Hello Bob, I'm happy to explore morality with you on multiple fronts here, as its a very deep topic and requires a lot of consideration from all possible sides. This is a good breakdown of your theory and seems very well written and clear. However, I see some issues with a few of the statements. Lets start at the top.
First, I agree with your pre-requisite to Meta-ethics section! Its good grounds to start and needed for the discussion. If I were to say one thing, it is to go back and clearly define what you mean by objective and subjective as well. Onto the discussion!
P1: The way reality is does not entail how it ought to be.
P2: Moral facts are statements about how reality is such that it informs us how it ought to be.
C: Therefore, moral facts cannot exist. — Bob Ross
In very simple terms, this doesn't work because you forgot the possibility of different states of reality. If we took a frozen snapshot of existence, or how things are, without any other comparisons; you would be correct. But if we have seen multiple states of existence, we can compare different states and claim, "That state of reality is superior to this state of reality."
Lets flesh out your statement so that its conclusion can be true.
P1: The way reality is at any moment, in isolation of any other consideration of other potential states of reality, does not entail how it ought to be.
P2: Moral facts are statements about how reality is such that it informs us how it ought to be. This requires a consideration of states of reality in comparison to the current state of reality.
C: Therefore, if we consider a state of reality in isolation of all other potential states of reality throughout time, moral facts cannot exist.
And I would agree with this. But lets include other potential states of reality.
P1: The way reality is at any moment, in isolation of any other consideration of other potential states of reality, does not entail how it ought to be.
P2: But, if we include other potential states of reality, we can compare them to declare that one state is better over another.
P3: Moral facts are statements about how reality is such that it informs us how it ought to be.
C: We do not have the criteria yet for "what is better" so cannot determine at this time if it is objective or subjective.
So I do not see the original conclusion: "Therefore, moral facts cannot exist." once you introduce comparative potential states of reality. Still, lets continue onto your argument for subjective morality, as the above argument is simply a clarification of what must be considered when addressing morality, and does not make any claims to whether moral claims are subjective or objective.
1. Moral judgments are propositional [moral cognitivism]; and
2. Moral judgments express something subjective [moral non-objectivism]; and
3. There is at least one true moral judgment [moral non-nihilism]. — Bob Ross
Lets agree with points 1 and 2 and see if it necessarily leads to your conclusion.
First, this is really going to come down to your definition of what is objective and subjective.
"Something is subjective if it is dependent on a mind (biases, perception, emotions, opinions, imagination, or conscious experience).
Something is objective if it can be confirmed independent of a mind."
https://en.wikipedia.org/wiki/Subjectivity_and_objectivity_(philosophy)
I think these are fairly uncontroversial and straight forward definitions, so lets start here.
Lets now go back to your definition of truth which I agree with:
‘truth’ is the ‘correspondence/agreement of thought with reality’ — Bob Ross
Now, is truth subjective, or objective? If it is subjective, then it cannot be determined independently of a mind. If it is objective, then it can be confirmed independently of a mind.
If truth is merely the correspondence of thought with reality, then it needs no mind. Truth is simply a 'state'. "Thought is in correspondence with reality". If we were able to be aware of this, we might call it knowledge. But truth does not require knowledge. Truth is simply a state of being that is unconcerned if there is an observer there to realize it.
Thus truth is best described as "objective'. With this, we can now examine your conclusion.
3. There is at least one true moral judgment [moral non-nihilism].[/quote]
If there is a true moral judgement, then it must be an objective moral judgement. If moral judgements are subjective, and only subjective, your conclusion does not follow. For there to be a true moral judgement, a moral judgement must be objectively in line with reality. But if there is a moral judgement that is in line with reality, it is objectively true, not subjectively true. The subjects opinion to the matter is irrelevant.
But, can we salvage the intent of your theory? Lets try.
(Subjectivity and objectivity continued from the wiki citation)
"If a claim is true exclusively when considering the claim from the viewpoint of a sentient being, it is subjectively true. For example, one person may consider the weather to be pleasantly warm, and another person may consider the same weather to be too hot; both views are subjective. The word subjectivity comes from subject in a philosophical sense, meaning an individual who possesses unique conscious experiences, such as perspectives, feelings, beliefs, and desires, or who (consciously) acts upon or wields power over some other entity (an object).
If a claim is true even when considering it outside the viewpoint of a sentient being (how ?), then it is labelled objectively true. Scientific objectivity is practicing science while intentionally reducing partiality, biases, or external influences. Moral objectivity is the concept of moral or ethical codes being compared to one another through a set of universal facts or a universal perspective and not through differing conflicting perspectives. Journalistic objectivity is the reporting of facts and news with minimal personal bias or in an impartial or politically neutral manner."
Lets examine the idea of 'subjective truth'. Person A states, "Its hot" while person B states, "Its cool". From their perspectives, this is true. But how is it true? How is it 'in correspondence with reality" if we've claimed truth is objective?
Its because we've left out the implicit information within their statements.
Person A: From my subjective experience, I feel its hot.
Person B: From my subjective experience, I feel its cold.
These are both subjectively true, because it is objective. The feelings of a subject in reference to itself are objectively true. What one's subjective experience entails, is objectively true. We have a non-truth when this happens:
Person A: From my subjective experience, I feel its hot, therefore I will claim it is hot for everyone else.
Person B: From my subjective experience, I feel its cold, therefore I will claim it is cold for everyone else.
At this point, the conclusion is not objectively true. Its a subjective belief.
How do we tie this then back into a subjective morality? Lets examine your claim about subjective morality:
Within moral subjectivism, the moral judgment is a belief which is the upshot of one’s psychology and it is proposition which is indexical—e.g., ‘I believe one ought not torture babies for fun’ is a moral judgment, and the belief about the belief attempts to determine the truth of the claim: either I believe one ought not to torture babies for fun or I don’t. — Bob Ross
Bob Ross: From my subjective viewpoint, I believe moral judgements are based on psychology, therefore all moral judgements are based on psychology.
As we can see, this is a subjective claim, and not objective. Just because you personally believe moral judgements are based on psychology, this does not make it true objectively or subjectively. While you could create a subjective truth by simply claiming, "From my subjective viewpoint, I believe moral judgements are based on psychology.", it is your claim that this is a truth that all people must objectively conclude about morality that makes it objectively and subjectively false.
I also wanted to address a couple of your points/counterpoints, but not go too long on this initial reply.
For there to be true moral judgments, is just to say that we have good reasons to believe that some of the truth-apt (cognitive) moral judgments we have are true and thusly binding. — Bob Ross
Your own definition of truth counters this statement. Your definition of truth indicated no necessity that a person have knowledge or justification of something being true. A true moral judgement simply needs to be in correspondence with reality. The only thing you can state with your definition of truth is:
"For there to be true moral judgments, is just to say that our moral judgement corresponds to reality."
Another point:
P1: If there are no true moral judgments, then one would have to ‘lie down and starve to death’. — Bob Ross
This statement is a contradiction. If there are no moral judgements, then there is nothing one has to do. Therefore one would not have to 'lie down and starve to death'.
Finally:
P1: If there are true moral judgments and they are not an expression of something objective, then they must be an expression of something subjective. — Bob Ross
Except that if something is true, it is in correspondence with reality objectively. The subjective knowledge or lack of knowledge is irrelevant. Therefore if there are true moral judgements, then they are objective.