The other glaring problem for you is that evolution explains these things quite well. Since you were off-topic I didn't go into any detail, and I'm not going to go into a whole lot right here. Survival is enhanced by couples or groups entering into relationships based on "love" and giving and receiving such. Other animals show it, so humans are not unique in this regard, and we can obviously see how it has developed. So, unfortunately for you, we do know where it came from and your default non-answer was insufficient anyway.

A standard definition of love is unnecessary and irrelevant to the point being made. Forcing a person to risk their life and future for a hypothetical situation they are resolutely opposed to devalues their rights, privacy, freedom, and life. Eliminating one of the hypothetical scenarios can only be their own choice, even if that hypothetical option is a hypothetical new person. It's not like we're running out of people. Allowing freedom of choice is to the benefit of every person on this planet with the exception of the fetus, who has no awareness of, feelings on, or emotional investment in the situation whatsoever.

The only argument for a ban on abortion is the emotional appeal of an abstract child. Once the case becomes specific, most people realize the woman must at least be considered on par with those of the child.

If abortion is banned on the basis the fetus' safety, expect criminal charges against women who drink alcohol or coffee or smoke or do drugs while pregnant – in fact, any sexually active woman who does any of these things, because you never know when she might become pregnant. And since there's no way to identify a sexually active woman, might as well ban all those things for all women. Ideological consistency would also require an inquest for any miscarriage. Taking this to a logical extreme would lead to women being considered constantly "pre-pregnant" and expecting them to behave always in the best interest of their potential child. It sounds like some absurd Handmaiden's Tale-like dystopian future, but in fact the early stages of this process are already taking place.

First and foremost, I'd like to say while personhood is an interesting point of this debate (subjective as it is through history and cultures), it is a debate about rights, something that has yet to be addressed, along with several other points.

I think you are not thinking clearly about genetics and biology. You affirm that "genetics makes you human" - maybe, but it can't make you a human BEING, not on its own. This is the old argument about skin cells, which you yourself raised in objection to me: a skin cell is genetically "human". But it is not a human being. And that is because of biology.

I'm thinking perfectly clearly about them, you just seem to be either misunderstanding me or conflating the two. Genetics is what makes us human, and it's from this genetics that our biology (anatomy) develops. Until at least all our anatomy is in place, you can still be genetically human and not be a person, as you lack the full set of anatomy that a person has.
Of course, that brings up the interesting point that no one cell in your body can be said to be a person, merely that it can be a human cell of some nature; only when summed up can these cells equal a biological person. So if individual, differentiated cells cannot be considered people, then neither can the clumps of cells of a fetus during early developmental stages be considered a person.

I have already given an argument that responds to your problems in this area, especially when you say that it is only upon being differentiated/developed that one achieves biological identity. What kind of "biology" is that? Development is internal to the very concept of biological identity! So how can the latter result from the former?

If one does not have human anatomy, one cannot be said to be human unless through examining the genetics. If one has a full human anatomy, one can rightly be said to be a human in the biological sense of the word. This isn't complicated to understand.

Simply put development is under the control of genetics, one's biology is merely what has already developed.

Beating a chicken to death would be bad in my view, but not cracking an egg. That is because in one case I am causing suffering and distress, the other, no. But suffering is not the only thing that comes into the question when we are dealing with human life

Sure there's more to consider; like the mother's rights compounded with the fact that the fetus is not yet developed, living as a parasite in the mother's body (be it a welcome parasite when the mother wants to have a child), and the fact that the fetus will not suffer ontop of being under the medical proxy of the woman. None of which I have seen you raise as legitmate argument against.

Why would the fact that I am able to PERCEIVE the identity of something tell us anything about the identity of the thing?

It tells you how differentiated and developed it is, for starters.

(The "Biology" of something does not just mean the observable characteristics of an organism at a given stage in its development, "anatomy" as you have it, but also the relation of this given stage to all other stages. If it is a relationship of continuity and - mark ye - DEVELOPMENT, then basic biological identity can be asserted. I hope that is clear. I don't know what else I can say to make that clear.)

