When Stanford University researchers refused to use the words "cloning" and "embryo" in announcing their new stem cell institute in December, the chairman of the President's Council on Bioethics, Leon Kass, accused them of obfuscating the debate about embryo research. Kass's accusation is fair. But it's too bad that the council wasn't equally outspoken a few months ago when the Bush administration did its own bit to obfuscate the debate about embryo research and asserted that embryos enjoy the same protections as human subjects. Obfuscation by both sides makes it difficult to have a much-needed public conversation about the difference between acceptable and unacceptable forms of embryo research.

It's already hard enough for most of us to keep straight basic facts about research involving cloning and embryos. Along with followers of the cult leader Rael, trained reproductive specialists such as Panos Zavos and Severino Antinori claim to be working at producing cloned babies. That is, they say they are creating babies by what's technically called somatic cell nuclear transfer, or SCNT. By transferring the nucleus of an adult, or "somatic," cell to an egg that has had its nucleus removed, researchers produce a one-cell embryo. At least in theory, such embryos are grown in petri dishes and then transferred to women's uteruses, ultimately becoming children.

At almost the same moment the Raelians launched their publicity campaign claiming they were about to unveil the world's first baby produced by SCNT, the Stanford researchers announced they were opening a center that also will use SCNT. The Stanford researchers, however, have no intention of producing babies. They want to produce six-day-old embryos in petri dishes, from which they will harvest embryonic stem cells, which they hope to turn into lifesaving cures. Because the Stanford researchers don't want public concern about cloned babies to derail their research, they understandably don't want to use the C-word. Their refusal to do so was what moved Leon Kass to level the obfuscation charge.

The complex range of things we can do with embryos cries out for clear thinking. Indeed, embryonic stem cell research isn't the only line of embryo research that could reduce human suffering by creating new medical treatments. And reproductive cloning isn't the only line of embryo research that could inadvertently create new forms of suffering.

Again, the Bush administration revised the charter of a federal advisory committee to specify that "embryos" would now be considered -- and enjoy the same protections as -- "human subjects." In a country that has been debating the ethics of using six-day-old embryos in petri dishes to produce medical cures, this is surely just as much obfuscation as refusing to use the word "clone."

Kass is right. The folks at Stanford should acknowledge that they're using SCNT to create embryos. That might move some people to think we're on a slope we should get off right away. My guess, however, is it would cause more people to think it's time to start articulating the difference between those purposes of embryo research that they oppose and the ones they endorse. It would be nice if we could afford to rule out entire lines of research because we don't like one purpose to which they could be put, but that approach probably won't fly with most Americans.

The folks in the Bush administration, meanwhile, shouldn't use language implying that six-day-old embryos in petri dishes are human subjects. Whatever they are, they don't fit neatly into either the category of human subject or of mere property. It would be nice if it were otherwise; that would make public conversation and ethical decision-making easier. But it's not that simple.

Surely the Stanford researchers and the Bush officials agree that we need a public conversation about the uses and abuses of embryo research. Remembering that might help both sides refrain from obfuscation that makes such a conversation impossible.

The writer is a senior research scholar at the Hastings Center, a bioethics research institute in Garrison, N.Y.