What would be the harm?

[The Grand Nudger]

If I'm attempting to drown myself, then what value does oxygen have to me?  

The same value that it had before you attempted to drown yourself.  That you're doing so would probably indicate that you;re acting irrationally..but there may be some instance in which yuou might want to drown yourself for rational reasons.  Neither of these possibilities diminishes the objective value of oxygen as described. They're comments on your agency, and your subjective or relative -valuing-.

Hell, it's no stretch to say that it might even be..more properly, a comment on your state of general well-being.

I might see oxygen as my enemy, and wrap a rope around my neck, or fill a car with carbon monoxide, in order to prevent oxygen from doing the harm of forcing me to continue living a life to which I've attached a strong negative evaluation.

We can see things many ways, not all of the rational or true.  

In all your examples of so-called objective evaluation, you seem to me simply to be choosing subjective evaluation which are based on stronger and stronger feelings, and which are more and more common among individuals.  As much as we hate rape, most of us would dislike a total lack of oxygen that much less.

My examples of objectivity are those examples that rise to meet the criteria of objectivity as discussed by moral theorists.  That's all they have to do.  

And we're still at circular reasoning-- a "correct" evaluation of the value of oxygen depends on a "properly" functioning organism, which is at least partly defined as. . . an organism which can "correctly" evaluate the value of oxygen. . . n'est ce pas?

Except that it doesn't..since oxygen has value even to creatures that do not possess any such organ or mind, and even when those that do fail to apprehend it, and even when those that do lose their shit and try to drown themselves and een when those that try to drown themselves have rational reasons for doing so..as noted.

It is only the apprehension of value that requires some mind to apprehend it (lol..and this, only maybe - some thing without a mind might also be able to do so..idk). Not the existence of value. Your personal apprehension, thus, may be meaningfully subjective. Existence, not so much. Even the existence of that apprehansion isn't subjective by the criteria that moral theorists are discussing. It, too, exists, and isn't some artifact of our imagining it thus.

Do you value it..maybe not. Is it valuable. Yes. Do you see it? Maybe not. Does it exist? Yes.

---

It;s important to keep in mind that value objectivism is in no way shape or form a claim that there are no subjective values or valuing...whereas value subjectivity actually is the claim that there are no objective values or valuing.

The one can allow for both, while noting that not all values and valuing are alike. The other simply cannot..and must instead assert that all values and valuing, that certainly seem disparate, are in fact all the same. This leaves us in an odd position..most people focus on the fact that this would mean that no value is true value..it also means that no value is false value. Can you spot the paradox? All value statements are thus equally. Oxygen and candy bars are just as valuable as each other. The statement "Oxygen is more valuable than a candy bar" is in a subjectivist sense true..but so is "candy bars are more valuable than oxygen".

Kind of a pickle...and it doesn't seem to adequately describe the relationship here in reality, between ourselves, oxygen, and candy bars. Value objectivism states, otoh, that fact and value are relational..that while it;s certyainly possible for there to be a meaningful subjectivist value statement that is, on it's own terms, true, a meaningful objectivity is also possible.