If you've read the posts so far, you've seen that, for the theist, everything centers on morality. People have to objectively deserve a punishment or reward. This inevitably leads us to ask what is required to establish something as objective.
There are several definitions of the term objective. Objective can mean inter-subjective, i.e., that people can come to some agreement about a convention. However, what we are looking for is a meaning of objective that roughly equates to "true independent of our present beliefs about it." This appears as a desire to know "The Truth" about the world.
We are handicapped because everything that comes through our minds is filtered by our experiences which are subjective. We have no way to know whether or not we are brains in a vat that dream the world as we see it. So "The Truth" as children like to think of it is a non-starter. There is no way to know a truth beyond experience because experience is our window on truth.
However, we are intuitively aware of a distinction between objective and subjective. And we can devise rigorous tests for objectivity and subjectivity.
My claim is that objectivity is a word we give to properties of things that appear to be distinct from ourselves. A good example is taste in food. I like chocolate. We believe chocolate exists objectively, and that it contains fats and sugars. However, my liking chocolate is about my interaction with chocolate, not about the chocolate itself. We would not say that chocolate objectively contains doctor(logic)-likability. We could say that, but then we would obliterate all subjectivity by hiding it in objective likability properties, and that starts to look silly from certain perspective.
So what I am saying is that a subjective fact about a thing is a fact about my interaction with that thing, not about the thing itself. In other words, if you did not know anything about me, you would not be able to fix that fact by looking at the thing itself. Not knowing anything about doctor(logic), you could not fix the doctor(logic)-likability of Doris Day.
The challenge is that it is difficult for me, doctor(logic), to isolate whether a property of a thing is in the thing itself versus in my interaction with the thing. I hear the sounds of a Mozart symphony, and it sounds good. I am objectively sensitive to the sound of the music, but the aesthetic goodness of the sound is subjective.
I proposed two tests for objective properties, one of which is a limited version of the other. In the case of the Mozart symphony, it's possible to sense the sound independent of knowing that it is a Mozart symphony. However, it is not possible to sense the aesthetic goodness without hearing the the whole piece. I cannot sense the goodness alone, but I can sense the sound alone. If I could sense the goodness alone, I would have good reason to believe that the goodness was part of Mozart's symphony, and not simply my reaction to it.
The key to this test is blinding oneself to all but one property of a thing. If we can do this, then we have good reason to believe that this property is part of the thing and not a part of our interaction with the thing.
This isn't proof that goodness is subjective, but it is the only kind of distinction we can make. Were we to assume that the aesthetic goodness of a symphony is out there, but that some poor bastards are blind to it, then we could say the same of any property we can perceive. That would mean that if you like red wine more than white, you could argue that red wine was objectively better, and people who did not like it more were crippled in some way. And presumably, people who prefer white wine ought to seek surgery or counseling for their defect.
Returning to my test, we can try this on all sorts of categories that are normally regarded as subjective and objective and see how the test works out:
Subjective / Objective
Musical taste / Musical sound
Gastronomic taste / Food chemistry
Art taste / Geometry, color, texture
Cultural taste / History, political facts, traditions
Moral taste, justice / Actions, decisions, consequences, law
In these cases, we can see that it is not possible to isolate good art, good food, good culture, good morality, or good music from a thing. Yet we can isolate the objective properties of things in a fairly straightforward way.
For example, I can devise a way to identify the sugar in a food without tasting the food in its totality. I can even make a machine that will detect its sweetness. And yet I will never know whether it is good food until I taste it as a whole.
I described my two tests in detail here.
Now, theists could make (but haven't made) the objection that there are objective emergent properties of wholes. For example, they might claim that the goodness of a Mozart symphony emerges from the whole, and that even a complete analysis of beats and times and tones and structure would not reveal the holistic property of the piece. As a holistic property, this property cannot be isolated from the other properties that are relevant to that whole.
While this objection seems reasonable to me, it doesn't really help. We knew from the start that it was possible for some properties to be objective even if we could not make that distinction. The objection fails because, were we to accept that any perceived attribute of the whole is some objective holistic property, then again we would utterly destroy the subjective/objective distinction.
Alas, there are no serious objections that I have seen.
Theists will say that if there's no objective morality, then eating babies is okay, but since doctor(logic) does not subjectively believe eating babies is okay, eating babies must be objectively wrong. Their arguments are that bad. That's why they insist that moral relativists like myself should never use the terms ought or should.
Of course, they are begging the question to the max. An inherent feature of moral oughts is that individuals will claim one ought to do a thing, and act to enforce or encourage such oughts. This is the phenomenon we are studying. The question we are considering is whether moral oughts are subjective or objective, whether we possess oughts due to accidents of our nature or because we perceive a reality of oughts external to ourselves. It is irrational to then turn around and claim that the phenomenon does not exist unless moral oughts are objective and external.
Once again, it all comes down to morality. If there is no moral reality, how can we be trusted to do cultural good instead of evil?