Either an embryo is a human life—or it isn't. There is no middle ground. Either you and I were each once entirely contained within an embryo—or we weren't. If we were, then taking apart an embryo is morally the same as taking apart you or me.I agree with the first and second sentence, but after this things go south. I think this is because "entirely contained" is a heck of a simplification.
An embryo is a potential person however it does not "entirely contain" all that we are. After all an embryo is a small group of cells. It weighs next to nothing. How does that entirely contain what might be an eight pound child in nine months? The Law of Conservation of Mass says that it can't. In order to make the mass balance out you have to consider the nutrition supplied to that embryo by the mother. The mother is a non-negligible part of that equation and the system of fetal development.
So is the embryo negligible too? Just a cluster of cells? Of course not. There are those that would say an embryo is "just" some genetic material like say the tip of your finger or the "tag" at the end of hair. The "just" gives away which side of the debate these people are on. Unlike your finger or a hair, the embryo is a unique genetic whole unlike anyone else on earth. It is special in its own way, different from all others, and sacred.
Traditional Jewish logic on this subject has been growing on me. Jews traditionally believe that unborn children are potential life. They are created by God, however they are not accorded the rights of a full-fledged individual because they are physically dependent on their mothers. This is why Jews do not traditionally oppose all abortion on principle and may require it if the mother's life is in jeopardy. This seems about right to me.
This does not mean I support the current changes to stem cell law. I don't. I think the president's plan is generally a good compromise and that, in the end, it is adult stem cells which will have to be used for supply reasons. The alternative for embryos is pretty gruesome.
What it means is that I do not like the oversimplified rhetoric of the right to life movement, which is different. Having given financially to several conservative causes, I am aware that fund raising among many political groups basicly encompasses trotting out strawmen in order literally scare up more money from the membership. I don't like that one bit.