You spent 4 paragraphs reasserting the position that there are no moral truths. Instead, you assert (without argument) that moral talk is just a heuristic for some sort of conventional "social game" because it serves as a "useful fiction" (but "useful" for what? notice that terms like "useful fiction" or "orderly" often strongly smell like they're embedding evaluative content, depending upon the context). In any event, I'll charitably assume that you think moral language sincerely embeds no propositional content whatsoever.

Well, just to be clear: I for one am claiming moral language is not just conventional talk. When I say it's wrong it boil someone's child alive for pleasure, I'm asserting it as a propositional fact, with the same truth-status as a statement like "there exist red cars", or what have you.

Maybe you think I am the only one who does this, and that most other people don't think of themselves as asserting truths when they speak morally. But there's a mountain of linguistic evidence to the contrary:

1. Moral statements take the form of declarative sentences (as opposed to imperatives, questions, or interjections). Statements like "pleasure is good" have the same grammatical form as "weasels are mammals", and sentences of this form are those used to make factual assertions in other domains.

2. Moral predicates can be transformed into abstract nouns, suggesting they are intended to refer to properties. We talk about "goodness", "rightness", and so on. Again this points to moral realism in our language usage.

3. We ascribe to moral statements the same sort of properties that we do to other truth-bearing propositions. You can say "it's true that I have done something wrong in the past", or "it is false that torture is morally good". Of course, "true", "false", and "possible" are predicates that we apply only to propositions. No one would say "it is true that 'ouch!'", "it is false that 'shut the door'", or "it is possible that 'hurray!'". Again: more evidence that moral talk isn't just some sort of conventional game, but is in fact propositional.

4. Propositional attitude verbs can be prefixed to moral statements. We can say "George believes that the war was just", or "I wish we had more moral laws", or "I wonder whether I did the moral thing". In contrast, no one would say that "Jon believes that ouch", "I wonder whether please pass the salt", or "I hope that hurray for the Broncos!". The obvious explanation is that mental states such as believing, hoping, wishing, and wondering are by their nature propositionally focued, and of course moral statements are propositional (in that they refer to things which take objective truth values).

5. Moral statements can be transformed into yes/no questions. One can can assert "is it true that it's bad to murder?", but one cannot assert "Hurray for the Broncos?", or "Shut the door?". Of course this is because yes/no questions require propositions, and moral statements are propositions that take truth-values.

6. One can combine imperatives and emotional expressions with things that are characterized morally. E.g. "Do the right thing!", or "Hurray for virtue!". Consider a more complex example even: "We shouldn't be doing this, but it feels good, so let's do it anyway". This is perfectly intelligible if you believe that moral statements are propositional, but it's not if, e.g. "We shouldn't be doing this" expressed merely an emotion towards a proposed action or an imperative not to do it.

Let's summarize. Each of the following sentences make sense:

- I am questioning this act's rightness.

- It is true that pleasure is good.

- I hope I did the right thing.

- Is murder wrong?

- Do the good thing.

- If pleasure is good, then cake must be good.

None of these sentences make any sense if moral statements aren't actually propositional/truth-bearing. Therefore, the idea that moral language is just a conventional way of expressing emotions, or encoding some sort of conventional social game is highly implausible.

I have to stop the conversation here, but I will end it with this: do you have an argument for why you think moral statements aren't propositional? If so, ask yourself why that argument couldn't be applied to other domains as well.

My main point is that it is really hard to be nihilist about moral facts without also being one about other sorts of facts as well. Most of the arguments for moral nihilism can be re-adjusted and applied straightforwardly to, e.g., scientific nihilism. (For example, what if I asserted that "scientists aren't actually speaking about true and false theories, they're just playing a conventional game with each other because it serves as a useful fiction"). But almost no one wants to be a scientific nihilist (because that's also insane). So either you should be a nihilist about everything, or a nihilist about nothing (broadly speaking).