How Does The Naturalistic Realists Explain Ban On "Mixed Worlds"?

Many moral realists use moral supervenience as a premise for argument,and claim that the supervenience of moral quality to natural states is a conceptual truth.In this way,refuting the conceptual truth of moral supervenience becomes a counterargument strategy against the realists.For example,the anti-realist Simon Blackburn,he pointed out that for to tell which moral quality results from a given natural state is called "ascriptive supervenience",even if moral supervenience is a conceptual truth,the criteria for attributing moral qualities cannot be obtained through conceptual analysis,as there is no unified criteria for attribution.And then came "mixed worlds"."Mixed world" means that in one possible world that have the same natural states,but have different moral qualities."Mixed worlds" not only destroys the conceptual truth of moral supervenience,but also makes moral judgment lose the normalization.One of the challenges faced by realists is that they cannot reasonably explain ban on mixed worlds.Based on this,Blackburn proposed a proposition of anti-realism,projective theory,which on grounds of economy,of metaphysics,and of the theory of desire and action.And in the metaphysics argument of projection theory,he proposed a reasonable explanation for ban on mixed worlds,thereby proving that anti-realism is superior to realism.Realists have two main approaches of responding to Blackburn.The first is to deny the conceptual truth of moral supervenience,arguing that the moral quality necessary supervenience on the natural states is only metaphysical.Or advocate discussing supervenience only in a single possible world,thereby avoiding the criticism that "moral supervenience is a conceptual truth".The second is to deny that realism needs to explain ban on mixed worlds,arguing that attribution to moral quality is an empirical issue,not a conceptual possibility.The central idea of these two approaches of responding is to separate the discussion of "moral supervenience is a conceptual truth" from "explain ban on mixed worlds".If realism advocates only one of the two,they can resolve Blackburn’s criticism.However,Blackburn’s argument precisely combines the two.He believes that realists cannot explain ban on mixed worlds on the premise of moral supervenience is a conceptual truth.Therefore,neither of these two approaches can count as a successful response to Blackburn’s criticism.In my opinion,Blackburn first refuted the realist from the issue of moral attachment in the metaphysics argument of projective theory.Then,in the argument of theory of desire and action,he explains how projective theory ensures the normalization of moral judgments.Therefore,I believe that a realist’s response should include not only the two points mentioned above,but also an argument for normative issues.Moreover,the realist’s response must conform to Blackburn’s argumentative strategy.In order to find a feasible response for realists,first of all,I will summarize Blackburn’s argumentation strategy into three steps:(ⅰ)under the premise of advocating that moral supervenience is a conceptual truth,make a reasonable explanation for ban on mixed worlds(ⅱ),and ensure that moral judgments are normative(ⅲ).Moreover,the three flaws in Blackburn ’s argument-the failure to refute the "mixed world" under the "global supervenience",the solution to"fractured attitude problem" includes "mixed world",and in the justification of argument of the theory of desire and action,there appears "mixed world" of normalization-are transformed into available resources for the response of realists.Based on the above analysis,I will find a possible response for naturalistic reductionist among realists by drawing on the three shortcomings of Blackburn’s projective theory argument and following the three steps argumentation strategy he adopted.First of all,on the basis of reductionism,I will clarify the definition of "global supervenience".Later,I will use the proposition of reductionism to explain ban on mixed world,and explain the normalization of moral judgment through the "social point of view" of naturalistic realist Peter Railton.That is,naturalistic reductionist can reasonably explain ban on mixed worlds and the normalization of moral judgment,based on the premise that moral quality global supervenience on natural states is a conceptual truth.