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Ethical and Policy Developments 
mans, though some animal work has shown promise, and pro- 
ponents argue that they are within the reach of current tech- 
nology.'"" 
The crucial principle in all such efforts, proponents argue, 
is the preemptive nature of the intervention: undertaken at a 
stage before the transition to organismal status. They contend 
that just as we have learned that neither genes, nor cells, nor 
even whole organs define the locus of human moral standing, 
in this era of developmental biology we will come to recognize 
that cells and tissues with “partial generative potential” may 
be used for medical benefit without a violation of human life or 
dignity. Moreover, they argue, the moral distinctions essential 
to discern and define the categories of organism, embryo, and 
human being will be critical to progress in scientific research 
involving embryonic stem cells, chimeras, and laboratory stud- 
ies of fertilization and early embryogenesis. These advances in 
developmental biology, they contend, will depend on clarifying 
these categories and defining the moral boundaries in a way 
that at once defends human dignity while clearing the path for 
scientific progress.'"® 
This proposal has drawn criticism on several fronts. First, 
critics suggest, it would require significant research to assure 
that the procedure reliably produced the desired sort of “non- 
embryonic" entity yet also still yielded normal human embry- 
onic stem cells, and such research might itself be morally prob- 
lematic. Second, this proposal raises a series of further scien- 
tific and ethical questions, including those regarding the 
minimal degree of “partial generative potential” for an entity 
to be considered an organism, and for an entity to be consid- 
ered a human embryo. They point further to the risk of creating 
entities that are so ambiguous as to leave their moral standing 
in serious doubt, at least for those people who believe that the 
early stages of human life have at least some moral worth. Fi- 
nally, proposals to use human oocytes raise moral concern re- 
garding the source of supply, in this case as in the larger arena 
of in vitro fertilization and experimentation.'"® 
Although this approach has never been tested in humans, 
animal experiments suggest it has potential, and it has begun 
to play a part in the debates over the moral standing of human 
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