I believe that many fundamental ethical and moral stances can be deduced rationally because many of these ethical stances are based more on reason than culture.

This does not mean that there is only "one interpretation". This means that many interpretations will come to the same conclusions in their own unique ways. Why? Because ethics and morals are formed not within a culturally distinct bubble, but in a world governed by intrinsic natural laws. Cause, effect, and consequence (the fundamental building blocks of ethical understanding) are inherent to the nature of the universe and the process in which events unfold through these states are predictable and understandable. To put it simply: sociology, anthropology, and philosophy are all sciences (and by that very nature, are merely chronicling and describing the logical structure and mechanations of the universe).

I also don't understand your use of the term "grammar" here. I actually teach grammar, linguistics, and English literature and I still don't know what you mean here. Perhaps you mean "definition"? We seem to be discussing semantics, not syntax.

there's nothing wrong with causing the deaths of the civilians who live in and amongst military personnel

According to the 193 nations of the UN (and thus, the vast majority of the world) there very much is something wrong with this.

For someone who accuses me of egocentrism, I find it strange that you're making such cavalier assertions that quite confidently toss aside all current military law and the conclusions of many men and women far more educated and far more versed in issues of ethics and morality than you or I to so assuredly assert "There's nothing wrong with murder here".

And I think you're misunderstanding much of what I'm saying. I'm not saying "You murdered an innocent child, and that makes you a bad person" or that the actions that led to the murder of an innocent child were without motive or were unnecessary. The Bajorans' actions led to the freeing of Bajor and quite possibly saved countless Bajoran lives.

This does not, however, erase the murders of the innocent. Nor do they make the murdering of innocent lives less of a reprehensible murder.

Ethics is not math. You do not simply add right things to wrong things and get an even net sum. Kira took innocent lives. There's nothing that comes before or after those events that makes that statement any less true.