Just 'cause I couldn't resist putting my finger in this nice soup again, let's have a pick at the fundamental core problem that many people have with abortion.
Claim: Abortion is child murder.
My answer: To be murder, as in homicide, the target of abortion should be a person and alive. It is only the latter. Therefore abortion is not homicide. However, it could be defined as
feticide (which has different meanings in legal and medical contexts), which is by definition a different matter (and you shouldn't confuse the term "legal person" with the normal definition of person).
Obviously same applies to "child". Zygote isn't a child. Embryo isn't a child either. Neither of these have the prerequisites of human being in any other sense than their genome and the subsequent ability to grow and develope into a human child. They are not persons just because they might be.
You do not normally (I hope) treat people or things based on what they could potentially become. So claiming that the zygote or embryo are "children" or human beings is a flawed argument, because they quite obviously aren't. Embryo is a cluster of cells doesn't have the nervous system crucial for bringing up a personality until much later in the course of pregnancy. Abortion of the pregnancy at these stages is from biological and materialistic point of view not ending a life of human being. It is terminating a pregnancy and that's all there is to it on any reality-based argumentation that usually comes up in these arguments.
If you want to go the route that says the zygote is a human being and terminating it shouldn't be allowed, then why not declare all animal zygotes human beings? After all, they are very much identical in appearance, functions and size - heck, embryos and fetuses look, act and work very much alike in mammals (up to certain point of course)!
The argument that cow zygote or pig embryo should be considered to be human being is obviously absurd, but why? Because we know they won't become humans, but human embryo does have potential to that. However the potential is just that - it means the embryo can
become a human being, but is not human at that point.
So, I said that terminating a pregnancy is just that and that's all there is to it in biological and materialistic sense. Hormonally and emotionally it's a whole different thing obviously. Female body reacts in certain ways to pregnancy, unwanted or wanted, and it's termination usually causes some kind of adverse reactions (which is not to say pregnancy wouldn't...), either physically and mentally and usually both. So no, it isn't a matter to be taken lightly, but it MOST CERTAINLY is every female's choice up to certain point whether to do it or not.
Now, aborting a relatively developed fetus... that's a different story (as is drawing the line between embryo and a fetus). At some point, the developing organism starts to have enough nerve systems that it starts to get increasingly difficult to say it isn't killing a baby, but like I said drawing the line is very very hard. The textbook definitions say that developing human is an embryo until 8th week of pregnancy, whereafter it is named fetus, however these are just definitions of the words, obviously.
Different legislations draw the line at different point. One good point of reference could be somewhere before the fetus has the ability to (theoretically) survive a pre-term birth with intensive care. That would place the line at somewhere around... 20th week I think?
* Herra Tohtori cheks the wiki
...yeah, the youngest prematurely born child was 21/23 weeks old depending of the method of calculation. Which actually coincides with the legislations in many countries I believe.
Personally I would put the limit at somewhere closer to ten weeks for elective abortions and about twenty weeks or so for clinical abortions. Ten weeks should be ample time to find out about the pregnancy and decide whether the mother wants to carry the baby or not. After that point, there should better be some damn good reason to the abortion; best I can think of is immediate medical risk for the mother, although there are other reasons I would consider valid as well.
...Just looked it up and this actually coincides surprisingly well with the legislation in Finland:
Availability: Under certain conditions
Gestational limit: 24 weeks
Conditions: Abortions permitted up to 12 weeks to save the woman's life, to preserve her mental health, for economic or social reasons or in the cases of rape or incest.
Available up to 20 weeks if there is a risk to the physical health of woman or if she is younger than 17. The procedure can be performed up to 24 weeks if the woman's life is at risk or there is a risk of foetal malformation.
An abortion must be authorised by one or two doctors up to 12 weeks, or by the State Medical Board up to 20 weeks. Abortion is free of charge under national health insurance but women must pay hospital fees.
The International Planned Parenthood Federation (IPPF) says that in practice a woman can get an abortion on demand, but illegal abortion is rare.
TrashMan, for the aforementioned reasons comparing woman's prerogative to abortion to prerogative to "fling poo/grenades/knives at the president without consequences". Often used analogy between murder and abortion works even worse, since murder is ending a person's life.
Oh, and religious views of zygote, embryo or fetus being a human being "just because" or because it "has a soul" aren't valid argumentative material. They are non-falsifiable statements with just opinion value in this matter, like in all matters that affect other people than those with the same convictions. You can think so or believe so, but don't try to force your opinions on others after stating them.
It's not your business to decide whether those who end up with unwanted pregnancy should have the right to terminate it or not. Within reasonable time limit of course. Aborting a fetus that could possibly live a premature birth with intensive care
is actually tantamount to child murder in my personal logic circuits, but an abortion done soon enough after finding out the pregnancy... I have no problem with that at all.
Also it's meaningless to talk about developing child as "parasite" "symbiote" or any other biological terms that describe the coexistence of some species. It's called viviparous gestation and other terminology isn't quite meant for dealing with it. It's a process in a class of it's own, so to speak.
Now, placenta, there's an interesting lump of tissue, if you consider the biological structure. It basically acts as an interface between the mother and the fetus, and as such it can't be clearly defined to be belonging to either.
