I.e. rational is a marker you can put on one kind of thinking/feeling versus other kinds, but that is something you do. In other words rational is a mental/cognitive word for which there is no external, outside and/or objective reference point. Rational is a quality, not a quantity and it has no mind/self/subjective independence.
Rational is a quality, yeah; so? That doesn't mean judgments of rationality aren't objectively true or false. Qualitative judgments can be objective. Actually, I think all quantitative judgments are
based on qualitative ones: for example, the left end of the object is lined up with the left end of the meter-stick, and the right end of the object is to the right of the "12 cm" mark. Therefore the object is longer than 12 cm.
So let me get this straight. You argue that morality rested on those virtues everyone rationally values in others (and which hence always constitute communal interest) and that hence meant that moral realism was correct.
Hm, dame that sounds frightening plausible I must admit ^^ I can think of animal rights as an counter-example. Some people (including me) believe that certain moral obligations apply to all living things with an emotional life - would that be hence wrong because "respecting the emotional world of animals" does not constitute such a virtue, nor can it be traced back to it? Hm, well we could trace it back to compassion. People want others to have compassion and compassion means in practice to be sensitive to the emotional needs of others. I suppose one could focus on emotional needs and leave the human part out. Yet many people - quit rationally as they don't depend on the goodwill of animals - would not want that. From that I conclude, that virtues can not establish an absolute unlimited moral truth as the exact understanding and weighting of virtues still matters.
Compassion is important, but so are the rational desires of members of the community. Because so many members care about how animals are treated, and we can make rules that provide some basic protections to animals without seriously impinging on the freedom of those who don't care about animals, those laws are justifiable. Part of the justification is that the laws express the compassionate values of the society, and society needs those kind of values to flourish; but another part of the justification is that these concerns by animal-lovers are rationally stable, and society ought to promote the rational concerns of many individuals, provided it can do so without consistently disadvantaging other groups. "You win some policy battles, you lose some" is fair; "Let's all gang up on the Rastafarians and take their stuff" is not.
But it would still be a great leap towards moral realism. But what about utilitarianism? Utilitarianism chooses to view virtues not as an end in itself, but merely as an end to raise the quality.
Utilitarians can certainly endorse specific virtues, and also specific rules. If an act can be evaluated by its consequences, why not a virtue? Why not a moral rule?
Classical utilitarianism, though, cannot be vindicated on a meta-ethical view like mine, I think. The reason why, is that justification is distributed, not collective. That is, each member of society must be able to rationally accept the results of moral discussion. Of course, each individual recognizes that they cannot get their own way on everything, since others wouldn't rationally accept that. But they have to get some respect - and I don't think "having your utility counted in the calculus" counts as adequate respect. It's too risky, at least for some individuals.
Also, your concept requires the assumption, that good and bad depends on shared rational interest. How can we establish this notion as the absolute truth?
Not all good and bad, just moral good and bad. And maybe not
all moral good and bad, either - just certain (very important) domains like justice. I don't think we
need to establish that conception of "justice" as the
absolute truth. Instead, like any other hypothesis, we try it on, and see if it seems to provide an elegant explanation of what we observe.