Introduction 
7 
ies are conducted will we discover the potential therapeutic 
value of stem cells from any source. How, then, in the mean- 
time should we discuss these matters, offering encouragement 
but without misleading or exploiting the fears and hopes of the 
desperately ill? 
Finally, questions are raised by some about the social sig- 
nificance of accepting the use of nascent human life as a re- 
source for scientific investigation and the search for cures. 
Such questions have been raised even by people who do not 
regard an early human embryo as fully “one of us,” and who 
are concerned not so much about the fate of individual em- 
bryos as they are about the character and sensibilities of a so- 
ciety that comes to normalize such practices.^ What would our 
society be like if it comes to treat as acceptable or normal the 
exploitation of what hitherto were regarded as the seeds of the 
next generation? Conversely, exactly analogous questions are 
raised by some about the social significance of refusing to use 
these 150-to-200-cell early human embryos as a resource for 
responsible scientific investigation and the search for cures. 
What would a society be like if it refused, for moral scruples 
about (merely) nascent life, to encourage every thoughtful and 
scientifically sound effort to heal disease and relieve the suffer- 
ing of fully developed human beings among us?® 
It is against the background of such moral-political discus- 
sion and argument that the Coimcil has taken up its work of 
monitoring recent developments in stem cell research. We are 
duly impressed with the difficulty of the subject and the high 
stakes involved. All the more reason to enable the debate to 
proceed on the basis of the best knowledge available, both 
about science and medicine and about ethics, law, and policy. 
Before proceeding to the results of our monitoring, we com- 
plete this introduction with some additional comments on the 
different types of stem cells, a few terminological observations 
and clarifications, and an overview of the report as a whole. 
m. TYPES OF STEM CELLS: AN INTRODUCTION 
Although we shall report later (in Chapter 4) on recent de- 
velopments in basic and clinical research using various types 
PRE -PUBLICATION VERSION 
