I sat down to write a blog post about this, and realized that I had already done it. Here’s the original: Personal Moral Relativism Collapses into Emotivism, via David S. Oderberg. But I can give a more succinct account here, for easy reference.
Here’s the basic point: Anyone who claims that moral judgments of the form “X is wrong” reduces to personal opinion, personal belief, personal view, etc. seems to be saying something incoherent. That is, the attempt to reduce moral judgments to the status of personal belief or opinions fails because it ends up being incoherent.
Why is this the case?
(1) Anyone who makes a claim like “A proposition of the form ‘X is wrong’ (e.g. ‘rape is wrong’) stated by P means only that ‘P believes that X is wrong’ or ‘In P’s opinion, X is wrong’,” is claiming that ‘P believes that X is wrong’ or ‘In P’s opinion, X is wrong’ gives the analysis or meaning of the expression “X is wrong.”
This analysis necessarily fails because “X is wrong” is supposed to be explained as “P believes that X is wrong” which contains the the proposition “X is wrong” embedded within it—and so this embedded portion of “P believes that X is wrong” still needs to be explained. If it is true that “X is wrong” means “P believes that X is wrong” then the “X is wrong” embedded inside “P believes that X is wrong” means “P believes that X is wrong,” which yields the analysis “P believes that P believes that X is wrong.” And “P believes that P believes that X is wrong” itself still contains the embedded “X is wrong” and so becomes “P believes that P believes that P believes that X is wrong” … which still contains the embedded “X is wrong,” which is therefore never explained at any level. All that is done is to set off an infinite regress which explains nothing at any point.
So attempting to analyze or give the meaning of “X is wrong” as someone’s belief or opinion or view that “X is wrong” is failed pseudo-analysis of moral propositions, being both infinite and failing at every point to give the meaning of “X is wrong.”
(2) Alternately one could attempt to analyze “X is wrong” stated by P as “P disapproves of X.” But now one needs to give the analysis or meaning of “P disapproves of X”—it should be clear that “P disapproves of X” cannot mean “P thinks that X is wrong” because this analysis would be both circular and generate same infinite regress problem above.
(3) One could hold that “X is wrong” stated by P means “P disapproves of X” where “P disapproves of X” is treated as a brute psychological fact without any rational content—it need not be analyzed because it has no rational content. But if the relativist makes this move, he is embracing emotivism, which entirely removes moral judgments from the sphere of reason altogether, which is not what the relativist meant originally when he said that moral judgments were personal judgments. He did not, presumably, mean at first to deny that they are judgments. He only wanted to claim that they were “personal” judgments. But clearly one cannot coherently hold that “all moral judgments are really only personal judgments and are also not judgments at all.”
The UPSHOT: The “personal relativist” needs to give a coherent analysis of moral judgments of the from “X is wrong” that (a) does not set off an infinite non-explanatory regress, (b) is not circular, and (c) does not collapse his position into a different position entirely, viz. emotivism.
Here is philosopher Davis S. Oderberg saying essentially the same thing:
First there is the semantic problem: A proposition of the form ‘Doing X is wrong’ uttered by P (for some action or type of behavior X and some person P) is, according to the personal relativist, supposed to mean no more nor less than ‘P disapproves of doing X’: the latter statement is claimed to give the meaning or analysis of the former. But ‘P disapproves of doing X’ cannot, on this analysis, be equivalent to ‘P believes that doing X is wrong’, since ‘Doing X is wrong’ is precisely what the relativist seeks to give the meaning of; in which case the analysis would be circular.
On the other hand, the relativist might again analyze the embedded sentence ‘Doing X is wrong’ in ‘P believes that doing X is wrong’ as ‘P believes that doing X is wrong’, and so on, for every embedded occurrence of ‘Doing X is wrong’, thus ending up with an infinite regress: ‘P believes that P believes that P believes . . . that doing X is wrong.’ This, of course, would he no analysis at all, being both infinite and leaving a proposition of the form ‘Doing X is wrong’ unanalyzed at every stage.
Such an obvious difficulty might make one wonder that any relativist should support such a way of trying to analyze ‘Doing X is wrong’; but if he is committed to the idea that morality is a matter of opinion or personal belief, it seems that he tacitly invokes just such a pseudo-analysis. The only other route the relativist can take is to assert that ‘P disapproves of doing X’ needs no further gloss: it is a brute statement of disapproval that does not itself invoke the concept of wrongness (or rightness, goodness and the like). But then personal relativism collapses into emotivism, the theory that moral statements are just expressions of feeling or emotion and only appear to have the form of judgements that can he true or false. Emotivism is a different theory from relativism, however, and more will he said about it in the next section. Unless the personal relativist can give an analysis of disapproval that is neither circular, nor infinitely regressive, nor collapses his theory into emotivism, he is in severe difficulty; and it is hard to see just what such an analysis would look like.