"Its end is the way of death," said Brownback, a Republican presidential hopeful. "It kills a young human life. It harms us as a culture when we treat human life as property. We've done that. We don't like it. We don't like the history associated with it."
A few points of interest:
1) There is no real counterargument to the fact that slaves are, indeed, individual persons with their own individual self-awareness. Not so for Embryonic Stem Cells (ESCs).
2) Slavery is a root cause of the current state of institutionalized racism. Not so for ESCs.
3) Slavery is the buying and selling of human beings as property, whereas ESC research is the use of extra cells after in vitro fertilization that are destined to be destroyed anyway. There is no buying and selling--instead, ESC research is about recycling material that was already being utilized.
4) Individual versus societal impact: Slavery gave benefits to individual owners but negative consequences to society in the form of race hatred. ESC research contributes more project ideas to individual scientists and greatly to science and the health of society.