Steve Mirsky in Scientific American:
Here’s another idea that’s really been vexing me. Human embryonic stem cells are bad, I’ve been told, because they come from aborted embryos or from surplus embryos created for in vitro fertilization. And using these cells in potentially lifesaving research is morally wrong because even if that embryo was only a few cells or just one cell, it has the potential to be a human being. To some people’s thinking, it already is a human being. On the other completely gestated hand, what are called induced pluripotent stem cells (iPSCs) are allegedly good because no embryos are involved. An iPSC is a tissue-specific adult cell that, with special treatment, has reverted to a fully pluripotent form capable of producing any other kind of cell in the body. In fact, it’s theoretically capable of being implanted into a welcoming womb and developing into a human being. Oh, the result would be a clone and therefore pure evil, but it would definitely be a human. So what I don’t get is why aren’t people who are against using embryonic stem cells in research just as against using iPSCs? Is it because of the evil clone thing?
By the way, freezers in fertility clinics all over the country are filled with those surplus embryos, which some consider to be human beings with all the rights and privileges thereof. And there’s a thought experiment in which a fully developed human baby-type person (that detailed description is meant to ward off semantic issues about who’s a human or what’s a baby) is in the clinic sitting on one of those freezers when a fire breaks out—whom do you save, the crying baby or as many of the frozen embryos as you can? (Hint: if you leave the baby, you don’t get invited to the spaghetti dinner at the thought-experiment firehouse.)
More here.