If you are arguing that morality is subjective then by definition you are arguing for moral relativity. I can easily prove absolute morality by asking you a very simple question. Do you - not society, past, or future, believe it is wrong for humans to own other humans beings?
I am not asking you what society says about this. I am asking what you believe about this. Do you believe this would ever be moral?
Well I disagree that I believe in "moral relativism" as an absolute. I do not. I do believe there are certain things (though very few) that the overwhelming majority of humans agree upon morally regardless of culture or time. Often times, what this breaks down around is
definitions.
You ask if I believe it is moral to own another human being. I do not. I wouldn't have believed that in 1861 and I don't believe most people would have. The difference is in definition of what a "human being" was... a slave was a piece of property, not a human being. Society justified the morality of owning slaves by distinguishing them as property and
not human beings. The same thing happens today with regard to unborn fetuses.
We can look at the radical Islamic teachings... these people justify what they do as "moral" because they think it's justified to rid the planet of infidels and Jews. I hope you don't agree with them, I certainly don't agree with them, but they religiously believe they are being moral. They want to impose brutal Sharia Law on society, they think and religiously believe that is moral. We don't agree with them but that's the morality they've justified. Why hasn't your ethereal and universally eternal morality permeated their thoughts? Why don't they realize naturally that what they are doing is immoral?
Then you have just proven my point. You have discovered the moral law for this specific subject. That it is wrong to treat human beings as property to be disposed of at the will of its owner. It was always wrong to treat human beings as property to be disposed of at the will of its owner. And that it will always be wrong to treat human beings as property to be disposed of at the will of its owner. There is nothing relative about your belief.
So just because society's beliefs were relative on this subject, that did not negate the moral law on this subject. And since this was not always accepted as the moral law on this subject, it was eventually discovered to be the moral law on this subject, thus proving that the moral law is discovered... eventually.
Yes, I agree with you that we as a society have relegated the unborn to property to be disposed of at the will of its owner. I believe this is against the moral law of nature.
Well I don't see where I proved anything other than your OP premise as being incorrect and invalid. While OUR society recognizes slavery is immoral and wrong, it STILL exists in other societies. So there isn't a universal understanding even on something as apparent as this. Justifications are still made for immoral behavior and they always will be... that's the inclination of man.
Again, let's take homosexuality as an example. In ancient Greece, homosexuality prevailed as a moral right of passage. It was considered part of the culture and absolutely moral. Flash-forward to Puritanical western society where homosexuality was viewed as morally reprehensible and shunned for years. Only recently have we relaxed our laws and made homosexuality legal and now, in fact, a recognized protected class. What IS the TRUE "natural morality" on that?
Same with 14-year-old girls getting married... How do we KNOW we're at the "naturally moral" position? If there is supposed to be some natural moral truth to this, we should be
aware of it, right? Now you can say... Well "Age 16" is the
natural moral right and any time prior to that is morally wrong... that's a subjective opinion based on nothing other than your abstract moral values. It's not rooted in nature because nature shows NO indication of bestowing ability of consent on any given day and time. This ability depends largely on the maturity of the individual.
What you are attempting to do here is establish some universal morality that is true and which you want everyone to accept. But you don't get to decide that for everyone. We may differ greatly on what we consider "moral" or "immoral" depending on our perspective. I don't consider it "moral" to lock people up and steal their property because they planted a weed in their backyard. Others disagree with me and think it's upholding a moral standard to do so. There is no "natural moral truth" there, it's subjective and depends on individual perspective.