This is where the discussion is relevant, if it's a human killing it is murder. Your later argument seem based on a unborn human as being less human than one that has been born. I think this idea could be defended but you should defend it before contradicting the consensus of the thread.
I don't believe it is murder to kill a human, simply because it is human. If we really adhered to that vague, unqualified premise, then it would lead to many absurd consequences, and I don't think you want to bite that bullet. I wille explain about this later in part B and C.
A. I think you misunderstand my argument. I
do not believe an unborn human
is any less human that an adult or one who is born. I specifically mentioned that it's silly to discuss which one isn't and is human, since they are, by virtue of being part of the human species, human. There is no debate. Furthermore, I think it's pointless, because, as I will indicate in part C, being human itself is not an adequate criterion for moral worth or whether or not it's right to kill something.
If we use the unqualified premise: "It is wrong to kill humans because they are human," we fall into the following problem:
Let's kill Bob:
1. No, it is wrong to kill humans
2. Why?
3. Because they are human!
4. Why is their human membership important?
5. Because they are human and it's wrong to kill them!
Clearly, this leads nowhere, as the individual cannot muster up a criterion or aspect about humanity that actually makes it wrong to kill him. They simply repeat ad nauseum that it's wrong "just because." This is the equivalent of "nuh-uh!, Ya-huh!"
The premise fails because it is too vague, unqualifie, and really...it doesn't explain a reason why it is wrong to kill humans. It just assumes it. One could equally claim it's wrong to kick rocks because they are rocks: after all, the only criterion is it being what it is, nothing about it's actual characteristics.
Imagine a rubric for a project that doesn't say anything about what the criteria mean. You just get a grade, and you ask why something you wrote was wrong, the teacher saying: "because it's wrong!" but unable to answer why. Likewise, to claim that it's wrong to kill humans, but lack any criteria for why, save species membership, is a circular non-explanation for why it's wrong. It's virtually identical to someone saying: "it's wrong to kill trees because they are trees." It ceases to be a good comparision when one uses genuine moral criteria to distinguish between the two: cognition and self-awareness. This leads to the concept of moral personhood, which is really what is important, and it's different from being human.
B. The premise that it's wrong to kill humans, simply because they are human, would logically entail a position that euthanasia is wrong, simply because you might be killing a human Why? Because the only criterion given for why it's wrong to kill a fetus is that...it's human. There is no mention of any cognitive faculties. It would also mean it's inherently wrong to kill anacephalic infants, simply because they are human, despite the fact that they are unthinking parasitic blobs with no brain...yet they are fully human and members of the species. Clearly, it's "murder" to kill them under the aforementioned premise. it's also "murder" to kill an embryo who has no self-awareness at all, cannot think (because he has no functional brain). It's also "murder" to kill a vegetable whose brain is melted mush, only kept on life-support forever until her body collapses (Terry Schivo). Clearly, this is a ridiculous premise. It's not the human-memembership that makes it wrong to kill. It's utility and the degree of personhood.
Clearly, a vegetable, an embryo, and an anacephalic infant are not equal to normal humans. They have something the former do not have. What is it? Higher Thought. Cognition. Selfhood. The abiltiy to create desires, preferences, wants. They see themselves as existing. As I explained, moral personhood is the sense of self, of higher level cognition and thought, and the wetware abiltiy to see oneself as existing and have the capacity for future oriented preferences, desires, wants. It is wrong to kill a person, because that person will have desires, wants, preferences thwarted. If it can see itself existing, it knows it has something to lose. This is different from killing a bacterium which doesn't know it's alive either way, cannot desire to continue living, and cannot think about anything. The person, contrarily, has a life to live with desires projected. It can think, suffer. Neither a bacterium nor a rock can do any of that, nor can any animal to our degree, which makes it, in general, more wrong to hurt or kill humans. However, nothing is absolute, as morality stems from utility (euthanasia, e.g.)
A Human may not be a person, because he may lack the requisite cognitive faculties threshold for minimum personhood: higher level thought and brain activity. A dead man is a human. But what he is lacking is personhood. So is a vegetable. When your brain dies, so dies YOU as a person. You may be kept mariginally alive on your brainstem almost indefinitly until your body collapses. But this is not what it means to be a person. A vegetable is not a person. Hopefully you can see the moral difference and that it's hardly murder to kill these things because they are "simply human." It is not until later in pregnancy that the fetus gains minimal personhood by attaining functionality of the higher brain and can actually "think."
Medically, it makes sense to determine the bare minimum at higher brain activation, since person-death coincides with disintigration of the higher brain functions.
My method is superior for answering why the death penaltiy could or couldn't be wrong. It has nothing to do with whether the being is simply human. While as a rule of thumb, it is more wrong to kill an adult than a fetus, with the former having very little worth in the early phase, it doesn't mean that any being has absolute worth. Such doesn't exist. Whether or not it's wrong to kill also depends on the utility of doing so insofar as it prevents equal suffering or harm to society. It's not "murder" to kill an inmate in a prison, which would logically follow given the premise that killing humans is murder because they are human. Clearly, many people do not believe that it's wrong to kill criminals, which, if we assume is a valid point, denies the concept that it is inherently wrong to kill humans (and thus is considered murder) simply because they are human. There is a utilitarian calculation at work that negates the human worth, even if the rule of thumb is that they have worth. Their worth is negated by the harm they pose to others and the possible deterrant effect. (Although I don't support the DP).