[Irouléguy] Not circular, but certainly flawed. We don't need, and nor can we infer the existence of, a universal rule-set, however we do need a rule-set which covers at least the special case(s) covered by the proposition we know to be true in order to test it, as you say, but we can say (and this is what I was getting at) that if the proposition is true, then such a special-case rule-set must exist, even if its only rule is the true proposition itself. Bringing in the special-case rule-sets, a proof that there is no universal rule-set doesn't discount the possibility of a special-case one which covers only finitely many possibilities, and therefore it is possible for a proposition to be demonstratively true or false even if there is no universal rule-set.
(Er... by that I mean the focus of what I'm talking about has shifted away from morality into how logical propositions [can] be members of larger sets of rules mapping one class of items to another.)
[Irouléguy] The moral organising to remove unjust rulers happens now and then, for example, in Iraq. (I am not joking.) Imposing the rule of the moral, though, is a contradiction in terms. Rule can only be imposed on an unwilling populace by killing enough of them to intimidate the rest. What is moral about that? Re your second point, you see it or you don't. That is the key difference between empirical knowledge and moral knowledge: one is demonstrable and the other is not. On your third point, why didn't the just man thump the unjust when he tried to make off with his umbrella? Sometimes crime pays and sometimes it doesn't.
[Projoy] Indeed, mugging someone cannot be demonstrated to have those negative effects upon the soul that have nothing to do with the courts. The world-view I'm arguing is one that can only be held as a matter of faith. That, it occurs to me, is what religious faith really is. It is not belief in stories about empty tombs or dictating angels; it is the belief that not only are good and evil knowable, but the knowledge is closer than your own heartbeat. But to return specifically to mugging, muggers are not notably well-off, materially successful people, are they, even if they never go to jail? There are no rich muggers.
The supposed negative consequences of sin are not some sort of consolation for the good -- "he stole my wallet, but he'll burn in hell for all eternity, so that's ok". Morality only has application to oneself. Other people will do whatever they do, whatever one thinks about what they do.