I read you loud and clear. Yes, different stages entail different developmental periods working on different parts of the body, in some cases growing them further or beginning their growth, and they follow predictable patterns given no errors. However, if large portions of this development hasn't yet happened, they are not part of the fetus's biology, and whether it will develop further or not is not part of the question of "how do we treat such things as they currently are". It's simply another argument of potentiallity.

Next, potentiality. You are right that the concept of potentiality cannot be rightly be said of the gametes before fusion - possibility expresses this state better. But Once they are fused, we can speak of a potentiality. But this is the point: this kind of potentiality assumes already a basic actuality, which underlies the whole movement from potentiality to actuality known as "development". So this is the same point I just made above - the point, I venture to say, that you seem to be missing.
That a minor is not (yet) an adult, and should not be treated as one does NOT mean that that it is not (now) a human being and should not be treated as one, for exactly the same reasons as above.

Potentially and possibility mean the same thing. You could say that a fetus's development begins with sperm and egg (which it does), and they form the opening stages of this "actuality known as development", or that the sperm and egg both contain that "actuality" to become one organism.
Minors are treated like humans, but humans are treated differently from each other and have different rights and considerations according to circumstance. Humans with developed brains, for instance, are treated differently from those without brains yet.

But consciousness: on what basis do you assert this? Current laws? But laws of themselves do not justify the status quo, rather, they must be subjected to scrutiny. On what basis, then?

I base it on personal opinion. Life without consciousness is, for all intents and purposes, a plant; it can never interact with you, does not have any wishes or in fact, even understanding of it's own existance. It cannot suffer and it cannot think. There is nothing definable about it, outside of the possibility of what may happen in the future and what parts of it's anatomy have already developed. However, what may develop does not mean we should treat it as if they have developed; Human life without consciousness might as well be a doll, when it achieves consciousness it becomes something more, but as always, the issue of the rights of the already living, conscious and person of a mother arch over all this debate.

We are all agreed (I think... I hope!) that "person" - whatever it refers to - refers to something that is very valuable, that is the subject of rights, that we should treat as we expect to be treated (etc). Yet, while we maintain approximately this same meaning of "person", we subtly shift the reference: now it refers, not to the "hypostasis", that which is the subject of consciousness, rights and so on, but to some subsequent determination of the hypostasis, in your case, consciousness.

Except we don't maintain the same definition of person; you maintain a different view of what defines personhood, essentially beginning from the genetic moment of conception (because let's not forget, this development you claim to be essential to biological identity is written in the genes; in case you missed that point development is regulated and controlled by genetics, biological identity is only what has already developed). Not to mention, different stages of development in people entail different rights; there are different considerations based on circumstance, again getting back to that fact that we do treat minors differently from adults, and they do have different rights, same way pregnant women have different rights when it comes to their fetus then after they give birth, then again after 18 years.

PS - in relation to your question, "do you really only have sex when you want a child?", well, I think that every sexual act has to be at least open to children. And so if people are definitely NOT prepared to have children, and (consequently) to raise them, they shouldn't have sex. This effectively means that sex should be within marriage (or at least a stable and established relationship).

How has that advice worked out in previous history anywhere it's been tried?

This is a whole other debate, it is probably a view very foreign to your way of thinking, but one that makes perfect sense if only we understand that everything about human beings (persons), including their sexuality, is ordered to committed, self-giving love, and fulfilled therein.

Except of course when they're not. I mean, it makes perfect sense if I think about people in an unrealistic way, sure.

Next, we think about chicken-embryos inside eggs differently than we do chickens, either because of what they looks like, or because we haven't sufficiently reflected on the matter, or because we're not interested about the biological aspect of the question. Beating a chicken to death would be bad in my view, but not cracking an egg. That is because in one case I am causing suffering and distress, the other, no. But suffering is not the only thing that comes into the question when we are dealing with human life. And the biological reality remains the same regardless: not with regard to development (obviously) but with regard to fundamental biological continuity and unity as an organism.
So, it doesn't matter whether I could distinguish a human fetus from an animal one or not. Why would the fact that I am able to PERCEIVE the identity of something tell us anything about the identity of the thing? It doesn't affect the fundamental biological identity at all! (The "Biology" of something does not just mean the observable characteristics of an organism at a given stage in its development, "anatomy" as you have it, but also the relation of this given stage to all other stages. If it is a relationship of continuity and - mark ye - DEVELOPMENT, then basic biological identity can be asserted. I hope that is clear. I don't know what else I can say to make that clear.)

