Don Boudreaux discusses the moral standing of stem-cell research in Cafe Hayek (commented also in Agoraphilia). He includes a note Steven Landsburg sent to him regarding this issue. I reproduce it here:
The embryo contains all the information necessary to create a moral agent. True. It's also true that I could, in principle, write down on a piece of paper all the information that's in the embryo, hence enough information to create a moral agent. Does it follow that the piece of paper *is* a moral agent?
Boudreaux says he agrees. I also agree with this line of argument but
I wish to clarify one point. An embryo does not contain all the information necessary to create a baby, a baby does not contain all the information to create a toddler, a toddler does not contain all the information to create an adult human, and the body of a middle-aged person does not contain all the information to create an old person.
An embryo (or a toddler or a teenager, etc.) does not contain the information about the environmental inputs necessary for development and aging. It also still lacks much of the information the body itself creates during development and that is strictly necessary for further development.
An interesting result of this is that we can write down on a piece of paper not only the genetic and non-genetic information contained in an embryo but much more of all the information that is necessary to create a moral agent. Thus we can write information about the womb and other characteristics of the mother, about the air the future baby will need to breathe or about the foods the child will need to eat.