, which we agree are objective in nature.
3. Disagreements over matters of science are based on objective evidence.
4. It is implausible that disagreements over moral judgments are based on objective evidence.
5. Disagreements over moral judgments seem to reflect groups’ ways of life.
6. Therefore, the best explanation for disagreements over moral judgments is that they are based on groups’ ways of life, not on objective evidence like scientific disagreements.

(Mackie, 1977)

Additionally, it is worth clarifying some of the terms I will use in this paper. Mackie (1977) argues against moral realism but hardly uses that term in the subject material for this paper. Instead, he addresses his opposition to the more specific view of moral objectivism. Moral realism, in the simplest terms, is the view that “moral claims can be true or false and some are true” (Sayre-McCord, 2021). Moral objectivism is the view some realists hold that the truth or falsity of a moral claim obtains independent of the agent making the claim (Dancy, 2018). Moral subjectivism, in the broadest sense, is an anti-objectivist view holding that moral facts exist but are agent-dependent (Sayre-McCord, 2021). Mackie argues for an even more specific form of moral subjectivism known as moral error theory, which holds that all moral claims are necessarily untrue because the world lacks any moral “stuff” against which to judge the claims’ truth or falsity (Mackie, 1977; Sayre-McCord, 2021).

II. The Relatively Weak Premise

Mackie (1977) fails to adequately address a potential objection, resulting in a possibly flawed premise three, as enumerated above. He grants that “the mere occurrence of disagreements” does not itself disprove the objectivity of a disputed matter, but he goes on to argue that disagreements over moral judgments are different (p. 36). He acknowledges that disagreement is routinely found in areas of inquiry that we generally agree contain objective facts—namely, fields of science. But disagreements in areas of science, Mackie says, result from “inadequate evidence” and presumably the introduction of new or more robust evidence—an account that he asserts could not plausibly explain moral disagreements (p. 36). In this rapid dismissal, Mackie leaves a narrow gap for the moral objectivist to counter, as I will attempt on their behalf (Mackie, 1977).

I agree with Mackie (1977) in premise four that moral disagreements do not seem to be evidenced by newly observed facts about things in the world, as we often see in scientific literature. However, I find that Mackie fails to entirely escape the objection he is addressing and fails to adequately support premise three. There do seem to be disagreements over matters of science that are not objectively evidenced. We can find a simple counterexample that illustrates this by considering disagreements over what happens when we die. I find it implausible to classify postulates and disputes over the nature or existence of the afterlife as objectively evidenced, given that they concern experiences from which living things are phenomenologically and perceptually isolated. Still, I have no difficulty accepting that there is most certainly an objective answer to the question, in the conscious identity sense, “what happens to us when we die?”

More pertinent counterexamples may be found in early or pre-science beliefs about the world. In many cases, hypotheses and disagreements were bandied about for centuries or more despite their interlocutors having no access to the objective facts of the matter. Consider disagreements over the contents, nuances, or existence of the cellular or atomic world before the advent of microscopy or disagreements over the contents or depths of the deep-sea world before the last 150 years of modern diving technology or even more recent satellite technology. These and similar examples show that it is historically not unusual for differing beliefs about matters of science to arise despite a lack of access to—and inability to offer—the relevant objective evidence. In fact, such disagreement could reasonably be deemed as resulting from a lack of access to the relevant objective evidence. However, in neither sense would we be likely to assert that there is no objective fact of the matter, as Mackie asserts of moral disagreements.

These counterexamples do not overturn Mackie’s argument but considerably weaken its conclusion. A charitable reading would require revising premise three to state, “Disagreements over matters of science are sometimes based on objective evidence.” Based on that reading, objectively evidenced disagreement is perhaps sufficient to prove the objective nature of a given matter, but it is not necessary. More directly, evidence-based disagreement is no more necessary to prove the objective nature of moral judgments than it is to prove the objective nature of matters of pre- and proto-science. Without further argument on this point, which Mackie does not offer, it remains an open possibility that morality—like the afterlife and many early sciences—is an objective matter, the evidence for which we do not yet have access. Because of this open and weak foundation, I do not find that the argument from relativity, taken alone, carries enough weight to undermine confidence in moral objectivism.

