Franklin Mason e-mails:
Here's a little argument for you. I seem to recall that Van Inwagen gives a little argument like this, though I don't recall where. I seem also to recall that he attributes it to Geach, too.When the zygote divides, it gives rise to a pair of new cells. Does the zygote survive its division? If it does, it is either one or the other of the pair of cells to which it gives rise. (It cannot be both, for one thing cannot become two things.) But since the two cells to which it gives rise are exactly similar, we can have no more reason to say that the zygote becomes this one than that it becomes that one. Thus neither of the pair of child cells is the proper successor to the parent zygote cell, i.e. neither is identical to the parent. Conclusion: when the zygote divides, it ceases to exist.
Note that a human zygote is in this regard precisely similar to all cells that undergo division. When an amoeba divides, it ceases to exist. When a bacterium divides, it ceases to exist. Cell division is, in all cases, at once both destructive and generative. The parent cell ceases to exist. The child cells begin to exist.
Now, assume for the sake of reductio ad absurdum that a zygote is already a human being and is not a mere precursor thereof. As argued, when the zygote divides, it ceases to exist. Thus when the zygote divides, the human being that by assumption it was ceases to exist. Of course if this were so, we must say at some point in time either at or after zygotic division, a new human being comes to exist, for of course pregnancy does end in the birth of a human being.
This is absurd. Pregnancy does not progress through the creation of one human being, its destruction, and the creation of a new. Rather there is only ever one human being within the womb. Thus the assumption with which be began must be false. It must be false that a zygote is already a human being.
Related Posts (on one page):
- 'Probative Overkill' Objections to the Potentiality Principle
- The Potentiality Argument Against Abortion and Feinberg's Logical Point About Potentiality
- Potentiality and Likelihood: Not To Be Confused
- An Elementary Confusion Regarding Dispositions and Potentialities
- From the Mail: Does Potentiality Come in Degrees?
- The Strict Potentiality Criterion of Moral Personhood
- Possibility, Potentiality, and Abortion
- Nat Hentoff: Pro-Life Jewish Atheist and Liberal
- Fetal Rights and the Death Penalty: Consistent or Inconsistent?
- The Woman's Body Argument
- Three Abortion Questions
- Smith and Brogaard on Why a Post-Birth Human Being Was not Once a Zygote
- Fission and Zygotes
- Zygotic Division: Was I Once a Zygote?
- Abortion, Speciesism, and Potentiality
- Charles Hartshorne on Abortion
- Pro-Abortion or Pro-Choice?
- Some Abortion Questions and Answers
- McCain, Obama, and Abortion
These appear to be essential reading. Thanks!
Or, one might propose a thought experiment: What if some humans twinned at age 25? Would the 25 yr. old prior to the split not be human?
Could we kill it, especially if we found out it was going to twin?
If it was human, what would the (non-question begging) relevant difference between the 25 yr old and the zygote be?
Thus there could be facts that undercut PvI's argument, or it just may be seen to be question begging, on analysis.
I dunno, what do you think?
Good comment.
Suppose Tom, a 25 yr old human being, walks into a machine that splits him into two indiscernible human twins Tom* and Tom**. Tom ceases to exist, for Tom* and Tom** are numerically distinct, which implies that Tom is not identical to either of the twins.
Can we reduce to absurdity the assumption that Tom is human? I don't see how. The Mason-PvI argument made crucial use of the premise "there is only ever one human being in the womb" as Mason formulates it. But there is no corresponding premise in your parody argument. It is absurd to say that in a normal pregnancy there is the creation of a human being, then its destruction, followed by the creation of a second human being. But it is not absurd to say that a human being twins, thereby ceasing to exist, and that then two twin human beings come to exist.
Thus the Mason argument cannot be refuted in the way you suggest.
It seems coherent to me that I could twin overnight and wake up and look at my twin, yet I still exist. I don't see why I would have to cease to exist.
