Destroy an arm or leg, and the human being still exists. Destroy the nervous system, and the human being is gone--even if the rest of the body can function on a respirator for a time.
Or, to put it another way, any organ can be transplanted into a person, and that person will remain the same fundamental person he/she always has been. But if a brain transplant were to take place, the essence of the person would be the person from which the brain came, not the body into which the brain was transplanted.
A cell may be human, but if it is not a cell which, if not deliberately destroyed, would grow into a baby, it is not a human being
*Any* human cell has the ability to grow into an embryo, given the right set of chemical signals. The chemical signals that drive the development of an embryo aren't even present in all products of conception. Only about 10-15% of fertilizations survive until birth (in the absence of abortion).
This is why I dislike philosophical measures of when it is or is not okay to kill. You can choose any arbitrary point if you avoid objective science, and then the pro-abort/pro-life debate devolves into an argument over which arbitrary point is superior. OTOH, the presence of awareness is something that can be objectively determined based on the status of development.
——even if the rest of the body can function on a respirator for a time.-——
Heresy........ antiTerry statement
Gratuitous assertion. Question-begging.