@BrettKunkleSTR You said that OMVs are self-evidently true. How can we know this? Why is there a connection drawn between our moral intuition and moral ontology? What is the limit in our methods of gathering data about this issue? We are limited by our own subjective moral experiences, and by others' accounts of their own subjective moral experiences. All I mean is when we have a moral intuition, or feel compelled to act morally, or have any sort of moral experience, all we can really know is that WE PERSONALLY feel like this or that is the right thing to do. The question of that intuition's veracity and objectivity remains unanswered.
The fact that most people agree on many moral issues doesn't help either. We (mostly) all feel that murder is wrong, but that doesn't actually tell us that the moral value, "murder is wrong", is truly objective. All it tells us is that we (mostly) all feel that murder is wrong. We can't know whether or not those intuitions are based on anything at all, or even if our moral intuition is actually "right" in the first place. All we can know is what we think about it and what others say they think about it.
This is all to hopefully more clearly illuminate my point. Since we are limited by only being able to actually perceive our own moral attitudes (what we really think, when no one is around), how would we be able to tell the difference between a truly objective moral value and a genetic adaptation that encourages moral behavior? They would both "feel" the same. You would "just know" that torturing babies for fun is wrong in the same way that you would if that was an objective moral truth (The instinctual genetic origin of such a moral intuition or conscience could be easily demonstrated with examples from our the wider animal kingdom). I don't think we can tell the difference by our intuition. There is no reliable way of determining if there are moral values and duties that are actually objective.
So when someone claims that it's obvious or self-evident that these moral values are objective, I think that's a simplistic view. When asked what the evidence is for thinking that there is an objective moral law, I think a more honest answer would be that it "feels" like they are objective. Because that's all you can really know. And that's not convincing to me.
So what can you say to the person who thinks that the existence of OMVs is not self-evident?
Next you said that if OMVs aren't real, then everything is subjective and that is rationally untenable. I don't know why it would be untenable. So I would disagree with you on that.
I do have some issues with the idea of objective moral values, but I think I would rather focus on the little stuff that can get forgotten in the moment but then causes confusion later because it was never fleshed out.
So if you would like to continue our discussion, we could do it on twitter, your website or mine (doubtingeric.blogspot.com, in the comments), or wherever you like.
In summary, please respond to the following objections I had to what you recently tweeted:
1) If morality was a genetic and social adaptation, deep in our programming, how could we tell the difference between two systems that feel the same from our view?
2) What reliable way can we know that objective moral values actually exist?
Intuition is unreliable, and why would the fact that I intuit something to be true be considered evidence that it really is true?
3) Why would morality being subjective be rationally untenable?
Again, sorry about the length. Twitter is not made for these discussions :)