As a moral subjectivist, I am committed to three propositions.
1. Moral statements are truth apt.
2. Some moral statements are true.
3. The truth aptness of moral statements are dependent upon the subject in which they are indexed next to. — Cartesian trigger-puppets
No, that's not correct. 1 is true. But 2 is false - you are not committed to realism. I mean, admittedly it'd be quite odd to be a subjectivist and think that morality is unreal (though one could, for it is metaphysically possible that there are no subjects, or that all the subjects that there are are not in the subjective states that constitute the truth-conditions of moral propositions). The point, though, is that 'realism' is not an essential element of subjectivism (or non-naturalism, or naturalism, or super-naturalism). You keep making this mistake. It's like insisting that incompatibilists about free will believe we have free will. No, incompatibilism is a view about what free will requires, it is not a view about whether we have it or not. Likewise for compatibilism. And likewise for subjectivism, naturalism, non-naturalism, supernaturalism, and non-cognitivism. They're not - not - views about what exists.
I gave you an example that you seem to have ignored. The view that milkshake is made from milk and flavouring is not equivalent to hte view that there exists milkshake. I have just told you my theory about what milkshake is made from. I have not told you that I have some milkshake.
3 is misleading. I think what you mean is that the truth conditions of a moral proposition would be some of the subjective states of the subject. That is essential to subjectivism - it is what makes it subjectivism. A moral subjectivist is something who thinks that moral norms and values are made of the prescriptions and values of a subject (a 'subject of experiences' that is - a mind). And individual subjectivism, which is the view that no serious philosopher defends because it is has even less to be said for it than naturalism or non-naturalism or expressivism, is the view that the subject in question is ourselves.
So, whether "X is morally right" is true or not is constitutively determined by some of my own subjective states if, that is, individual subjectivism is true. Which is absurd of course - as absurd as individual subjectivism about teapots.
That's not correct. Naturalism and non-naturalism are are not theories about what actually exists.
— Bartricks
That was not the point I was making at all. — Cartesian trigger-puppets
But you said something straightforwardly false. It is clear from my OP that I am addressing naturalism, non-naturalism and expressivism. They are 'not' forms of moral realism. The question of whether morality is real is a distinct one, but you are confusing what's already a confusing matter by introducing it.
So again: naturalism and non-naturalism are views about the ingredients of morality, they are not existential theories about what exists. And expressivism is the view that morality doesn't have ingredients because it is not a feature of reality that we observe and respond to, but an activity we engage in. But none of those theories carries with it any commitment to this or that existing.
(Argument 3 supporting P2: Argument 2)
1. If moral statements are cognitive expressions of propositional attitudes, then they express propositions about the attitude of an individual subject.
2. Moral statements are cognitive expressions of propositional attitudes.
3. Therefore, moral statements express propositions about the attitude of an individual subject. — Cartesian trigger-puppets
What work is the word 'cognitive' doing? I only ask, because a) I do not know what it means and b) most metaethical discussion seems to be made needlessly complex by this kind of technical vocabulary.
Anyway, 1 seems obviously false. Yes, moral statements are about propositional attitudes, but why on earth does that mean that they are about the attitudes of the utterer?
If I say "Cartesian trigger puppets wants me to shut the door" that is about a proposition attitude. But it is not about my attitudes, but yours.
So that first argument is clearly unsound and flagrantly question begging. Premise 1 just asserts the truth of individual subjectivism - a theory that appears to be false, not true - and then you just deduce from it the truth of individual subjectivism.
1. If moral beliefs are cognitive evaluations and propositions are objects of belief, then moral statements are cognitive expressions of propositional attitudes.
2. Moral beliefs are cognitive evaluations and propositions are the objects of belief.
3. Therefore, moral statements are cognitive expressions of propositional attitudes. — Cartesian trigger-puppets
That argument is very confused. First, the conclusion does not seem to describe individual subjectivism, but expressivism (although I don't know what 'cognitive' means, admittedly). But to 'express' an attitude is a different linguistic activity to 'describing it'. "Hooray" expresses an attitude, and "I am ecstatic" describes one.
But in addition to being an argument for a view distinct from the one you were seeking to defend with it, it is also unsound, for premise 1 is once more simply false and question begging.