Next, potentiality. You are right that the concept of potentiality cannot be rightly be said of the gametes before fusion - possibility expresses this state better. But Once they are fused, we can speak of a potentiality. But this is the point: this kind of potentiality assumes already a basic actuality, which underlies the whole movement from potentiality to actuality known as "development". So this is the same point I just made above - the point, I venture to say, that you seem to be missing.
That a minor is not (yet) an adult, and should not be treated as one does NOT mean that that it is not (now) a human being and should not be treated as one, for exactly the same reasons as above.

Next, criteria for personhood. Genetics and biology (not according to your definition of it, though!) I agree with (without going into possible "exceptional cases"). But consciousness: on what basis do you assert this? Current laws? But laws of themselves do not justify the status quo, rather, they must be subjected to scrutiny. On what basis, then?
It seems, because being conscious is the necessary condition for valuing one's life, from a subjective point of view. Is this necessary for the idea of person? Well, it constitutes a fundamental shift in the use of words.
As long as "person" has had a place in the tradition of Western thought, it has been conceived as the individual, the unrepeatable, and as having consistency in itself. "Persona" (although it had an interesting prehistory) was the Latin equivalent of the Greek "hypostasis", meaning that-which-lies-under, which has consistency in itself, the individual. What it refers to is not some secondary property of the being, like consciousness, but the very being itself, the person, who possesses consciousness, and rights and all the rest. Our language itself has developed with this fundamental meaning in view. We should be wary of attempts to alter it.
But when we do alter it, as we (or you, at least) have done with the term person, does that change the reality? Do things change when we decide that we want to change the rules of language? No, they obviously don't. But because things are mediated to us through language, the way we relate to things DOES change: and this is what I think is very dangerous.
We are all agreed (I think... I hope!) that "person" - whatever it refers to - refers to something that is very valuable, that is the subject of rights, that we should treat as we expect to be treated (etc). Yet, while we maintain approximately this same meaning of "person", we subtly shift the reference: now it refers, not to the "hypostasis", that which is the subject of consciousness, rights and so on, but to some subsequent determination of the hypostasis, in your case, consciousness. But does this linguistic shift mean that the hypostasis, the "person" according to the established way of speaking, ceases to actually be what it was?

These are comments intended to "make you think": they are not in themselves conclusive. Because you could reply, "It's not that the reality has changed, only that the old language was wrong in its reference. What "has value" is not the hypostasis, but the hypostasis-qua-conscious."
I tried to offer reflections in my previous post as to why that should not be the case. But actually, I think to answer this question with as much rigour as is required, we would have to delve into the history of thought, the metaphysics and philosophical anthropology of the great Scholastics, its misunderstanding, corruption and refutal by the nominalists, the modern view of subjectivity and the foundations of metaphysics initiated by Descartes (and based on a rejection of the nominalist corruption of Aquinas), its consequences for the notion of the person, which is eventually cut off from its roots in being... a discussion far too wide to realistically undertake.

Therefore, after this extensive, sometimes frustrating but always interesting discussion, I am going to have to sign off. I really can't spend any more time at this, given other commitments. And at any rate, I think we've covered quite a lot of ground. I will come back to read any reply you might give, but I will try my best to resist the temptation to write a reply (even if you still say "genetically, but not biologically"!).

PS - in relation to your question, "do you really only have sex when you want a child?", well, I think that every sexual act has to be at least open to children. And so if people are definitely NOT prepared to have children, and (consequently) to raise them, they shouldn't have sex. This effectively means that sex should be within marriage (or at least a stable and established relationship).
This is a whole other debate, it is probably a view very foreign to your way of thinking, but one that makes perfect sense if only we understand that everything about human beings (persons), including their sexuality, is ordered to committed, self-giving love, and fulfilled therein.

