Okay, I'm game for further intelligent conversation.
Sure, it's fruitful.. And I think "belongs to another" is a good start, but I think it also ties back to point #6 of our current argument (that defines what moral issues are). Actions which "have the potential to help or harm others or ourselves" are moral issues.
Now, objects (and by extension, property) aren't in and of themselves "others or ourselves", but I would argue that they definitely are an extension of "others or ourselves" because they belong to either ourselves or others, which directly ties back to what you are adding when you say "belongs to another". They seem to be pretty interconnected things, but in the end, it seems to ultimately be coming back to the definition of what a "moral issue" is (with the "belongs to another" bit further expounding upon what precisely constitutes "ourselves or others").
So, to get back to the example, destroying a pair of sunglasses (since property is an extension of "ourselves or others", and since potentially helping/harming "ourselves or others" is a moral issue) then destroying a pair of sunglasses would be considered a moral issue. That doesn't get into the epistemology behind it, but it does make the destruction of sunglasses (and other property) into a moral issue.
Yes, this does tie into #6, as it should if we are being consistent in this argument. Why would harming self or others be a moral issue? That's our question.
We start with a natural principle for self-preservation of life. Man's freedom raises this natural principle to a moral principle in light of the possibility of voluntary self-destruction.
Therefore, at least one objective moral principle exists -- objective in that science discovers it; moral in that Man is free to override it. The freedom to override the objective principle produces a right and a wrong choice -- right in hewing to the principle, wrong in transgressing the principle -- and thus raises the principle to the moral realm. So far so good.
But if we ask what makes self-destruction the wrong choice, what makes self-destruction immoral (and by extension harm or death to others as in #6) is that human life belongs to another, or perhaps we should say to Another. See where I'm going? I mean, it could be argued (as our friends here might if they were following our argument at all) that Man's scrupling at self-destruction is simply a hesitation in the face of the natural principle, a mere struggle with instinct. We might still argue that this struggle with instinct is a moral struggle, but like alt-oxygen (who, in contrast to the others, is following the argument) it might be argued that reason is the arbiter in this moral struggle. But Hume's Dictum haunts us here. And in order to ground the moral struggle in a concept higher than reason, I think a higher authority than reason is needed.
That's where the concept of ownership comes in. The sunglasses was just a trivial example to establish the principle. The destruction of human life, whether our own or that of others, is wrong because human life is owned by the Creator of human life.
Look, this may be overreaching, and our argument for an objective moral principle is pretty secure as it stands, but it would be grand if our argument for moral objectivity from instinct could also do double service as an argument for the existence of a Creator God.
Should we pursue this or rest on our laurels?