Moral subjectivism is false.

Circularity and IncoherenceCon's response here utterly misses the point and that may be my fault for not making it clear). In other words moral subjectivism descends into a viscous circularity. In order for us to know what it is for some "x" to be believed to be "good", we have to first know what "good" is. But if "x is good" just is "the speaker believes that x is good" (because, remember, it is plausible to suppose that approval just is a moral belief) and "the speaker believes that x is good" just is "x is good" we still don't know what it is for "x" to believed to be "good". This is a classic example of a circular definition:A circular definition is one that uses the term(s) being defined as a part of the definition or assumes a prior understanding of the term being defined. Either the audience must already know the meaning of the key term(s), or the definition is deficient in including the term(s) to be defined in the definition itself. Such definitions lead to a need for additional information that motivated someone to look at the definition in the first place and, thus, violate the principle of providing new or useful information. If someone wants to know what a cellular phone is, telling them that it is a "phone that is cellular" will not be especially illuminating. Much more helpful would be to explain the concept of a cell in the context of telecommunications, or at least to make some reference to portability. The 2007 Merriam-Webster dictionary defines a "hill" and a "mountain" this way: Hill - "1: a usually rounded natural elevation of land lower than a mountain" Mountain - "1a: a landmass that projects conspicuously above its surroundings and is higher than a hill" .... In short: the two words define each other. [1]On subjectivism:With all that said, we can easily see howNon-subjectivist: What does "x is good" mean?Subjectivist: The speaker approves of x.Non-subjectivst: Okay....well, what is the speaker of approving of x mean?Subjectivist: X is good.Non-subjectivist: *blank stare*The incoherency comes in when we have "good" be in the explanation of "x is good" coupled with the theory that the truth just consists of a particular speaker believing it. In that case we go back to the original formula I gave in the first round. If [x is good] = [the speaker believes x is good] then, naturally, [the speaker believes x is good] = [the speaker believes (the speaker believes x is good)]. Then [the speaker believes (the speaker believes x is good)] = [the speaker believes (the speaker believes (the speaker believes x is good))]. And on and on and on, ad infiintumTo refute one of Con's examples to make my point clear, saying something is true does not suffer from my line of reasoning at al.Let's say:Truth = correspondence with a fact (or reality).Reality = the actual state of affairs (as opposed to imagined or appeared).Note that "truth" doesn't appear in the explanation of what truth nor does truth obtaining consist solely in a person believing it (so it's not open to the incoherency objection) and it is is not a circular definition (so it is not open to the circularity objection).Thus we can see that Con's parity of reasoning objection fails. And subjectivism still seems to be incoherent and viciously circular.No Moral DisagreementNot quite. I'm saying that we naturally assume that we have actual, real moral disagreements about facts of the matter, and this is prima facie evidence against moral subjectivism (because there can't be any moral disagreement on subjectivism). It may be the the case that our assumption is wrong, but Con has given us no reason to suppose so. The best explanation of why we assume we are disagreeing about facts of the matter beyond our psychological states is that...we are disagreeing about facts of the matter beyond our psychological states.Here Pro states that I assume that we cannot debate things unless we have an objective answer. This is false. What I'm saying is that on moral subjectivism you aren't actually disagreeing. Person A can agree with person B that person B approves of child rape, and that for them, child rape is good. Because, after all, goodness of child rape just consists of person B's approval of it (and that approval is just a description of their belief). Person B can also agree with person A that person A disapproves of child rape, and that for them, child rape is bad. Again, that's just describing person A's psychological state. You can't disagree with someone's report of a psychological state unless you think they aren't truthfully reporting their (dis)approval. There's nothing to disagree on here on subjectivism; there is no fact of the matter to disagree with, they agree on all the same facts of matter. On non-subjectivism person A could agree that that person B approves of child rape, but they cannot agree that child rape is good because that is mutually inconsistent with person A's belief that it is not good. In this case, there a fact of the matter they are disagreeing about. Contra Con, there are no real moral disputes/disagreements given subjectivism and this counts as a substantial mark against subjectivism unless Con can give a reason why it's reasonable to not believe there is actual moral disagreement. Hence Con's rebuttal here just misses the point of the objection.Moral InfallibilityCon, in his attempt at rebuttal here, actually just makes my case for me. Since subjectivism reduces all moral beliefs down to reports of our psychological states (opinions and so forth), there are actually nothing to consider and deliberate on. That would imply that the reasons that Con's father gives him to change his mind about the goodness of punching old people in the mouth figure into his (dis)approval of the act (which takes me back to the earlier 4th point of arbitrariness I made in the first round). After all, what could Con be considering? That his previous approval of punching old people in the mouth didn't actually have any good reason to back it up? But, on subjectivism,, those reasons don't figure into determining what is good or not; only Con's approval does. It's fairly easy to introspect and tell when you approve or disapprove of something. The reasons we usually can't tell or have doubts about whether we disapprove or approve of something is because we are unsure if we have good reasons for that approval/disapproval. Subjectivism does not make that distinction. This is just how it is when considering and deliberating on other matters of fact - like, say, the truth of the many world interpretation of quantum mechanics. Why should moral deliberation and considerations not be considered of the same type when they follow the same general form? What Con is doing is proposing a radical revision of moral discourse without any reason being given for this. Most of us naturally assume that rational considerations have a role to play when making moral judgements; subjectivism denies this. It denies that we can ever make a moral mistake and that counts against the theory. ArbitrarinessCon's case here hardly makes any sense. If the reason that you approve of x is what explains why x is good it can't be the case that approval itself is what makes x is good. The reason is independent of your psychological state. That makes it explanatorily prior to the approval of x. On subjectivism the approval itself is what makes x good. That is the necessary and sufficient condition. Con hasn't detailed what exactly the necessary and sufficient conditions for x is good to be, so saying the reason might be a necessary condition doesn't exactly say anything informative. And that is all it takes for x to be good; just approval of x. If you approve of x because you find it admirable, that admirability itself is explanatorily prior to your approval of x. Your approval of x doesn't make x admirable otherwise you had no reason to approve it beforehand. Which brings us back to the arbitrariness horn.Sources[1] http://en.wikipedia.org...