People make rational decisions all the time, relying only on the few evidence available to them. Sure we don’t have all the evidence, but that doesn’t mean there isn’t the choice that has the most possibility of a desirable outcome.
Also, what is the purpose of morality? Because if morality had any purpose at all, it would be objective. It’s like if I presented you with the numbers 1 through 5 and told you to pick 2 numbers that added together yield the largest number, there is objectively only 1 best answer to that question. If morality’s purpose was to please a sky-god, it would be objective.
If morality’s purpose is everyone’s mutual self interest (which it is), it would still be objective.
Even subjectively, morality is still objective. Because objectively there can only be 1 best subjective angle to take on the issue, and once you’ve know what that angle is, morality becomes objective.
Morality is objective, but it is not simple like “black and white”. Refer to your local state laws, ever wonder why its hundreds upon hundreds of pages? Because people figured out that 10, 20 or even 100 rules were barely enough to cover all the situations, so we wrote more and more laws containing our best guess at how to manage each specific moral conundrum. So what started as a simple “do not kill” evolved into “do not kill unless in self defense” and further involved into the 90 billion different types of legal and illegal killing we have today. Yet despite its sophistication and its ever evolving nature, morality is still objective.
Again, I urge you to look at it like a math problem, eg. what is 5×5? Early on in history, we thought the answer was 5. but then we figured the number had to be bigger. 6. 7. 8. and so on. Those were our best guesses, but despite all that evolving and improving, the objective answer has always been 25, we’re just getting closer and closer to it generally speaking.
Let’s approach this from another angle: instead of the question what is 5×5, instead if the question was what is nx5, would the answer still be subjective? After all, the answer is dependent upon the variable of “n” surely that would make it subjective, after all, the result is still subject to the variable.
No, it doesn’t, because whatever number you insert in place of n, there is objectively only one correct output. And whatever your answer is, it can only be one of the following:
correct (completely accurate), close to correct (somewhat usable), far from correct (barely usable), or plain wrong (unusable).
I mean, I guess the real lesson to be taken here is that subjectivity and objectivity in morality is not necessarily mutually exclusive. After all, the only way to produce objective morality is to subject our morality calculator to the host of variables and through that produce the right answers. I suppose in a sense, moral subjectivity could be the method to produce objective morality. It’s subjective, just not in the way you think, because even though the variables are subjective, there can only be objectively 1 best moral calculator and thus one best answer at any given moment.