Identical Twins vs. Pro-Life

Identical twins occur when a fertilized egg splits. This can happen up to two weeks after fertilization, and can occure even later, but this generally results in conjoined twins.

This raises a problem for people who believe that human life begins at conception (i.e., fertilization). In the worst case, one can say that identical twins are a life divided, neither being a full life or as valuable as another life (and potentially eliminating the moral weight of aborting one of the twins). This is not ideal, because it is a consequence that I suspect few would accept, and those that did would certainly anger .2% of the population (not counting everyone whose circle of friends and family contains at least one identical twin).
In the best case scenario, they can say that while life begins at conception, it is able to grow afterwards. But if the life is able to grow to the extent that one morally valuable life becomes two morally valuable lives, we may thus say that the moral worth of a life is flexible, making the statement that the life has begun morally insignificant: one could consistently object “yes, the life has begun, but it has not become morally significant; it’s moral weight is at most half of what it might be.”
This seems to contradict the moral value of life beginning at conception, and thus to refute arguments that abortion should never be legal. It reveals that the moral value of life is fuzzily defined, and that such a clear line cannot be drawn at conception. Or maybe my imagination is too limited; does anyone have a defeater for this argument?

Well, I don’t have a defeater, but Sam Harris agrees with you.

He argues this same point. He also throws in the example of a chimera:

A chimera is when two separate zygotes fuse into one, forming one embryo which contains

He poses the question: how does this soul math work?

Discovering the development of human beings only changes our perceptions, not the development of human beings. For twins, they were once one being. While it may seem shocking or crazy or ludicrous, that is simply because of what our eyes see in the world. People are one being. Well, it just so happens to be that with identical twins it wasn’t that way at one time. So?

Dorky, I’d forgotten about chimeras, they’re fascinating, and definitely pose similar problems as twins.
WW, it changed things for people who hold beliefs that are hard to reconcile with this new understanding of human development. Every scientific finding is just a change in our knowledge of the world, but it can be significant because it can conflict with things we believed about the world. With this issue, it’s relatively easy to say that life begins at conception, until we consider the complications that entails. If one wants to continue to maintain that “life begins at conception”, one must explain how that can be coherent in cases like identical twins, conjoined twins, and chimeras. “Life begins at conception”, prior to considering these special issues, seems pretty straight forward: the soul (or whatever) enters the body at the moment that the male and female genetic information combines. But the explanation can’t that simple when it comes to twins, or you would have half-souled and two-souled individuals, which would skew deliberations about moral worth in undesirable ways. To continue to maintain the truth of the statement, “Life begins at conception”, would at least take some nuance, and an acceptance that abortion cannot be morally significant up to a certain point in development; even if that point is only two weeks after fertilization, it has the consequence that the morning after pill cannot be wrong. So, to answer your question, the pro-life position may be untenable, and that would have public-policy repercussions.

That depends if you believe in souls or not. I don’t. I don’t know what you mean that the morning after pill cannot be wrong…

In any case however, the stance is available that pre separation they are two souls just unknown to the eye, such as siamese twins are two souls after birth, apparent to the naked eye… + belief in souls.

There was a study done on fetuses from different mammals(not animals) including of course humans. All the fetuses were alike for the first part of gestation, during the second part of gestation was when the differences began occuring, by the last part of the second part of gestation there was distinct differences. You could tell the dolphin from the chimp and the human and you could see that the chimp was different then the human etc etc… mammal fetuses start out the same, Its when certain stem cells kick in that we become distinct creatures.
I think Xunzian can explain it all in a proper fashion.
IMO until that distinction kicks in, the fetus in a human female is just another creature that has not become human.

Maybe I should never have seen that study, :smiley:

Distinct are already present, not being able to find it doesn’t give this stance any credibility.

Not really from where I stand, if the fetus looks like any other mammalian fetus then its just a mammalian fetus. Not any different or special in anyway.

Thats subjective. Objectively it must be different.

Why? If I put two fetuses in front of you and say pick the human could you do it?

Irrelevant… baiting towards something already covered.

Its hardly irrelevent, if two fetuses are the same physically then which is the sentient human? Niether. The body identifies the sentience, not the womb.

Sentience isn’t required to be a human at the earliest of age, nor while comatose.

Comatose does not mean there is no sentience within. Unless you are brain dead and in that case the body is merely a potential organ donor.

Sentience is required to be human otherwise that fetus is nothing more than another mammal.
Sentience is what seperates us from our brethren creatures.

Animals do have sentience…

No, not animals, Mammals right now are the only creatures on this earth with the potential for sentience. The only other mammals that probably have intelligent sentience would be the whale, dolphin, porpoise or the elephant. There might be argument for seals and their cousins too.
It has been noted that omnivores have the highest potential for intelligent sentience. Carnivores and herbivores are lower.

Mammals are animals… :slight_smile: Sentience must be defined to go on, it seems you are thinking of something other than what I am.

Sentience (or sentient) is:

Main Entry:
sen·tient Listen to the pronunciation of sentient
\ˈsen(t)-sh(ē-)ənt, ˈsen-tē-ənt\
Latin sentient-, sentiens, present participle of sentire to perceive, feel

1 : responsive to or conscious of sense impressions 2 : aware 3 : finely sensitive in perception or feeling
— sen·tient·ly adverb

But not all animals are mammals. :smiley:
And thus the intelligent sentience. I granted sentience but, there is that seperation of intelligence.

I wasn’t specific to which animals… and now that the requirement is not sentience but intelligence, then 1 month olds must not be humans by that reasoning.

:laughing: Umm, no not inteligence alone, Can’t have that. Itelligent sentience is what I said.
A one month old has sentience and intelligence or rather the capabilities and potentials of both compared to another mammal. Another mammal does not have the same capabilities and potentials. A pup does not have the same capabilities and potentials as that infant does it? No.