Viability is the correct line because the 2 year old child is viable and deserves rights because it's viable fully developed but dependant. Embryos and fetus are nonviable because they need to use a viable cooperative person to create or build itself. The 2 year old is already fully created. The parents are guardians not owners of the child. People own their embryos in ivf clinics.
Wrong. A 2-year-old is not fully developed. Immune system requires special care, and the reproductive system isn't functional yet--it is still developing.
The argument you are trying to use is simply another excuse for murder. Don't come in here talking about "ownership" of embryos. Abortion stops a beating heart. Period.
The viability argument is flawed because it is based on a false premise.
A fetus is viable in the environment it was designed to be viable in at that particular stage of life, namely the womb, only by removing the fetus from its natural environment, does it cease to be viable. But that is true of every human being, and indeed all life. Put a born human being under water, and he is no longer viable, take a fish out of water, and it is not viable.
Viability is an matter of medical technology , not ethics. As our medical technology advances, the time of viability for a fetus taken out of the womb changes. The issue of when human life begins can not determined by the level of avilable technology, that would imply that a fetus that is considered a human life in modern day USA suddenly ceases to be one if the mother is suddenly dumped in the amazon jungle. What is truly not viable is a system of logic that can lead to such an absurd conclusion.