That's extreme pedantry, a worthless and annoying thing, especially the part about the definition of murder. Of course I meant immoral killing when discussing the topic universal morality, and that doesn't need to be pointed out to anyone who reads it in context. Murder is a succinct word whose meaning here would be understood by most everyone and by anyone who takes a moment to consider it in context.

And it's not even right. It is absolutely a cultural human universal in the descriptive sense that it is immoral to kill members of the in-group without a strong justification (which is why an execution is neither murder nor generally considered an immoral killing by its practitioners), and that has been the case in every human culture. I would even say the part about the 'in-group' is overly limited and imprecise because it's not so much that killing anyone a part of your social or cultural grouping is evil, but that killing anyone endowed with a basic 'humanness' is evil as even in many ancient and violent cultures there was an extension of this protection from killing to foreign travelers who were decidedly not a part of the in-group but still recognized as not being acceptable targets of violence just because of that. This is descriptive. It only becomes normative once you get into the specifics of who is human (and some cultures extend this norm even beyond humans) and what constitutes justifiable killing. This is not banal logic either, it is one of the fundamental facts of human social, cultural, and perhaps even neurobiological traits that has persisted in every environment and time period. It's not even a matter of logic, it's demonstrable fact.