So if anyone doesn't want to have children, they shouldn't have sex.

That seems to grate against this point:

I also think it's worth mentioning that *all* of us almost certainly have an ancestor that was born as a result of rape or incest.

So if a woman doesn't want a child, she shouldn't have sex in your mind. However, if she's raped against her will and ends up pregnant, she has to carry and give birth to that child (then either raise it or give it up) because getting pregnant is a consequence of getting raped?

That could certainly be one of the most immoral stances I've ever heard on the matter, next to the middle-eastern philosophy of women getting killed for the crime of being raped unless she has several male witnesses.

although as I was at pains to point out at length in my previous post, it is not ONLY genetically but also biologically a human organism

Biologically, a fetus is not a person until it's finished a rather large portion of it's development. It's genetically a human being, yes, but biologically during the beginning stage it's simply a clump of undifferentiated cells. At some point during development it lacks arms, legs, internal organs, a nervous system, a functional brain, and so forth. Biologically, it's a human when it has, at least in some form of the word it's anatomy is in place and differentiated. To say it's genetically and biologically a human from the moment of conception from then on is to make the words essentially the same concept, which they aren't.

You say, "the fetus is not a person in the same way that an egg is not a chicken". I disagree with this statement. The cases are not parallel. As far as I understand it, the whole egg does not develop into a chicken, but only the embryonic chicken which is contained within the egg. The rest of the egg is food, or liquid "padding" - it is not a part of the embryonic chicken, just like the amniotic fluid and the placenta are not parts of the embryo. So if you say, the fetus-plus-placenta-plus-amniotic-fluid-etc is not a person as an egg is not a chicken, I will agree with you. But as it stands, I don't agree with you, on the basis of the biological arguments I offered in my last post.

While that is all correct regarding the composition of the egg, the point is more of one that we don't treat eggs (or the little chicken fetuses inside them) as if they are chickens until they hatch. Most people in this day and age would not be comfortable going into a field and beating two chickens to death, yet would have no problem cracking some eggs to make an omlet. The point is that we treat these two things differently, though genetically they are the same.

Option one would be to say, Whatever is a living human being is a person. This is my line.

So you have equated "genetics" (the basis for human) with "biological development" and "personhood", but even under this model were I to use it (which I don't), different people still have different legal considerations. People in vegatative states are still people under this definition, but they are unable to express their desires for care, so these calls are left up to their medical proxies, who can pull or retain life support as they feel fit/can afford. Minors are also under the medical supervision of their parents; so if these mothers feel like terminating their life-support they are still fully within their rights in the current system in both the US and most advanced cultures in this world.

I think the jury has settled it's verdict on this point.

For we can establish through biology that the fetus is a human being

Through genetics; if I gave you pictures of fetuses of different animals throughout their development, it would not be until pretty far along you would be able to accurately discriminate between which was which bases on their biology.

Now, this potentiality regards not the fact that he or she is a being whose nature involves speaking, but only the present realization of that particular capacity. In other words, potentiality in capacities PRESUPPOSES actuality in being. Otherwise, how could any of us go from not-speaking to speaking, or any other change that takes place in human development?

A fetus can potentially do a lot of things; it can potentially be born, learn to walk, speak and be a person. However, because it can potentially does not mean it has already, nor that we should treat it as if it has. If a minor has the potential to become an adult we do not treat a minor as an adult from day one, nor do we treat a minor legally as an adult. Because a baby can learn to speak does not mean it is speaking, and because a fetus has the potential to become a person does not mean that we need to treat it as a person from the moment of conception. Of course, sperm and eggs also have the potential to become humans, but we don't treat them as such either; granted they don't have a full genome, but they do have half and the potential to become human if fertilized. However, we'd both agree that the potential argument there is ludicrous, as it is elsewhere in this debate.

consciousness is always "consciousness-of"

And if the being is not, and indeed, cannot be conscious (i.e. before the brain has developed and becomes used for functions of consciousness) then it is also not a person; one way in my mind someone can lose their personhood is through loss of these functions when they enter vegatative states. This was Ebon's original point for fetus personhood; when the fetus starts to display certain brainwave patterns consistent with those of a conscious person (if I remember correctly).

