Brownback on embryos
In my view, the attribute of being a "human being" is an emergent property. That is, what makes us human is more than the accidents of genetics and biology. The fact that a group of cells has human DNA is not enough.This is a subtle point, and one that's well-made. My approach to the issue is that there is a grey area at the edge of life (its beginning and its end). It used to be that no one could see the grey area because once you hit it, you were into the clear part so fast it didn't matter. But better neonatal wards, like better life support, have allowed us to keep a body in that grey area almost indefinitely. That raises legitimately tricky questions, and these aren't questions science alone can answer.
I want to ask Senator Brownback, "How about a lock of hair, Sam? Is it a person or property?" After all, it has all the DNA needed to make a complete human being? And what about a tumor? Is my friend's cancer "sacred" human life and in need of legal protections? Any given tumor cell contains all the same DNA as an egg cell from the same person.
Of course, a human embryo is not a cancer or a lock of hair. Neither is it a human life, at least in the early stages of development. It is potentially a human life. As such, it must be treated with respect. However, its destruction is not murder.
Science can tell us when a heart starts or stops beating, or what the intensity of brain activity is, or whatever you think matters. But in the end, what you think matters is terribly important. It used to be that death was defined as a stopped heart. Then, when people were talking about the first organ transplants, they realized that the brain can be non-functional while the heart still works. And when the heart stops, all sorts of things in transplantable organs start breaking down. There was a debate, people thought it over, and no one really disputes that brain death is a valid, if not superior, way of drawing that terminal line. Science may have helped that decision along, but science cannot compel such a decision. It belongs to the ultimate class of questions, while science can only address proximate questions.
People throughout history have drawn the line for the beginning of life in different places, too. For some, the moment of birth begins life. For some, the moment of conception is the defining moment. Others have chosen the first heartbeat, the moment of implantation in the uterus, or have required the ability to live independently outside the womb. Coherent moral cases can be advanced for any of these propositions.
Speaking of tumors, what about a dermoid cyst? It's an unfertilized egg that starts dividing and differentiating on its own. It's haploid, so it is genetically distinct from the mother, and it develops hair, skin, teeth, even nerve tissue. When someone gets one, they have it removed like any other benign growth.
One can easily establish criteria that distinguish this cyst from a fetus or a fully developed child, but Brownback's definition is a little fuzzy on how one does that.