There is a connection between inconsistencies of existential import and contradictions of beliefs. The connection is that all of us, in one way or another, live according to what we think is true. If we say we believe one thing (as in my examples) and yet carry on our lives as if we didn't, that surfaces a contradiction between our beliefs on one level and our beliefs on another.In answer to my comments defending relative morality he writes:
As regards ethics being a matter of taste, or "we just feel," that's ground we covered before, so as I wrote in my first comment, I don't see a need to go there again. I think it's an outrageous opinion that leads in all kinds of both goofy and dangerous directions, since (for just one example) it opens the door wide to tyrants doing what they feel like, with no good answer to them.The problem with this appeal is that it hides meta-rule of morality.
The lack of an absolute morality does not imply that I have no good answer to tyrants. Relative morality does not automatically include the rule that one ought never interfere in the relative moral decisions of others. If there were such a rule, it would indeed be wrong in my own morality to complain about acts committed against me under someone else's morality. Fortunately, there is no such rule.
Does the lack of such a rule commit us to unending moral war against one another?
Cold war, perhaps.
Rules governing moral interference are part of social contract - a treaty that enables people to compromise and live together despite differences in relative morality.
Thus is deflected the thrust of the original argument that moral relativists are living life inconsistently. Not that the inconsistency invalidated the original claim, but it wouldn't have looked good.
I think that, in the end, every moral argument is a question of persuasion, not proof. Yet, the moral absolutists appear uncomfortable with this state of affairs. They appear to be re-casting moral arguments as proofs by embedding the persuasive elements into some form of absolute morality. From there, they can deduce that X or Y is wrong (tautologically), instead of directly persuading us that X or Y is wrong. However, this is just a facade. They have shifted the object of the persuasion from the practice of X and Y to their absolute morality. They then proceed to try and persuade us to accept their absolute morality by providing us with case studies and thought experiments that we might find subjectively persuasive.
Existential concerns are definitely vital in any moral debate. They are the aforementioned persuasive elements. However, I think that building a purportedly-absolute deductive framework on top of those existential effects only confuses the issue. Anyone who explores the framework in detail can see that it is no more persuasive that the existential effects that justify it, while the framework is sold to the average Joe as a fact of nature.