Moral debate per Alasdair MacIntyre

In After Virtue Alasdair MacIntyre asks, What salient characteristics do debates and disagreements about morality share? He says there are three kinds.

"The first is what I shall call, adapting an expression from the philosophy of science, the conceptual incommensurability of the rival arguments in each of the three debates. Every one of the arguments is logically valid or can be easily expanded so as to be made so; the conclusions do follow from the premises. But the rival premises are such that we possess no rational weighing the claims of one as against another. For each premise employs some quite different normative or evaluative concept from the others, so that the claims made upon us are of quite different kinds. In the first argument, for example, premises which invoke justice and innocence are at odds with premises that invoke success and survival; in the second,  premises which invoke rights are at odds with those that invoke universalizability; in the third it is the claim of equality that is matched against liberty. It is precisely because there is in society no established way of deciding between these claims that moral argument appears to be necessarily interminable. From our rival conclusions we can argue back to our rival premises; but when we do arrive at our premises argument ceases and the invocation of one premise against another becomes a matter of pure assertion and counter-assertion. Hence perhaps the slightly shrill tone of so much moral debate" (p. 8, pb). 

"A second, equally important, but contrasting, characteristic of these arguments is that they do none the less purport to be impersonal rational arguments" (p.8).

"A third salient characteristic of contemporary moral debate is intimately related to the first two. It is easy to see that the different conceptually incommensurable premises of the rival arguments deployed in these debates have a wide variety of historical origins. The concept of justice in the first argument has its roots in Aristotle's account of the virtues; the second argument's genealogy runs through Bismarck and Clausewitz to Machiavelli; the concept of liberation in the the third argument has shallow roots in Marx, deeper roots in Fichte. In the second debate a concept of rights which has Lockean antecedents is matched against a view of universality which is recognizably Kantian and an appeal to the moral law, which is Thomist. In the third debate an argument which owes debts to T.H. Green and to Rousseau and competes with one which has Adam Smith as a grandfather" (p. 10).