>> ^imstellar28:
So lets leave the discussion to focus on homosapiens for the time being okay?

No, because your humans -> sentient -> humans argument contradicts you assertion that the criteria for who may/not be considered to have rights must not be arbitrary.

That said, "murder by negligence" is a contradiction in terms.

So letting go of the rope in the fruit picking example (sans language) is not murder. If that's the consequence of your position, I declare your position absurd.

... it would be easier to see why your premise is incorrect.

If the world were not as it is, then my position may be incorrect, to assert that it would be clearly incorrect under non existent circumstances does not help your point, we are not talking about "if the world were like this" we are talking about what makes sense based on how the world is.

It appears to me that you are making an "objectivist" argument that everything is contract, I will ignore the fundamental absurdity of that for a minute, and apply it to the issue at hand.

Contracts, as the tree/rope example illustrates, are agreements based on expressed intent, of which language is only a special case of an action which expresses an intent. A zygote implanting in a womb wall also, through action, expresses intent, more clearly I would argue, then intent can be expressed in language. Deciding to not withdraw support for this zygote over a few months also expresses intent, if even just acceptance, of the clear objective of the zygote. Through a period of sustained cooperation the mother enters a contract of implied support, just as the rope holder does, even if he never says "I'll keep holding the rope until you get down". Without this kind of implied contract (sort of a base case social contract) none of the basic human cooperation that any society requires are possible.

>> ^imstellar28:
I would agree, if it were possible to prove the mother and fetus voluntarily entered into a contractual agreement.

Reconsider my fruit picking example, assume that we share no language in common, how do you "prove" the contract in this case? If you can't, am I morally free to let go of the rope?

Mules are sterile, which is why horses and donkeys are considered different species.

You just moved the goal posts. You said reproduction, donkey -> mule -> horse is a reproductive connection, now you say sterile does not count, so sterile offspring of humans are a different species? Also consider that not all mules are sterile, so where do the offspring of mules (which are often genetically indistinguishable from horses) fit in your equation?

Given that morality requires a conscious choice, it would appear that only sentient beings have rights?

And there my friend is the rub, who decides who is "sentient", and what are the criteria? Do we exclude members of a generally sentient species who are not themselves sentient? None of us are functionally sentient while asleep, or in a coma, do we abandon our rights when we go to bed and regain them in the morning?