You’re right, objective morality means that it exists independently of humanity, and I should have included that in my description. I was emphasizing the “universal applicability” feature of morality since your argument for subjective morality relied on the fact that there are moral disagreements among different people and cultures. However, your argument seems to have shifted emphasis, now noting (accurately) that universal agreement on even just one moral act isn’t enough. It appears that you agree that my example of “killing people for pleasure is wrong” is universally agreed upon (or at least as close to universal as can ever be achieved).
It’s true that objective morality would mean, in theory, that every human could agree that X is morally right and yet be incorrect on the basis of the objective standard. (In practice, I don’t believe this happens because God writes His law on our hearts – Romans 2:14-16 – but I agree that it is in theory possible: let God be true and every man a liar! Romans 3:4).
Interestingly, the quote that you linked to does not use this as a reason that objective morality doesn’t exist, but a reason that we wouldn’t want objective morality to exist. That difference is vital; more on that in a bit.
Significantly, the desire to affirm/choose a subjective morality simply so that we have moral autonomy over ourselves itself suggests a “second level” objective moral principle: it asserts that autonomy in moral choices is good. That is a moral assertion! If that assertion is just the opinion of the person making the claim, then there is nothing to compel anyone else to agree with it. If, however, it is asserted with the intent to convince the reader to agree (as appears to be the implication, for why else would the author spend the effort and time writing it in the first place?), then it appeals to a standard which is independent of the author and the reader. If that standard is subjective (not independent of humanity), then still no one could be objectively faulted for disagreement; one could be subjectively faulted, i.e. “I don’t like that you deny that moral autonomy is good,” but that’s different than saying “you are wrong to deny that moral autonomy is good.” Even if I were the only human who ever lived who disagreed with that assertion, if there is no objective standard (independent of humanity) to which I am accountable, then others can say that they don’t like my choices, but they cannot call my choices wrong. If one would reply that, “you should comply with assertion X for reason Y,” it assumes that reason Y is something with the moral authority to compel me to (this is more than saying, “if you don’t comply, you will be punished,” for that is a pragmatic and not an inherently moral reason; to say that I should do something in the moral sense of “should” is to imply a standard of “moral should” to which all humans are accountable – an objective standard). With no objective standard by which to judge, no one has a real reason to prefer one moral judgment to another, for as soon as they try to introduce a reason to agree with them, they assume that the reason has authority to apply to you, no matter who you are, what you want, or how you feel. That implies the standard to which they appeal is external to humanity (it supersedes human thoughts, desires, will, and plans), and therefore is objective.
The blog you linked to has the same problems. For example, in the paragraph beginning “Subjective does not mean that anyone’s opinion is ‘just as good’,” it mentions the notions of “good” and “strong.” This appeals to a sense of good and strong which, if not objective, are literally without meaning. If my idea of “good” is different than yours, how can we choose between us which one is “right?” If the answer has to do with common agreement, then we have only determined which of our ideas is more popular, but that has nothing to do with being right. It relies on precisely the thing it argues against. I see other issues with it, for example questions like, “even if morality were objective, how would we know what the right morality is?” [my paraphrase], or pragmatic decisions which ostensibly would be eased by accepting subjective morality, both of which are red herrings. And the claim that a God-based objective morality would either be below Him or above Him, which creates a false dichotomy – morality which is part of His nature is neither, and since He is separate from humanity, a morality rooted in His nature is objective because it is external to humanity. And there are others, but my main point here is not to respond to that blog.
In summary, I find that arguments for subjective morality clandestinely sneak in objective morality in order to argue against it.
It seems our disagreement may come down to what is meant by labeling someone else’s actions to be morally wrong. If I call something wrong and merely mean that I (and possibly a large number of others, even up to all of humanity) don’t like it – well, this to me is a misuse of the word “wrong.” In this context, I use the word to mean that there is something which compels that person to not behave that way for the sake of the act itself; the act is inherently wrong, regardless of the practical consequences and (collective) feelings. It means there is a core, inherent attribute of that act which ought not to be done. Such a scenario cannot arise without an objective standard. Without an objective stick to measure against, nothing can be inherently right or wrong. Thus, if anything is morally “wrong” in this sense, it must be objectively wrong.
When I use my “killing for pleasure” example, I use it with that intent: not to justify objective morality, but to show people that they already believe in it. (I’m glad you brought this up because in hindsight my intent with that example wasn’t clear.) This example shows that the vast majority of people already believe there is a standard “out there” which is authoritative and independent of human opinion. They see that they already believe that killing for pleasure is not just unpopular, but it’s flat out wrong (meaning there is an objective standard, external to all humanity), even if a great deception were to sweep the world and change everyone’s mind. That example is about revealing what people already think, and it by itself is not meant as rational support for an objective morality. Once a person recognizes they agree with those statements, then the premise of TAG is met.
A quick word about the “animals and aliens:” the fact that human morality doesn’t apply to animals or aliens (that we know of) reflects the unique, higher moral complexity of humans. Of all the creatures we know and as far as we have observed, only humans have that level of complexity, which is why human morality is different. Humans are made in the image of God, unlike all other creatures (that we know of). Thus, human morality applying only to humans doesn’t weaken the claim that the morality is objective. After all, even if other species or aliens had completely different morality than humans, the present discussion is only about whether human morality is independent of humans – that was our definition of “objective.” Morality (or lack thereof) of other creatures is irrelevant.
You and I have been down this road before, and frankly I don’t have much confidence that either one of us is going to convince the other. What disturbs me is that the reason you cited to support subjective morality: so that human desires can reign supreme. This is a deadly spiritual desire, and it is precisely why the Bible says that some will deny Jesus (because they “love darkness rather than light, for their deeds were evil,” says John 3:19). They try to make themselves into the “supreme being” in their lives. It doesn’t end well for them (Romans 1:18-19). You are made in God’s image and He loves you, and therefore so do I. Because of that, @T_aquaticus, and for your own sake, I don’t want you to go down that path. I present TAG and the supporting statements for that purpose.