Typical moral objectivity is the claim that morality exists independent of human beings, it is already part of the fabric of the universe. There are three popular arguments used against such a position, we will here examine these arguments skeptically. These arguments are, in descending order of popularity: "The Argument from Lack of Agreement", "The Argument from Relativity" and "The Argument from Queerness". Let us see if they any of them are acceptable to a skeptic or not.
The Argument from Lack of Agreement
From the fact that it seems that we cannot reach universal agreement (where everyone agrees)- on points of moral issues such as abortion, euthanasia and so on, this concludes that this is because there are no moral facts of the matter - there are no empirical objective moral facts and this is why people disagree. An extreme version of this would be that it takes only one dissenting voice on an issue to lead to this conclusion. However even where there are empirical objective facts there is still no universal agreement - look at creationism and global warming. Given these and numerous other situations given the fact that there is disagreement one cannot conclude that there are no empirical objective facts. Anyway this argument is self-refuting since, for the reasons given, I disagree with it and so we could no not reach universal agreement that this is a sound and valid argument! For more see my post The argument from lack of agreement.
The Argument from Relativity
This is based on the descriptive observation that moral codes vary from country to country, within different levels of individual societies and have changed over time. Not only does the content vary but also how the codes work - by laws, rules, informal guidelines, precepts and so on - and how they are explained - given by god's commands, built into god's nature, natural laws, rational laws, Karma and so on. Why would this be if there were empirical facts of the matter, why has there been no convergence?
Well, on the other side, one can chose to look for similarities rather than differences. Then one can see a broadly similar set of core principles across cultures. The differences - the variations in how they vary in scope (to whom they apply) and in the types and gravity of penalties and sanctions -`can be explained by society's specific extra-moral beliefs - their super-naturalistic and strange beliefs and myths - and by the environmental, ecological and economic history and current situation of that society. One could also argue that there is convergence now, we are in a global world and have the Universal Declaration on Human Rights. Different groups might be resisting this and its improvements, but convergence is on the way.
Well anyone who has engaged in moral debate has probably been on one side or another of this argument - either emphasizing the difference (the similarities being secondary) or the similarities (then the differences being secondary). What one can say, at this stage of our investigation, is that this argument is insufficient to support the conclusion that there are no empirical objective moral facts of the matter.(I will post more on relativism in the future).
The Argument from Queerness
This is most popularly stated as in: What are these things called Goodness, Badness or Evil? Can I see them? Taste them? Touch them? Hear them? They are invisible to our senses. Empiricism is based on what we can sense about the world and our senses can be instrumentally extended beyond their human limitations using microscopes, telescopes, computers and so on. Whatever instruments we use to extend the reach of our senses - empiricism as normally understood - we still cannot detect the supposed essences or properties of goodness, badness and evil. We can measure all sorts of properties of objects and even actions - their mass, force, light reflectance but still we cannot detect such properties and if they existed they would be quite unlike any other property (primary or secondary) that we are familiar with - they are "queer". From this, one concludes that there are no empirical objective moral facts - that such facts would be queer in the sense that there are no precedents from anywhere in the enormously successful systematic empirical enterprise that we call science, that could used to explain or indicate what these properties are, how they work and whether we could detect them or not.
The main counter-argument to this would appear to be this is an argument from ignorance, but unless someone can demonstrate a reliable, repeatable way how to find and show these essences or properties independent of particular human views, beliefs, opinions or intuitions, this counter-argument has no force. The best we can say now is that until a solution is presented, we can provisionally conclude that empirical objective moral facts do not exist.
We have examined the three main arguments against moral objectivity (independent of human subjectivity). The first argument "The Argument from lack of Agreement" is useless and should be dismissed. The second argument "The Argument from Relativity" might be persuasive to some but not to others and is, for now, insufficient. The third argument "The Argument from Queerness" is, so far, the strongest argument and the only one a skeptic would deem sufficient to use in investigating specific claims and types of moral objectivity. We now have a tool to examine the main variants of moral objectivity next, the tool being this argument.