Therefore, anything I am conscious of being or doing, I am conscious of it because I AM it or ARE doing it (or have been/done it). The conclusion is that consciousness cannot ground identity, but rather depends for its identity upon a previous real ("ontological" if you will) identity. This is why, in my view, we cannot coherently make personhood coincide with consciousness-of (whatever it may be, usually self). For consciousness-of-self depends on actual/biological-self.

You cannot have consciousness without the proper biology (brain at least), and you cannot have that biology without it developing from an organism's genetics. So there need to be at least three things in place to define a person:
1) Genetics
2) Developed biology
3) Consciousness

Genetics makes you human, biology gives those genetics the capacity for consciousness, and consciousness allows that biology to experience the world. Whether that all defines personhood is dependant on the situation. In the case of a fetus, that does not define personhood for me because the fetus is still within the mother, living off her body. Once the fetus is outside the mother, it retains it's personhood until it loses consciousness in a severe or permenant way (i.e. enters a vegatative state, loses functionality of consciousness, or dies). However, the rights of that person can also be altered depending on the situation (one does not have the ability to make medical decisions while in a coma, and so those rights fall to the medical proxy for instance).

But the fetus is biologically the same human being as the one who will be born and grow up (as I think we've agreed).

Genetically the same; I cannot stress that enough. Biologically, even after the fetus is born it has a lot of growing to do, though the general anatomy is in place. At the very least this anatomy is required for biological identity.

Also,

but that is the consequence of having sex, isn't it? Sex is connected to responsibility, one can't just engage in sexual activity without a thought for the consequences: and that goes for men as well. So if anyone doesn't want to have children, they shouldn't have sex. I know that sounds terribly illiberal of me. But I happen to think that the divorce of sex and moral/personal responsibility and commitment was NOT a good thing for society.

I'm sure other people will tell you this too, but sex has functions outside of getting pregnant (like feeling good, for instance), and that you might as well say AIDS and STI's are also consequences of sex, though entirely avoidable. Not to mention that pregnancy is only a consequence women have to deal with; do you think if men could get pregnant too that abortions would even be debated?

Not to mention it's completely not practical to simply try and push that line of thought; it hasn't worked for as long as it's been tried, so why keep trying and plan bound for failure, tried and tested? There are at least two types of sex I can think of off the top of my head that don't result in pregnancy, meaning there must be more to the picture than you're letting on. People are horny, people like sex, it feels good, maintains relationships, and it's a natural need of people. Do you really only have sex when you want a child, and become disappointed in every sexual act that doesn't result in conception? Do you honestly expect others to do the same?

Contraceptives work to prevent the unwanted 'consequences' of sex (same way herpies is a 'consequence' of kissing), like unwanted pregnancies and disease. I don't see how forcing people to have unwanted children (because as I've mentioned before at almost every turn, women will still get abortions, they'll just be more dangerous) they don't want or cannot afford is somehow a moral thing to promote, especially with population levels in the world being as high as they are, threatening to cause loses of lots of ecosystems, species, and ensure many people live lives perpetually mired in poverty and overcrowding.

Not only is the idea not practical, it ignores a woman's right to bodily autonomy and is dangerous to an already over-taxed environment. If you want to do the responsible thing, you should support measures that work to prevent the spread of disease and unwanted pregnancies, as well as work towards reducing population worldwide to sustainable levels through measures like child caps and free birth control distrubuted everywhere.

However, you are 100% right to say that this does not of itself force one to believe that the fetus is a person - I have said as much myself elsewhere. This is "step 2" of my argument. And even if it is a person, is the mother obliged to care for it or is she free to abort it (this is "step 3"). Therefore, it seems we have these 2 points to consider.

