This is the only way I have found out in my own thinking, so far, to fit an objective morality into a naturalistic, physicalistic, world-view. Since currently I sympathize with something along the lines of Searle’s theory of mind, which sees mental events as qualitative and physical at the same time, I have no problem in admitting into my naturalistic world-view what is called a «subjective, qualitative» state-of-affairs such as a pain or a suffering. Thus, I accept mental events as parts of our spatio-temporal reality: real mental events, qualitative and with a «first-person ontology» as is said nowadays, unlike the phony ersatz mental states of some eliminative materialists.
The first core idea is that some mental states are intrinsically, by their very nature, bad, undesirable, or negative. Mental states such as psychic exhaustion after prolonged and intense pain, or such as angst, depression, sadness, or the strong pains in themselves. (Dennett and Damasio have commented on compelling empirical evidence that pains are not intrinsically anguish-inducing, and if that is true then my theory is easily mended by noting that the mental state of anguish is intrinsically bad or negative or undesirable.)
The second core idea is that there’s nothing troublesome with stating that causing bad things, when one can avoid causing bad things (and thus has agency, a term I also understand naturalistically), is doing something wrong. (One could be more ambitious here and state that omitting help and rescue to someone who is suffering terribly or in grave danger of doing so is also to do something wrong, if you can help or rescue them. Maybe this could ground a positive duty, something you ought to do because not doing that something is, in a sense of ‘doing’, doing something wrong.)
Combining both ideas, one gets that it is naturalistically possible to do something wrong (and that people often do it), for the first idea shows us something both natural (physical) and bad exists — proving there are spatio-temporal normative facts — and the second one links the existence of bad things to the possibility of wrong-doing.
There are a myriad of very sad consequences, which is what keeps my gears grinding looking for better solutions. It seems unbelievable that:
(a) It is perfectly OK to rape, spy on, ridicule, or steal from someone if one was utterly sure that the victim would never realize they were raped, spied upon, ridiculed, or stolen from. Say, if you dope someone near the end of a alcohol-soaked party and rape them, making they wake up a few hours later thinking they’ve had too many drinks. Or if you install a hidden camera in the public bathroom to watch men and women showering, for your own private enjoyment. Or ridiculing someone behind their backs, to people whose actions don’t matter to that person and who won’t tell that person (or tell someone who tells someone … who tells that person). Or stealing someone who doesn’t pay much attention to their own money.
(b) It is perfectly OK to kill someone who greatly values their life, yet has no emotional bonds with any other person, if the murder proceeds without any pain, suffering, fear, sadness, and so forth. This is because killing them could only be wrong, in the slim naturalistic basis I have grounded morality upon, if it cause anyone some intrinsically bad experience, such as the ones listed on the previous sentence. Preventing intrinsically rewarding, pleasurable, and satisfactory — thus good — mental states wouldn’t be doing something wrong — i.e. the premature ending of a happy life wouldn’t be bad.
(c) It is perfectly OK to dedicate one’s free time in contemplation of New Age phony nuggets of wisdom, the writing of (what we would call) bad poetry (and hating on the poetry of Shakespeare), and enjoying the music of death metal bands (and hating on the music of Bach). In fact, everything is equivalent, morally-wise, when it comes to spending the time one has left after avoiding all omissions of help and bending backwards to prevent causing some suffering.