An excellent and thorny question. I’ll try to clarify.
First, I would distinguish between “personal” and “human.” Values or preferences are presumably based on beliefs about what’s good or right or what matters. I can form beliefs like this about what’s good for me only – for example if I like the taste of chocolate, then chocolate ice cream is good for me (up to a point). Nothing about what’s good for you follows from that – you might prefer strawberry.
But these are just contingencies. The question is what’s truly good, truly praiseworthy, objectively valuable. What should we like, esteem, strive for? This is a question that we pose in the first person plural, not the first person singular, because it pertains to human beings and the human condition as such. Answering this question requires us to employ a concept of what’s objectively or intrinsically good, not just what this or that person regards as good as a matter of fact.
I arrived at this position in part because the alternatives strike me as absurd. If what’s right and wrong or good and bad are merely subjective, then it must have been right to burn witches in the 17th century but wrong to do so in the 20th. Slavery must have been good until we decided it was bad. If values are subjective, someone who devotes his life to amassing the biggest tin foil collection in history is doing something as praiseworthy as what Michelangelo and Shakespeare did, if only he believes it to be.
To say that doing something of value means doing something that seems to the one doing it to have value confuses the interest we have in living a life that seems valuable and the interest we have in living a life that really is valuable. If you suspect that this is a distinction without a difference – that a valuable life just is a life that seems valuable to the one living it – consider Robert Nozick’s thought experiment in Anarchy, State, and Utopia. You’re offered a chance to have your brain removed and hooked up to an Experience Machine that will provide you with the illusion that you’re living the best life you can imagine. In reality, you’re a brain in a vat, but you won’t know that – so far as your subjective experience goes you’re writing symphonies, founding companies, winning elections or wars, or doing whatever else seems valuable to you. Should you accept the offer? Most of us would say no, but the question is why, and at least part of the answer is that subjective experience is not all there is to value.
Or consider two possible worlds. In World 1, you’re in love with X, X is in love with you, and both of you are happy. In World 2, you’re in love with X, but X hates you, wants you only for your money, and constantly cheats on you, but, because you’re unaware of this, your experience is exactly the same as in World 1. If it doesn’t matter whether your subjective experience corresponds to objective reality, then there’s no reason to prefer World 1 to World 2. Yet World 1 is obviously superior to World 2. Why? Because subjective experience accords with objective reality. In World 1 you don’t just think that X is in love with you, X really is in love with you.
Or consider Sisyphus, the very model of a life devoted to valueless activity. Imagine the gods arranged things so that Sisyphus believed that spending eternity pushing boulders up a mountain was the most valuable thing he could do. Would Sisyphus’ situation be no less absurd? If not, then subjective perceptions of value can’t be all there is to determining what counts as valuable. There must be a dimension of objectivity as well.
Now these considerations apply to groups as well as to individuals. Imagine that the gods made everyone believe that boulder-pushing was the greatest accomplishment possible, so that Sisyphus’ entire community shared his belief that he was doing something valuable. Would that make it so? If individuals can be wrong about what’s valuable, so can groups of individuals.
For these and other reasons, I don’t think we can avoid the concept of objective value. In determining what’s truly praiseworthy, we’re asking neither about what this or that individual values nor what members of a group agree is valuable – even if this group includes every human being who has ever lived or will live. In this sense, what’s valuable isn’t reducible to “human/personal valuation standards.” The important question is whether our valuation standards pick out what is truly, intrinsically, objectively valuable.
Note that none of this implies that we can know for certain what is in fact objectively valuable. The question of how and to what we apply the concept of objective value hasn’t been touched in anything I’ve said here. Perhaps disputes about the application of the concept will never be resolved. But such disputes make sense only given our commitment to the existence of objective values – if there weren’t any objective values, there would be nothing to dispute and no point to the dispute.