1) Is the fetus a person?
You say, "the fetus is not a person in the same way that an egg is not a chicken". I disagree with this statement. The cases are not parallel. As far as I understand it, the whole egg does not develop into a chicken, but only the embryonic chicken which is contained within the egg. The rest of the egg is food, or liquid "padding" - it is not a part of the embryonic chicken, just like the amniotic fluid and the placenta are not parts of the embryo. So if you say, the fetus-plus-placenta-plus-amniotic-fluid-etc is not a person as an egg is not a chicken, I will agree with you. But as it stands, I don't agree with you, on the basis of the biological arguments I offered in my last post.

But all of this still doesn't address the question, Is the embryo a PERSON? It seems to me we have two very basic options. We have already agreed, as far as I can make out, that an embryo is biologically a human being. So,
Option one would be to say, Whatever is a living human being is a person. This is my line.
Option two would be to disagree with this, and define personhood on the basis of something that a living human being does, or something that happens to a living human being. On this picture, being a person has a variable relation to being a human being: some living human beings are persons, some are not. Some were, and are no longer, some were not and now are. This is your line.

Here I cannot pretend that biology proves the case conclusively - it doesn't. The question is more "philosophical" than anything else. However, biology does give me a basis for my position. For we can establish through biology that the fetus is a human being. Now, human beings are beings that, having reached the full realization of their nature, are able to think, to be self-conscious, to make deliberative decisions, to act freely (that is, rationally) and so on. But we must note that these are all secondary activities of a being that is already existent. For a child to actually speak, he or she must already be a being who can potentially speak. Now, this potentiality regards not the fact that he or she is a being whose nature involves speaking, but only the present realization of that particular capacity. In other words, potentiality in capacities PRESUPPOSES actuality in being. Otherwise, how could any of us go from not-speaking to speaking, or any other change that takes place in human development?

So, all of the capacities that I mentioned above (thinking, deliberative decisions etc) are dependent on actually being something of a definite biological nature. Now I would ask, when I am conscious of myself, what am I conscious of? When I have an experience, what is the subject of that experience? I am conscious of myself as a biological organism; the biological organism is the subject of experiences. You see, therefore, how consciousness contains within it an indellible reference to the organism which is the subject of consciousness: as the phenomenologists rightly said, consciousness is always "consciousness-of". It needs to be grounded in biological identity and biological activity (that is, in life). Without this grounding, we are faced with an infinite regress: I am conscious of being conscious of being conscious...

Therefore, anything I am conscious of being or doing, I am conscious of it because I AM it or ARE doing it (or have been/done it). The conclusion is that consciousness cannot ground identity, but rather depends for its identity upon a previous real ("ontological" if you will) identity. This is why, in my view, we cannot coherently make personhood coincide with consciousness-of (whatever it may be, usually self). For consciousness-of-self depends on actual/biological-self.

But the fetus is biologically the same human being as the one who will be born and grow up (as I think we've agreed). ERGO, the fetus is the same actual/biological-self of which I become conscious at a certain point in my development.

I have to go now, but let me know what you think of the argument. It's not complete, but as I say, I can't write any more just now

Taking innocent human life at any stage creates a poisonous environment for everyone.

I'll repeat what I said before, according to your own theology, this argument holds no weight, because the embryo is not innocent. Besides, you might want to catch up on the whole discussion around human being vs. personhood as well as whether it is moral to bring children into this world that are not wanted and forcing women to do so in an effort to control them.

How do you know what love is? Where does a standard for authentic love come from? How do you distinguish between a loving and an unloving action?

Haven't you learned your lesson about this yet? Besides, where does your standard of love come from? The genocidal maniac you call god? Face it, love comes from our evolutionary history.

Parenthood must be a gift freely given, and the bond of family one imbued with near magical power by love. Making parenthood a burden and family a curse creates a poisonous environment for everyone

Taking innocent human life at any stage creates a poisonous environment for everyone. If we consider it acceptable to take the lives of the most vulnerable human beings, we are degrading life at all stages, whether one realizes it or not. And can you please define the word "love"? How do you know what love is? Where does a standard for authentic love come from? How do you distinguish between a loving and an unloving action?

And yes. That child doesn't deserve to die for crimes of the father.

But the woman does?