Re-assessing the moral realism debate
What have I actually proved by my argument in favor of moral realism?
It seems to me now that what I have actually proved is neither the direct truth of realism nor the direct refutation of relativism. I have in fact shown naturalism to be self-contradictory, and it is this refutation of naturalism that has significant things to say about the realism/relativism debate, and the debate is not as quite settled as I had initially believed. (I take naturalism is the belief that the only facts we should accept are the ones that are endorsed by and/or compatible with science.)
I have also shown that for knowledge to be possible, intuitions have to be valid (Butters pointed that out in the comments, actually). However, for rational knowledge to be possible, only rational intuitions have to be considered as having an objective validity. It appears that it is possible to maintain that only rational intuitions have objective validity while moral intuitions do not. i.e. the falsity of naturalism and moral relativism are possibly compatible.
It seems really odd to me to uphold the view that our intuitions developed in such a way that one type of intuitions (rational intuitions) turned out to have objective validity, while the other type of intuitions (moral intuitions) turned out to be completely deluded. However, given the truth of rational intuitions and falsity of naturalism, let us see what reasons can be offered in support of this asymmetry between rational and moral intuitions:
i) The extent and depth of moral disagreement is far more than the extent and depth of rational disagreement.
ii) Moral Internalism holds that moral convictions necessarily have a motivating effect on the person holding the convictions. This can be used to argue that moral convictions are bound up with motivation because they are in fact expressions of 'motivational states of desire, approval, or commitment (that might be satisfied or frustrated but are neither true nor false)'*
i) Moral Disagreement
I think there is a definite misperception regarding the disagreement in moral matters, and it is seen to be more exaggerated than it is. I personally think that many, if not all, moral propositions based on moral intuitions have a two degree structure.
First Degree: It is wrong to do X/right to do X, unless there are good reasons to do otherwise.
Second Degree: The intuitions regarding what those good reasons are or are not.
First Degree: It is wrong to inflict cruelty, unless there is a good reason to do so.
Second Degree: Inflicting cruelty as a punishment for crimes is a good reason.
First Degree: It is wrong to kill anyone, unless there is a good reason to do so.
Second Degree: Killing someone in the process of self-defense is a good reason.
First Degree: It is wrong to steal, unless there is a good reason to do so.
Second Degree: Stealing to prevent death from starvation is a good reason.
Now, the First Degree Intuitions are almost universal, while the Second Degree Intuitions are not quite universal and genuine disagreement can exist. Therefore, all those matters of moral disagreement which have this two degree structure, the disagreement is not as extensive nor as deep as to be used as an argument against realism.
Apart from this, there are other explanations for moral disagreement consistent with moral realism. These include:
# Some apparently moral disagreement are actually disagreements on non-moral issues. ('the explanation of moral disagreements will be of a piece with whatever turns out to be a good explanation of the various nonmoral disagreements people find themselves in.'*)
# Individual emotions and interests can distort the perception of moral truth, leading to disagreement.*
Therefore, moral disagreement as it exists is not an argument in favor of implausibility of moral intuitions, and there is no reason to support the asymmetry between rational and moral intuitions.
ii) Moral Internalism
There are two answers to this. First is the Moral Externalist claim that not all moral claims are intrinsically motivating. Externalists believe that there is nothing logically necessary about the conjunction of moral claim and motivations, and that moral claims can exist without motivations. So while internalism may be true, there is no real argument to show that it is true, and in the absence of that, it cannot be held as an argument against non-validity of moral intuitions. Secondly, it can be shown that there are non-moral claims that are bound up with motivations. Such as, the experience of being in pain is intrinsically bound up with the motivation of avoiding that pain. Therefore, moral internalism, even if it is true, is no argument in itself for the non-validity of moral intuitions.*
Conclusion: It is obvious to me now that the realist/relativist debate is not quite as settled as I had the initial impression, but I believe, with reasons explained above, that it can be confidently argued that the debate tilts far more in the favor of moral realism, and there is no genuine argument to suggest that there should exist an asymmetry between the objective validity of rational and moral intuitions.
* The references are from Stanford Encyclopedia of Philosophy.