Nihilists concede that morality is completely subjective because it's not rooted in science, but I disagree. Sure, there are clearly disagreements about whether certain things are moral or immoral, but for most things, there is universal consensus of what is right and wrong rooted within the human psyche. Rape, for example, is an example of an immoral act because it is an intrusion on a person's body without their consent; that is objectively wrong and any sane person knows this. Human nature is dictated by our consciences. That's why those without a conscience, sociopaths, are unfit to operate within a society of sane individuals.
Both. We have common grounds, but then it's subjective. Not only to the person, but also to the situation. Some people will say killing is wrong in all times, some will say sometimes it's right to have the death penalty, it depends imo.
Moral realism is the vast majority opinion held in ethics by professionals. Most ethicists and moral philosophers support the idea of objective morality than its alternatives (moral anti-realism, moral relativism, moral nihilism). The arguments for objective morality are more robust, convincing and efficient than the arguments for subjective morality.
We have common grounds, but then it's subjective. Not only to the person, but also to the situation. Some people will say killing is wrong in all times, some will say sometimes it's right to have the death penalty, it depends imo.