But, even if not, I don't see the problem in saying that a human being was created at conception, died, and gave rise to two humans.
Since the argument is that the zygote (conceptus, etc.,) is a unified whole, a complete organism, then if no twinning occurred, you would have been in existence "as one and the same being from conception onward."
Twinning is rare. And let's leave out Hui's (and other's) view that there was always the duality. Let's say that the conceptus died but two new concepti arose. So, one person died and two came into existence. Thus you wouldn't be identical to the first conceptus since you are alive. But, you would be identical to one of the new concepti.
We'd have concepti A and B. Say you were A (your brother/sister, B). We could follow A's life as conceptus until his latest blog entry as one and the same being from conception From Maverick conceptus to Maverick Philosopher. So if X died in something like the process of asexual reproduction, we would have two concepti, and, if all went well, two people today who could trace their history to those concepti.
And, I don't understand the crucial premise: "there is only ever one human being in the womb." Not if they twinned.
And I don't understand why you say this in response to my argument:
What does the time and womb matter?
A normal pregnancy produces Tom. Tom dies at 24 hours and two new beings, Tim and Jim, come into being inside the womb. The mother gives birth to Tim and Jim (roughly) 9 months later.
What does it matter if Tom dies and splits into Tim and Jim at 24 years while inside his house (womb).
I'm a little foggy as to the cogency of the Mason-PvI argument, then.
A human mother gives birth to a single human being in the normal course of events, one neonate. So we know the outcome is a human being. Now if the zygote is a human being, and it ceases to exist when it divides, then what we have from conception to birth is first one human being and then a second human being. But this seems absurd: either there is no human being in the womb or there is one.
Franklin, where are you? This is your argument, you should be defending it!
More tomorrow.
I hope I'm not being too dense?
The split is a conception(s). So we have the conception(s) of two human beings in the womb and exist in the mother from conception to birth.
I thought you were asking about your continuity with the zygote (or conceptus)?
If you are alive today, then you didn't die yesterday.
You're alive today.
Therefore, you didn't die in the womb (back then, "yesterday").
If twinning occured, a zygote died in the womb.
Twinning occured.
A zygote died in the womb.
That zygote wasn't you (cause you're alive).
That zygote gave rise to two new zygote (cause it twinned).
Those two developed, naturally, unbroken, as a whole entity, into two people today.
One of those people is you.
Therefore, you are the same being as that zygote.
Or something roughly like that...(it's late out here)
Or, if you never twinned (thus dying), then we have an unbroken line from the original zygote to you.
So on both counts it seems we can salvage identity with the conceptus.
"Or, if you never twinned (thus NOT dying), then we have an unbroken line from the original zygote to you."
So, it seems quite coherent to say that sometimes a one-celled organism splits into two one-celled organisms, and sometimes it grows into one two-celled organism. How to tell the difference? Presumably by whether the two cells exhibit a unified life.
2. Disallowing comments from a particular person, or deleting an offensive, off-topic, or otherwise substandard comment, has nothing to do with censorship. People who think otherwise confuse censorship with lack of sponsorship. I am under an obligation not to interfere with anyone's exercise of legitimate free speech rights. But I am not under any obligation to aid and abet anyone's exercise of free speech rights, legitimate or illegitimate.
3. The Comments area is not an open forum for anyone to say anything about any topic. As the name implies, it is primarily for commenting on the author(s)' posts. But to comment on them, one must have read them. And if I have spent three hours on a post, a reader will not understand it in thirty seconds. Secondarily, the Comments area is to facilitate civil discussion between and among commenters as long as the discussion remains on-topic.
4. Some undesirables: The skimmers, those who cannot read but only read-in. The sophists who, abusing argument, argue for the sake of argument. The ideologues, those who are out for power, not truth. The uncivil. The illogical. The politically correct. Worst of all, perhaps, are those who exemplify the anti-Socratic property: those who think they know what they don't know. If Socrates was famous for his learned ignorance, these types are marked by their ignorant unlearnededness.