Chalmers’ The Conscious Mind is amazing. Among other things, it seems to touch upon, and provide us with, a novel view of practically every important area of philosophy.

In regard to the metaphysical status of moral and aesthetic properties [pp. 83-84]

Chalmers holds, or at least suggests:

(1)   There seems to be no “…conceivable world that is naturally identical to ours but morally distinct, so it is unlikely that moral facts are further facts in any strong sense.” (p.  83)

(2)    “…moral facts are not phenomena that force themselves on us. When it comes to the crunch, we can deny that moral facts exist at all.” (p. 83)

He offers an argument against the idea “…that moral facts supervene on natural facts with A POSTERIORI NECESSITY..” (p. 84)

“…even A POSTERIORI equivalences must be grounded in A PROIRI reference fixation. Even though it is A POSTERIORI that Water is H2O, the facts about water follow from the microphysical facts A PRIORI. “(p.84)

The section ends:

“Aesthetic properties can be treated in a similar way. If anything, an antirealist treatment is even more plausible here. In the final analysis, although there are interesting conceptual questions about how the moral and aesthetic domains should be treated, they do not pose metaphysical and explanatory problems comparable to those posed by conscious experience.” (p. 84)

I hold (with a feeble grasp) that there are genuine irreducible objective moral facts (and properties). On the other hand, I am prepared to admit that I may be wrong. Perhaps those who regard the moral realm as a human construct are right. I guess this commits me to holding that there is an epistemically (i.e. logically) possible world that is physically exactly like the real world but in which there is no such thing as a positive irreducible absolute moral fact. If I am right, then, it looks as though this permits me to use a Chalmers like argument to persuade myself that some moral properties are ‘further facts’ in a strong sense.