III. The Relative Strength of the Argument from Relativity

Despite its failure to independently undermine moral objectivism, I find that Mackie’s (1977) argument from relativity still supports his larger argument in the direction of moral subjectivism. The openness of the question that I noted above applies to both sides of the debate: Neither the argument nor my critique of it closes the case for either objectivity or subjectivity. The narrow utility of the argument that remains is illustrated in the following example. Suppose we encounter two paths while hiking in the woods, and I want to argue that we should take the path on the left. I might support my argument with the observation that no fallen trees or other debris are blocking the path on the left. That is what Mackie’s argument from relativity, weakened by its open foundational premise, does for the larger argument. It is too weak to be independently convincing because, as we can see in both the objectivist/subjectivist argument and my hiking example, the other path is open as well.

The path for which Mackie (1977) argues contains certain features that relate to other arguments for subjectivity to which I am more sympathetic. Most notably, his suggestion that moral codes are reflections of a group’s way of life rather than the other way around. That notion relates to what I perceive in Mackie’s larger argument as support for moral fictionalism. Granted, Mackie concludes with support for an error theory understanding of morality and makes no explicit mention of fictionalism. Still, support for it can be found in several parts of his work. Since fictionalism itself is outside the scope of this paper, I will only briefly regard two such points to support the purpose of this section (Mackie, 1977).

First, earlier in the same chapter, Mackie (1977) paints an excellent example of how scientifically sophisticated individuals who understand that color is not a property possessed of an object but an individual’s perception of certain wavelengths of light reflected by an object will continue to use color language in a scientifically inaccurate way because of its social and heuristic utility. Later in the chapter, he addresses such a utility regarding morality specifically, noting that the use of objective moral language serves the agent’s need to “regulate interpersonal relations” and “control some of the ways in which people behave toward one another” (p. 43). Objective moral language, even if fictional, provides the authority necessary to compel compliance with those standards and expectations (Mackie, 1977).

I raise these points to show that, while the argument from relativity does not alone have the power to undermine confidence in moral objectivism, it at least demonstrates that the door is left open to arguments that—by my lights—do undermine moral objectivism. In other words, the argument has some strength by virtue of its supportive relation to other arguments that I find more directly compelling.

In section two, I addressed Mackie’s failure to adequately secure premise three—the notion that disagreements over matters of science are based on objective evidence. This also represents a failure to adequately escape the objection to which he was responding—that there are other perfectly intelligible examples of broad disagreement over issues that we generally accept as objective in nature. While I do not find that the argument from relativity alone is strong enough to disprove moral objectivism because of flaws like the one addressed here, I also must charitably acknowledge that it does not seem to have been Mackie’s intent to offer an argument with such strength. After all, he begins by framing the argument as only “indirectly support[ing] second order subjectivism” (Mackie, 1977, p. 36).

It would be reasonable to end there, concluding that whether by Mackie’s intention or not, the argument by itself is not strong enough to undermine confidence in moral objectivism. Still, I am sympathetic to an even more charitable conclusion because Mackie does not present the argument from relativity by itself but in a supportive relation to his other more direct arguments against moral objectivism. As I find those arguments compelling, I am inclined to conclude that there is some strength in the argument from relativity in that narrow, supportive sense. That is where I ultimately land. The argument from relativity, construed as support for more direct and compelling arguments favoring moral subjectivism, does help to undermine moral objectivism.

Dancy, J. (2018). Moral realism. Routledge. https://doi.org/10.4324/9780415249126-l059-1

Mackie, J. L. (1977). Ethics. Inventing right and wrong. Penguin Books.

Sayre-McCord, G. (2021). Moral Realism. The Stanford Encyclopedia of Philosophy. Retrieved October 2, 2023, from https://plato.stanford.edu/entries/moral-realism/

[1] Due to the volume of citations, narrative references to Mackie (1977) following an initial in-text citation will omit the publication year per section 8.16 of the APA 7^th Ed. Publication Manual.