I agree, morality is not objective in any absolute or ultimate sense. However, moral codes do rely upon objectively verifiable physical and emotional responses to certain conditions, conditions which are likely to be common in social creatures that achieve or exceed our own biological and social complexity, regardless where in the universe they exist. That these are subjective experiences arguably strengthens rather than weakens the moral case for or against certain types of behaviour. I’ve argued the line between what we consider objective and subjective is not as sharp as we typically assume.
With that said, the following is a portion of my own argument regarding the subject of objective morality:
“In discussions of morality, extreme examples are often abused. There is a tendency to revert too quickly to examples like the Holocaust or slavery. In such instances, the nuance inherent within more day-to-day moral dilemmas — the sort with which most people can actually relate — are rarely if ever addressed.
With that disclaimer in mind, any test of either morality’s transcendent objective nature or its proximate and accessible qualities must be able to show at least one of these positions is workable under our worst case scenarios. If one or neither of these descriptions of morality works under the pressure imposed by situations of extraordinary cruelty, such as genocide and slavery, then that description(s) simply is not workable.
Let’s use slavery as our extreme example. According to those contending that an ultimate objective morality is necessary for anything to really be right or wrong, there can be nothing truly immoral about slavery in the absence of something like a supreme being dictating its wrongness to the universe, or, alternatively, a universal moral law that is analogous to the physical law of gravity. In other words, the wrongness of the act lies not in the suffering taking place on the plantation where slaves are toiling for long hours under the lash and a hot sun, but out there somewhere, where moral codes are written by god or nature.
If an advocate for an ultimate source of morality offers a single sufficient proximate reason for the wrongness of slavery, he has nullified his entire argument. There’s no need to go any further to justify his abolitionist stance. Let’s say he visits a slave plantation and finds it intensely emotionally distressing, and afterward offers this personal experience as evidence for why slavery must be wrong. It doesn’t get much more proximate than the nauseating sight of human torture and neglect on such a massive scale. If he says making people work against their will violates the Golden Rule which insists upon the rightness of treating others as we would be treated ourselves, and infringes upon their liberty to decide for themselves the work they are willing to do besides, he has now offered two more proximate reasons.
By gathering earthly evidence it can be shown that both of these reasons accurately reflect the feelings of others living both in and out of slavery, including even by the slave owners themselves — though they may be loath to admit it. The physiological and emotional damage associated with slavery and other forms of oppression can, with today’s knowledge and technology, readily be compared to the average physical and emotional health of populations living outside such conditions. The results of these comparisons only further strengthen the proximate case for slavery’s immorality.”