Well, but for me, the "making it to birth" part is important. Some animals reproduce through parthenogenesis - most people don't know that male honeybees (drones) come about through parthenogenesis. But in higher animals, it's almost uniformly a disaster, and so far, the closer one gets to humans on the old phylogenetic tree, the more and more that it appears that parthenogenesis
cannot result in viable organisms.
Now, for me, an embryo is something that at least has the potential to become a fully-fledged human being - by that standard, clones, for example, would fit the definition of "embryo", since it's entirely possible that we could develop a fully-fledged human being from a clone. But if the chances of human parthenotes developing into actual human beings are so remote as to be essentially non-existent - or just plain non-existent, period - then there's not even the theoretical potential for new life. So what purpose does it serve to call something that has basically a zero chance of ever becoming human an "embryo"?
And the second problem - with my own rendering of "potentiality", no less ;) - is that if cloning advances to the point where we can create clones from any given adult cell, then clearly any given adult cell has the "potential" to become a new life, in the same sort of theoretical way that a parthenote might be considered a new life. But does that mean that my liver cells have to be held as sacred, and rendered off-limits to medical investigation?
In my lexicon, an embryo is not a 'potential' individual human being, it IS an actual individual human being. To conceive severely handicapped individual human beings, then claim that since these are so severely deformed they will never make it to birth so let's experiment with them, is the chilling dehumanization of which I wrote in the essay. Have we come full circle now?
According to the President's Bioethics Council,
http://www.bioethics.gov/ the results of somatic cell nuclear transfer, or cloning, are "cloned human embryos." Parthenogenesis would be no different, in my opinion. The embryos develop into blastocysts, and on through development.
As to the "potential" of a being defining that being: poor logic. The embryo is genetically human and alive or it's not. Any discrimination between whether it's human enough to experiment on and kill is not scientific - it's a personal bias.