Pros
Stem cell research can potentially help treat a range of medical problems. It could lead humanity closer to better treatment and possibly cure a number of diseases:
Parkinson’s Disease
Alzheimer’s Disease
Heart Diseases, Stroke and Diabetes (Type 1)
Birth Defects
Spinal Cord Injuries
Replace or Repair Damaged Organs
Reduced Risk of Transplantation (You could possibly get a copy of your own heart in a heart-transplantation in the future
Stem cells may play a major role in cancer
Better treatment of these diseases could also give significant social benefits for individuals and economic gains for society
Cons
"We should not mess with human life."
"Humans should not be trying to play God"
Some argue that stem cell research in the far future can lead to knowledge on how to clone humans. It is hard to say whether this is true, but we have seen devastating consequences of other research-programs, even with good intentions, such as nuclear research.