(1) Non-naturalism as the default position: other positions enter the field on the strength of some argument
First Reason: Moral or normative language behaves in the similar way other representational language do. We assert or deny some moral issues. We are happy to assign truth values to sentences containing normative language. Of course, language might deceive us, but if so, the representational feature of moral language must be the default position.
Second Reason: Moral discourse exhibits objective purport. Even if we know that somebody's moral stanrad is different from others, we might criticize other's views or revise our views. Also, we have the intuition that certain counterfactuals deny response-dependence accounts of morality (Even if nobody acknowledged its wrongness, burying is wrong).
Thid Reason: Moral facts or properties seem to be not natural. Paradigmatically moral facts are so different from paradigmatically natural properties. Perhaps there are some borderline cases, such as being healthy, the heart's function of pumping blood. Perhaps, due to the presusse of some argument, we have to conclude that some moral properties are in fact natural, but still, we can say that moral facts' being non-natural is a default presupposition.
Fourth Reason: Moral facts seem to have full blood normativity (McPherson 2012). Whenever there are relevant criteria of correctness, normativity is present. Moral facts are not normative in this sense. Whether or not we set up the correctness of morality, the normativity of morality should be there (at least before we start our investigation).
(2) Some typical objections:
Naturalism: if metaphysical or methodological naturalism is correct, non-naturalism must be false.
Supervenience/ the Metaphysical Dependence: the supervenience of the moral on the non-moral requires some explanation, but the non-naturalism might face a difficulty of providing such an explanation.
The Epistemological Worry: how can we have the epistemic access to such non-natural facts/properties?
Evolutionary Debunking Argument: given the biological origine of moral judgements, we cannot assume the reliability of moral judgements as realists in general presuppose.
Meta-semantic: if moral properties are non-natural, how can we even have beliefs or concepts about them using moral terms? (ex., Moore's open question argument and the moral twin earth objection can be read as semantic objections to naturalistic moral realism, and remember Boyd's response to them, Boyd's semantic story looks more natural then the one the non-naturalist can offer)
Moral motivation: moral judgements and motivation seem to have a strong relation, but non-naturalism cannot explain this relation.
Why be moral challenge: if moral truths are completely independent of our concern, why do we care such things?
* A related issue Enoch takes up in his 2011 book: Reason for Action, non-naturalism faces a difficulty of explaning our reasons for action in general.
Moral disagreement: non-naturalism faces a difficulty of providing a satisfactory explanation of the phenomenon of moral disagreement. Contrary, the anti-realist might provide an abductive argument agasint realism appealing to the existence of actual moral disagreements (cf., Mackie 1977, Enoch 2011).
(3) Exactly, what is the view?
- Because of the creeping minimalism problem, the distinction between realism and anti-realism is getting unclear, and this state makes non-naturalism unclear as well (but this is not a problem particularly for non-naturalism).
- The quietist views: some non-naturalists who try to not to have heavy metaphysical commitment, such as Dworkin and Parfit (should they categorize them as non-naturalist realists, at all? do we need to do some 'meta-metaphysics'?).
- The issue concerning the natural-non-natural distinction: causal efficacy? (Oddie 2005 would disagree), empirical? (well, but we are doing metaphysics, not epistemology), non-normative?, the properties the empirical sciences quantify over? (Sturgeon 2007)
(4) Positive arguments for naturalism?
- the open question argument??: the original argument fails due to familiar reasons (even if a question is not closed, this does not imply that there is an identity, etc.), but some lessons may be taken, such as that natural facts do not have the moral normativity, that moral facts and natural facts are so different and the reduction is hopeless.
- some analogy? : Cuneo (2007) gives an analogy between epistemic norms and moral norms, and argues that because epistemic norms should be understood in terms non-naturalistic realism about epistemic norms, we should also understand moral norms in the same way.
- good first-order implication? (Enoch 2011)
- necessary for the deliberative project? (Enoch 2011)