As a note, the morning after pill is -technically- not an abortifacient by the truest sense of the word, as their primary method of efficacy is prevention of ovulation. While there is some evidence that their action may also prevent implantation (so a fertilized embryo wouldnt attach...to each their own if that is considered 'abortion') the same can be said for a copper IUD, which is absolutely considered to be a contraceptive, NOT an abortifacient.
So that being said, that is why I stated earlier that separation of the various causes of unwanted pregnancy is important, and why (strings' points regarding the fact not all raped women seek medical attention in a short enough time period) if plan B is considered to be not an abortifacient, then my point remains that in the day and age, actual abortions should not be necessary except in the "life of the mother" case.
In my opinion, a fertilized, unimplanted embryo is not an independent life. My logic being:
1. since ALL embryos have the potential to become twins, in the case of identical twins vs single fetuses, the differentiation from one independent entity to multiple occurs post implantation and post cell division, the "identity" of the entity cannot be established until that occurs.
2. It is no more an independent life than a unfertilized egg or sperm cell--both of which are alive, but cannot live independently (they have no method of imbibing nutrients or oxygen other than in the uterine lining in the case of an egg or at all in the case of a sperm. Additionally, while a fertilized egg has a different genome than either parent, so does each parent's reproductive cells due to crossover and other meiotic actions. Additionally, it has been shown in vertebrate eggs that the necessary chromosomal doubling can occur without a second reproductive cell (ie cloning), so again, an fertilized unimplanted egg has no more potentiation than an unfertilized unreleased egg in a follicle.
3. A pluripotent stem cell can technically create a whole new cloned human being, as it has the same genetic potential as the fertilized egg that created the individual. While these stem cells are referred to commonly as "embryonic" stem cells as they are most commonly obtained from multicellular embryos before any differentiation can occur--breaking apart the embryo at this stage is identical to the process which creates identical multiple births, it has been determined that pluripotent stem cells may exist in an post birth human, in which case, as these cells have the same technical potentiation as a fertilized unimplanted embryo, does that mean that if one of these cells were say, on some skin tissue that you scratched, does that mean you "aborted" that potential life-form?
4. While fertilization results in cellular changes that enable the now fertilized egg to begin dividing (mitosis), it is one step in a process of cellular changes that take a egg in a follicle (which doesn't divide, ever) to a dividing embryo. These changes, plus the addition of the other chromosomes are required to result in a new genetically different, embryo undergoing growth through cell division. However, as meiosis failures (triple chromosomes, missing chromosomes) can occur, (or nuclear replacement with a full set of chromosomes) it is technically possible that the process by which the egg starts dividing can occur artificially and without "fertilization" (the combining of the two groups of chromosomes) can occur (we have to define fertilization this way, as it is technically possible for a sperm and egg to combine with no transfer of genetic material and this a non-viable embryo).
Given that, that it has undetermined identity of potentiation and no more of a different genome than an individual egg or sperm, it is logical to come to the conclusion that "life" (an independent entity with determined potentiation) begins on implantation and the first few cell divisions (once the embryo rewches the point where it has differentiated sufficiently to fix its potentiation into a single life form) otherwise, since all fertilized unimplanted, or implanted but Pre-division cells can potentially be twins, any single pregnancy is technically the elimination of at least one potential independent life (the twin that never occurred). Additionally, due to variety of steps and exceptions stated above, the embryo cannot be considered "living" in the same sense as an independent life form until implantation and division, as until those occur, it cannot eat, excrete, have a fixed identity, or grow or reproduce--the aspects that are fundamental to "life". Before implantation and division to diversification, it is a cell or group of cells that cannot exist for other than a short period of time, has no more genetic diversity or identity than potential cast off tissue cells or reproductive cells, and has an upon determined potentiation (like stem cells), so it should be reasonable to conclude that before this point it is no more an independent life than the other examples.
Now, I am expressing an opinion here, not about the right or wrong of abortion, but rather how to better (ie using logical argument based on scientific facts) define "life beginning"--the argument can be made that while parasitic, a new, fixed potentiation identity is formed at the post implantation and division to diversification point, not fertilization.
Anyway...just trying to add some thoughts to the debate.
