[Aquinasfan]

All acts are instrumental, and therefore are tools. Even unvoluntary acts, like sneezing or twitching, are instrumental, the first to respiratory, the second to muscular functioning. If somebody runs away with the money from the bank holdup, it serves his purpose [to get money]. To catch and punish him serves not his purpose, but ours. For him getting caught is not "a good". For us caching him is. That's why it is much better to use a framework in which the word "good" does not even enter. It does not have to be im-moral, just a-moral.

Goodness = utility. Good so far, but keep going.

Is the act of believing this truly good, or only instrumental for you? It must be the latter since "all acts are instrumental."

Since goodness reduces to simple utility, this belief is of use to you, but it may not be of use to others. So this belief has no objective utility or "goodness."

Your belief statement rises only to the level of a statement like, "I itch," a feeling of yours that's of no consequence to others. Neither is the statement a claim about objective reality. It's solipsistic.

[GSlob]

If I itch, what the [insert an expletive] do I care about others, unless I were to use them as itching posts, in which case they would be good to my purpose? The whole idea of "truly good" is absurd. Whatever is considered "good" is socially, or otherwise, conditioned, and conditional. And it is not even subject to majority voting, for remember that muslims or confucians outnumber the westerners. What they see, or can see, as "truly good" does not always coincide with your worldview. No reason to abandon it, though. One could hold on, and defend, one's worldview on purely subjective, selfish grounds - and defend, and hold on, to it no less effectively.