Many rational minds have come to attribute the foundation of morality to humankind's survival and happiness. I have been discussing with friends about why that 'humankind survival and happiness' must or should be the ground rule of judging a system of ethics or morality. We came to the conclusion that it's only an arbitrary preference of humankind. Are there any other factors to take these ground rules as a basis of morality, including objective factors?
This is a very, very simple problem: morality is a code of conduct decided by human beings on the basis of our sense of fairness.
Any community of humans needs a code of conduct simply to be able to function efficiently as a community. Without a code of conduct, everything goes and people simply revert to naked physical violence to settle their personal conflicts of interest, which history has shown is not a very effective way to do things. All communities adopt, one way or the other, a code of conduct. Most codes of conduct are somehow unfair and biased in various ways in favour of some members of the community, and this leads to violent conflicts. This in turn leads unsurprisingly some people to argue that the code of conduct that happens to favour them should be preserved, while those who suffer unfairly from a code of conduct will want to change some aspects of it., which overall leads to an evolution in the codes of conduct. In a few thousand years, we moved from tribal codes of conduct that included human sacrifices to democracy and human rights. There is no reason to believe that our current code of conduct is perfectly fair, so it is only natural that it will continue to evolve.
What is fair? The notion of fairness is essentially a natural one. All gregarious animals have a sense of fairness: humans but also wolves, rats, monkeys, elephants etc. Essentially, our sense of fairness is the product of natural selection, broadly over the 60 million years of the evolutions of all mammal species, including humans. Our sense of fairness may be regarded as a proto-code of conduct produced by natural selection. Gregarious species had to have one to survive, reproduce and prosper. Those that didn't evolve a sense of fairness simple didn't become gregarious.
So, as humans we start with our sense of fairness inherited from our ancestor species, and there is nothing we can do about it. Like logic and sex, it is hardwired into our DNA. It is our nature.
Our codes of conduct are in effect merely the rules which are necessary for human communities to function as communities given that humans modify their own environment very quickly. Our codes of conduct are the necessary adaption of human communities to their own way of life and its impact on the environment. You need a specific code to sustain a particular way of life. In a changing environment, and our environment is always changing because we ourselves change it, communities have to adapt their code of conduct if they want to survive.
This is all there is to morality.
Is the purpose of a fire to require more fuel? Having fuel is a precondition of having a fire, and it continuing to have fuel is a precondition of to remain a subject for discussion. Similarly for survival - it's a precondition, we had to have that bias to have got here, to have evolved. But we know humans can & do choose not to survive - & sometimes we call that the summit of the moral life, sacrifice for others. In antenatalism & efilism people have gone further, suggesting creating new life is immoral, because it causes suffering - net-unhappiness would make life unjustifiable, if you make happiness it's purpose.
Happiness is not a thing. Utilitarianism wrestled with this, trying to quantify it with various types of ranked pleasures, hedonic calculus, and so on. It leads to many problems & paradoxes, like a 'super maximiser' experiencing sublime states getting to exploit everyone else (of course, we do this to animals, and have done to slaves, which should make us consider this carefully..). Peter Singer has shown a kind of capacities methodology, can help us be consistent in approaching ethical dilemmas, but many don't like where that leads in some cases like around disability.
Even purely as an individual, saying our purpose or meaning is happiness just substitutes words. We say whatever we decide to do or find meaningful, we do so for 'happiness'. And we can do no other - even suicide has to be pictured as seeking a kind of happiness in ending suffering. It's a tautology, to say we seek happiness, if happiness is pictured as just, the necessary result of getting whatever we do in fact decide to seek. Happiness as usually pictured is a compass direction, it can evaluate a kind of gradient between directions you could go in, but not why. This is Hume's is vs ought distinction again, however precisely you lay out how things are, including exactly why someone else should choose x, for 'happiness', it will be down to them, their impulses. And we say, as long as they can justify what they did in a court of law, and among their friends, and to themselves, that wasn't immoral. Even, if they all think it was crazy, self-destructive, inconsistent, etc.
Aristotle had an explicitly open-ended idea of happiness in eudaimonia, 'human flourishing'. Both fulfilling our natures, and reaching beyond them to develop what that is. If we explicitly set happiness in a wider understanding of human nature, eg what a wise and virtuous life is, we can say true happiness is our goal it will be fulfilled by living up to x understanding of life. But that will always be open to debate, & question, and a subjective personal journey to defining it. What is your 'flourishing'? How do you understand wise & virtuous?
However you square it, survival and happiness are not enough, even to really get started on how to be moral. We need a big picture about why. We need to look at actual behaviour. And we need personal engagement with these kinds of considerations, to find personally satisfying answers.
In short, we still need philosophy!
The foundation of morality is the knowledge of good and evil, which itself is based on the concepts of pain and pleasure <== and those two, sure, are 100% subjective experiences!
It is having them that's 100% not.
You, me, everyone share the knowledge, the same understanding of what it means to be in pain, what would put us ourselves in pain, and how we can hurt others. Which makes our knowledge of good and evil, and, ultimately, our morals just as universal.
We are not evil because we lack morals. If we commit evil, it's because we don't always know what we are doing. That's why knowledge is the only true virtue.
The most basic drive of any life form is for mastery of their environment, which generally translates to survival, individually or genetically. This is the same for a tenacious plant growing through cracks in a pavement, or a determined problem-solving human being.
Having solutions operating well engenders wellbeing and happiness.
Problems of social and ecological fairness are just more problems to be solved - albeit fundamental and often challenging.
The idea of fairness or proper behaviour in society is contained in the very definition of morality, (and the idea that it extends to proper behaviour in the ecosystem is a logical consequence of society's interdependence on the ecosystem).
For more info on 'life drive' see https://philosophy.stackexchange.com/a/75998/5154