The middle-ground certainly
is wishy-washy, which is relativism's whole point, really.
>Moderate meta-ethical relativism (as described in your link) postulates that there are some universal rules for morality.
Not so? "Meta-ethical relativism: that there is no single true or most justified morality". I am skeptical "about the meaningfulness of talking about truth defined independently of the theories and justificatory practices of particular communities of discourse". I'll elaborate and tie this in to your next point...
>If you actually hold the view that there are common universal morals that can be pulled from the commonalities of all disparate human morals, then you're a secret moral universalist.
I like the evolutionary idea ( https://en.wikipedia.org/wiki/Moral_relativism#Scientific ). I.e. the reason there are certain common morals (i.e. don't kill innocents, raise and protect children, etc.) is that these offer a strong advantage over other groups that do not hold those morals. So these morals end up in nearly every single society, and could be easily mistaken for "universal" moral truths. From my original article: "a common feature of adequate moralities is the specification of duties to care and educate the young, a necessity given the prolonged state of dependency of human offspring and the fact that they require a good deal of teaching to play their roles in social cooperation. It may also be a common feature of adequate moralities to require of the young reciprocal duties to honour and respect those who bring them up, and this may arise partly from role that such reciprocity plays in ensuring that those who are charged with caring for the young have sufficient motivation to do so". Using the language of that quote, and to twist your example: rules A, B, and C are common elements of an adequate moral system, and then you can optionally add arbitrary rules D-Z depending on your culture and preferences.
Consider infanticide in the animal kingdom (https://en.wikipedia.org/wiki/Infanticide_(zoology) ), this would be "immoral" for humans, but it is standard practice for some species given the right circumstances. So for humans there may be near-universal morals, but they only apply to us, and only because they "evolved" that way. A human tribe that had a similar practice of infanticide might be more likely to die off (and take its "moral truths" with it) because humans don't reach maturity fast enough to support a generational purge of all infants.
You might say this is where I'm squinting, but I would say we just have different tests for what constitutes a "universal" moral truth. Perhaps just as you pointed out the case of there being a "false equivalency between the two different loves being discussed" I would suggest we're ignoring the false equivalency between the two different universals being discussed.
The "universal" you think I hold is an evolutionary (and therefore arbitrary, uncaring, and accidental) one that is specific to our species. That, by definition, is relative, not absolute. There's nothing timeless or intrinsic to such a "universal morality". You might say this means I'm just squinting hard enough, but I disagree. The big supporters of universal morality are theists who use their God(s) as external observers to pass moral judgement. Because without some external observer, what makes any moral truth "universal"? I.e. where would the "universal morals" come from-- who or what would set the standard? If you agree that humans collectively agree on the standard, then for my definition of "universal" they would not be universal.
You're interested in finding meaning, though. Meaning is relative to an observer, it can't be "found" in the sense that it's waiting out there somewhere for you. Meaning must ultimately come from within. Take any sandbox game for instance, it's like you're saying "Minecraft is meaningless because there's no point". Notch created the world, but gave no direction. All the gameplay is emergent. Real life is like that.
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As an aside, thanks for engaging. This has been a really interesting discussion and has lead me to plumb the depths of moral philosophy way deeper than I had ever before gone.