Part 2: Arguments for Meta-Ethical Subjective Relativism
Part 3: Meta-Ethical Subjective Relativism in Practice
In part 1, I discussed what meta-ethical subjective relativism (MESR) says:
Statements about ethics have an absolute truth-value if and only if they are stated relative to some subjective entity or property.This formulation can also be termed strong MESR. Weak MESR just replaces "if and only if" with just "if":
Statements about ethics have an absolute truth-value if they are stated relative to some subjective entity or property.
Weak MESR is uncontroversially true: people do in fact have mental states (subjective properties) with ethical content.
The truth of weak MESR allows us to hold strong MESR on a skeptical basis: Absent a compelling argument for an objectivist alternative, weak MESR would entail strong MESR as the only understood way of establishing the truth value of statements with ethical content. If it makes you feel better, you can recast strong MESR as epistemic MESR:
Statements about ethics have an absolute truth-value which can be presently known if and only if they are stated relative to some subjective entity or property.
Thus the task of this essay is to undermine arguments for moral objectivism.
I'm going to talk about objectivism vs. subjectivism instead of relativism and absolutism because it is really the first distinction which critics who condemn "relativism" are addressing. Classical moral realism, for instance, is still "relative" a the trivial sense: An ethical statement under moral realism is true relative to how reality actually is. Critics of "relativism" are, I think, really criticizing holding ethical statements true relative to subjective states.
Moral objectivism entails that there are ethical statements which are true or false stated without implicit or explicit relation to subjective entities and their properties, i.e. minds and states of mind. Moral objectivism does not deny that we can indeed have mental states with ethical content, or that the process of knowing the truth of an ethical statement does not involve subjective participation.
"The earth is (more or less) spherical," is an example of a physical objectivist statement. This statement is truth-apt as it stands, and actually true even if anyone or even everyone were to believe the contrary. It's still objectivist even though people can in fact know it. It is still objectivist even though a person can discover the truth of the statement only by appeal to subjective observational experience. It's even still objectively true even though it is stated in a natural language: the concepts of "earth" and "round" are not joined in one's subjective language processing.
I want to set a low bar for moral objectivism, at least as low as for objective physical reality. Even set this low, however, there is a strong epistemic argument that we cannot know if any moral statement is objectively true.
In The Scientific Method, I discuss various epistemic bases for knowledge about objective physical reality: axiomatic foundationalism, coherentism, and evidentiary foundationalism. Like Goldilocks, we have to exclude the first two: axiomatic foundationalism is too narrow and coherentism is too broad; the third, evidentiary foundationalism is just right.
Axiomatic foundationalism holds that we somehow establish the absolute perfect truth of some premises, after which we know that all of our logical deductions will preserve the truth of those premises. Because we have to construct perfectly axioms without even a good basis, Axiomatic Foundationalism fails as a fundamental epistemic method.
Coherentism (as best I can determine) holds that we gain knowledge merely by keeping our belief system coherent, that is avoiding mutually contradictory beliefs. Coherentism seems to be too broad, with many internally coherent but mutually contradictory belief systems that would satisfy its criteria.
So the evidentiary foundationalism of the scientific method would seem to be our last resort. It works for science, why not for ethics?
Evidentiary foundationalism needs uncontroversial statements to act as an evidentiary foundation. But ethical philosophy by its nature is about controversial statements. We don't need an ethical system to determine what everyone agrees upon, we need it to solve disagreements. We need laws against theft because thieves do not agree that stealing (at least their own) is wrong. We need laws against murder because murderers do not agree that killing is wrong.
Another feature of perceptual statements as an evidentiary foundation is that they are occasion statements: an individual speaker will assent on some occasions and dissent on others. Moral intuitions, on the other hand, are typically standing sentences: speakers typically always assent or dissent. The fact that multiple speakers consistently assent or dissent to occasion statements argues directly that their mutual assent is caused by an objective reality. No such direct argument can exist for standing sentences.
We could just exclude such dissenters; we do, after all, exclude people (e.g. schitzophrenics) from scientific discourse on their inability to assent to perceptual facts. But only a tiny fraction of people are excluded on their inability to see light and dark bands in a diffraction pattern compared to those who are skeptical (or were in the 1920's) about the Schroedinger wave equation.
Essentially, standing moral intuitions talk about exactly the same sort of thing that we want an ethical system to prove. An "objective" morality which by definition proves with everything we already think is not useful. In science, we are not trying to prove that that the rock will fall--we already know that rocks fall--we want to discover why they fall. An ethical system that depends on moral intuition for evidence cannot, by definition, ever contradict our moral intuition.
Another problem with both axiomatic and evidentiary foundationalism is that both tell us what is impossible. It is impossible under ordinary arithmetic that 2+2=5. It is impossible in the real world for a rock not to fall when you drop it.
But our moral beliefs are always about what is possible, but bad. It's possible to steal from people, it's possible to kill people. We don't have any ethical beliefs governing the proper use of telepathy precisely because it's impossible to read people's minds.
There just isn't any sort of epistemic basis for knowing the truth of a statement of ethics that doesn't discuss what someone believes about ethics.
But people do have ethical beliefs, and MESR explicitly recognizes those beliefs; MESR is therefore not a nihilistic theory. I'll talk about how we can and do use MESR in important philosophical and practical ways in part 3.
 No statement in philosophy is utterly without controversy: There are those who would deny that mental states exist, i.e. that any sort of subjectivism is entirely fictional, even to the extent of abstract properties supervening on physical neurological properties. But that's an argument for another day.
 Technically, MESR is a "realistic" theory because it references subjective entities, which are real. Classical theories of moral realism, though, tend to refer to objective (non-minded) entities.
 See The Vacuity of "relativism".
 See Psychological Egoism for an argument showing why this formulation is not tautological.
 For the annoyingly particular, it's impossible for gravity not to accelerate the rock.