But there's that language again that people use when they talk about moral nihilism, where I can't tell if they're just using different words, or if they really think that morality can be whatever we want it to be, or that it doesn't mean anything to say that moral propositions are true or false.
Okay. Correct me if any of this doesn't sound right. When a person talks about "morality", you imagine a conceptual framework of some sort - some way of distinguishing what makes actions "good" or "bad", "right" or "wrong", etc. Different people will imagine different frameworks, possibly radically so - but there is generally a lot of common ground (or so we hope), which is why you and I can talk about "morality" and more or less understand the gist of each other's arguments. Now, I would claim that what I mean when I say "morality", or what you mean, or what a reasonable third party may mean, or any combination thereof - that each of these is entirely unrelated to ground truth.
Basically, moral propositions (e.g. "Murder is Bad") contain unbound variables (in this case, "Bad") which are only defined in select subjective frames of reference. "Bad" does not have a universal value in the sense that "Speed of Light" or "Atomic Weight of Hydrogen" or "The top LessWrong contributor as of midnight January 1st, 2015" do. That is the main thesis of Moral Nihilism as far as I understand it. Does that sound sensible?
I wouldn't ask people those questions. People can be wrong about what they value. The point of moral philosophy is to know what you should do.
Alright; let me rephrase my point. Let us say that you have access to everything there that can be known about a individual X. Can you explain how you compute their objective contingent morality to an observer who has no concept of morality? You previous statement of "what is moral is what you value" would need to define "what you value" before it would suffice. Note that unless you can do this construction, you don't actually have something objective.
What you're proposing sounds more like moral relativism than moral nihilism.
I think that you're confusing moral universalism with moral absolutism and value monism. If a particular individual values eating ice cream and there are no consequences that would conflict with other values of this individual for eating ice cream in these particular circumstances, then it is moral for that individual to eat ice cream, and I do not believe that it makes sense to say that it is not meaningful to say that it is true that it is moral for this individual to eat ice cre...
I have noticed that the term 'nihilism' has quite a few different connotations. I do not know that it is a coincidence. Reputedly, the most popular connotation, and in my opinion, the least well-defined, is existential nihilism, 'the philosophical theory that life has no intrinsic meaning or value.' I think that most LessWrong users would agree that there is no intrinsic meaning or value, but also that they would argue that there is a contingent meaning or value, and that the absence of such intrinsic meaning or value is no justification to be a generally insufferable person.
There is also the slightly similar but perhaps more well-defined moral nihilism; epistemological nihilism; and the not-unrelated fatalism.
Here, it goes without saying that each of these positions is wrong.