The arguments from various species of scepticism, I believe, are sufficient to demonstrate that no such claim can be made with regards to any particular domain of truth.
You appear to be endorsing (or perhaps presenting for argument's sake) not only moral skepticism
, the view that there is nothing right or wrong independent of human opinion, but also global skepticism:
the view that there is no objective truth at all. This is an interesting approach. Let's combine global skepticism and moral skepticism into one schematic argument:
P1: If global skepticism is true, then moral skepticism is true.
P2: Global skepticism is true.
C. Therefore, moral skepticism is true.
Though (P1), as a bi-conditional statement, is certainly true, since global skepticism logically entails moral skepticism, (P2) is false. Why? Let's investigate.
Global skepticism is the view that there is no objective truth at all, anywhere. Moral skepticism is just the specifically ethical application of this wholesale doubt. If there is no objective truth, there cannot, obviously, be any objective moral truth. Many people find such an argument appealing. Their attraction to global skepticism is usually conveyed in something like the following terms: reality, it is said, differs from person to person (or culture to culture). What is true for me needn't be true for you. Before we came upon the scene, there was no truth. We don't just dictate what's good or evil; everything, every truth, is a product of human investment and creativity.
Why do people say such things? There are several reasons, but perhaps the most prominent one stems from puzzlement people feel at trying to identify a uniquely correct perspective from which to view reality. This isn't a silly worry. But even if we fail to remove such puzzlement, this shouldn't lead us to take up global skepticism. People might have absolutely irreconcilable differences about the origins of the universe, about whether there is some essential difference between male and female natures, or whether abortion is immoral, and yet there can be, despite such differences, some objective truth that awaits our discovery on each of these issues.
That's just a promissory note, however, since global skepticism is itself an indefensible position. Why? It's self-refuting. An absolutely fatal flaw remains for those who base their moral skepticism on their allegiance to its cousin, global skepticism. And that fatal flaw is that global skepticism is self-refuting. Let's see why.
Suppose someone is a moral skeptic because he endorses global skepticism. There are no truths at all
. That's why there are no moral truths. But if there are no truths, then what of the global skeptic's claim, that there are no truths at all? If there are no truths at all, then global skepticism itself cannot be true. If we correctly apply the theory, it turns around and undercuts its own authority! If global skepticism is true, then there is at least one truth, and that is contrary to the claim that global skepticism makes. Being self-contradictory, it cannot be true.
Since global skepticisim cannot be true, it cannot serve as a plausible basis for anything, much less moral skepticism. Something else might, but not it. After all, if moral skepticism is true, then there is still at least one truth (i.e., moral nihilism
). And that still contradicts global skepticism. So moral skeptics do best to look elsewhere for support.
Bear in mind that a similiar story can be told for both global subjectivism
and global relativism
. Suppose you are a moral subjectivist
because you have become convinced of global subjectivism--the idea that truth in every area is in the eye of the beholder. If global subjectivism is true, then subjectivism about ethics must be true as well. But what is the status of global subjectivism? Global subjectivism really amounts to the following view: a claim is true if, and only if, I believe it. Suppose global subjectivism is true. Now also suppose that I don't believe it (I don't). I believe that I am mistaken about some things, even though I don't, at present, know just what they are. I recognize my own fallibility, and so reject the idea that something is true just in case I happen to believe it. I think that global subjectivism is false.
According to global subjectivism, a claim is true if I believe it. Yet I believe the claim: (1) Global subjectivism is false.
Therefore, if global subjectivism is true, then (1) is true, since I believe it. (1) says that global subjectivism is false. Therefore, if global subjectivism is true, then global subjectivism is false. Global subjectivism is not directly self-refuting, as global skepticism is, but once we add the true claim that someone (anyone) believes it to be false, then it contradicts itself, as we have just seen. Because it does, it cannot supply a plausible basis for moral subjectivism.
Relativism suffers a similiar fate. Global relativism
claims that all truth is relative to a society. More specifically, it claims that a proposition is true just in case it is endorsed as such by a society, or is implied by a society's fundamental commitments. According to global relativism, there is no objective truth; no truth independent of social endorsement, hence, moral relativism.
Global relativism, like global subjectivism but not global skepticism, is not directly self-refuting. But it must be false for any society that rejects it. And every society does. Consider a random sampling of predominant views held within U.S. society: the Earth is round, Winter follows Autumn, the Rockies are taller than the Appalachians. Does anyone believe that these true propositions are true just for us Americans? Or true only so long as we believe them?
By its own lights, global relativism must be false for those of us who are reading this and are situated in societies whose commitments imply a rejection of global relativism. If we correctly apply global relativism, then it can be true only if a society thinks it true. No society thinks it true. Therefore it is false.
The general lesson here is that any effort to reject objective truth is bound to undercut its own authority. If a theory denies the existence of objective truth, then the theory itself cannot be objectively true. If global skepticism is correct, then there is no truth at all, and so global skepticism cannot be true. If global subjectivism is correct, then it is true only if I believe it to be. If I don't, then it's false. If global relativism is true, but my culture rejects it, then it is false. If we correctly apply these theories to themselves (which is only fair), we find that each theory, if true, implies its own logical falsity.
Indeed, none of this demonstrates that moral
skepticism, or moral
subjectivism, or moral
relativism is false, but using their self-contradictory or implausible global
cousins as support for them leads to intractable problems, as we've seen. Therefore, moral skeptics of all stripes should rethink their strategy and look elsewhere for a knock-down argument against moral objectivism.
Logically speaking, the falsity of (P2) doesn't demonstrate the falsity of (C); that is, (C) could still
be true by way of some
argument, but not by way of the argument from global skepticism. You'll need to work with moral skepticism from the ground up, without reference to global skepticism, in order to argue against moral objectivism.
In particular, you (or anyone) could undertake this meta-ethical project against moral objectivism by arguing for one of three views:
(1) Moral Nihilism:
the view which claims that there is nothing right or wrong; alternatively, the view that there are no moral truths. The two kinds of moral nihilism are error-theory
(1.1) Error theory:
the kind of moral nihilism which claims that moral language tries, but always fails, to accurately describe moral reality (because there is none to describe).
the kind of moral nihilism which claims that moral language does not attempt to describe anything, but instead is used to persuade, encourage, prescribe or be expressive of one's feelings
. As such, moral judgments cannot be true or false.
(2) Moral Subjectivism:
the view which claims that an action is morally right if and only if one approves of it, and a moral judgment is true if and only if it accurately reports the sentiments of the one who holds it.
(3) Moral Relativism:
the view which claims that an action is morally right if and only if it is permitted by the ultimate conventions of the society in which it is performed, and a moral judgment is true if and only if it is endorsed by the ultimate conventions of the society from which it derives.
I'm prepared to defend...
the view which claims that there are correct moral standards, and that these standards are true independently of what any society, or anyone, anywhere, happens to think of them (i.e., objective).
...against all three.
There is one more argument open to you, and one which I think best matches your earlier thoughts: epistemic moral skepticism,
which refers to doubts about the possibility of moral knowledge
, rather than to doubts about the ontological status
or existence of objective moral truth. There can be those who are skeptical in both ways, of course--moral nihilists who, since they reject the possibility of moral truth, also reject the possibility of moral knowledge. But one might reject moral nihilism, or be neutral about the existence or nature of moral truth, and nevertheless insist that even if there is any, we cannot know
it. This latter sort of view, known as epistemic moral skepticism, is also available to you. I'm prepared to defend moral objectivism against it as well.