{"id":7846,"date":"2014-07-10T13:10:11","date_gmt":"2014-07-10T13:10:11","guid":{"rendered":"https:\/\/maverickphilosopher.blog\/index.php\/2014\/07\/10\/zygotic-division-was-i-once-a-zygote\/"},"modified":"2014-07-10T13:10:11","modified_gmt":"2014-07-10T13:10:11","slug":"zygotic-division-was-i-once-a-zygote","status":"publish","type":"post","link":"https:\/\/maverickphilosopher.blog\/index.php\/2014\/07\/10\/zygotic-division-was-i-once-a-zygote\/","title":{"rendered":"Zygotic Division: Was I Once a Zygote?"},"content":{"rendered":"

Here is yet another entry from the now-defunct Powerblogs site.  It is pretty good, I think, and deserves to be kept online.<\/span><\/p>\n

………….<\/span><\/p>\n

Have I been in existence as one and the same human individual from conception on?  Of course, I and any intra-uterine predecessors I may have had have been genetically human from conception on: at no time was there anything genetically lupine or bovine or canine or feline in my mother's womb. The question is whether I am numerically the same human individual as the individual that came into existence at 'my' conception.<\/span><\/p>\n

\n

The following argument seems to show that no zygote is a human being and that I have not been in existence as one and the same human individual from conception on.  The argument is a variant of a much more complicated argument presented by Peter van Inwagen in Material Beings<\/em>, Cornell UP, 1990, p. 152 ff. (In note 55, van Inwagen cites Peter Geach, The Virtues<\/em>, Cambridge UP, 1977, p. 30.)<\/span><\/p>\n

The argument is essentially this:<\/span><\/p>\n

1. A zygote is already a human being. (assumption for reductio<\/em>)<\/span>
2. When a zygote divides, it ceases to exist. (premise)<\/span>
Therefore<\/span>
3. When a zygote divides, the human being it is ceases to exist. (from 1, 2)<\/span>
4. At or after a zygotic division that terminates a human being, a new human being comes to exist. (premise)<\/span>
Therefore<\/span>
5. Pregnancy involves the creation of two human beings. (from 1, 4)<\/span>
6. (5) is absurd: there is only ever one human being in the womb.<\/span>
Therefore<\/span>
7. (1) is false: A zygote is not a human being.<\/span><\/p>\n

Since the inferences are valid, the soundness of the argument rides on the truth of its premises. I will not question the truth of (4). The normal outcome of (a human) pregnancy is the birth of a human being. Premise (2), however, seems open to doubt.<\/span><\/p>\n

First we need to understand the reaoning behind (2).  If Z splits into A and B, there appear to be three possibilities: Z continues to exist as A; Z continues to exist as B; Z ceases to exist.  But any reason one gives why Z continues to exist as A is equally good as a reason why Z continues to exist as B. Since Z cannot continue to exist as two things, both of the first two possibilities are ruled out.  This leaves the third: Z ceases to exist.<\/span><\/p>\n

There is however a fourth possibility:  when a zygote divides, it does not cease to exist, but changes from a one-celled to a two-celled organism.  Of course, one thing cannot become two things. But a one-celled organism that becomes a two-celled organism is arguably one and the same organism which exists at two different times. One thing does not become two things; a one-celled thing becomes a two-celled thing.<\/span><\/p>\n

Zygote Z becomes embryo AB. Must we say that Z ceases to exist and AB begins to exist? Why can't we say that the organism that is Z continues to exist as AB? Crude analogy: I have a burning log L in my fireplace. L breaks into two burning pieces P1 and P2. Does L cease to exist to be replaced by P1 and P2? One could say that, but it seems equally reasonable to say that L continues to exist composed of two distinct parts P1 and P2.<\/span><\/p>\n

Van Inwagen rules out the possibility I am suggesting:<\/span><\/p>\n

It does not follow, therefore, from the fact that the zygote is an organism, and hence a real object, that the two-cell embryo that replaces it is a real object. Why should we believe that there something that B and C compose? They adhere to each other, but we have seen that there is no reason to suppose that two objects compose anything. (Material Beings<\/em>, p. 153)<\/span><\/p><\/blockquote>\n

I don't understand why van Inwagen says that "there is no reason to suppose that two objects compose anything." I find bizarre his denial that there are such things as ships and houses, and the implication above that an embryo, though composed of living things, is not itself a living thing.<\/span><\/p>\n

Was I once a zygote? Yes, as far as I can see, van Inwagen's argument notwithstanding.<\/span><\/p>\n

One thing is very clear: metaphysics is unavoidable.  Just a little thought about a 'hot button' issue such as abortion lands you right in it.<\/span><\/p>\n

See Van Inwagen on the Ship of Theseus<\/a> and Puzzling Over van Inwagen's Denial of Artifacts<\/a><\/span><\/p>\n<\/div>\n

\nRelated articles<\/legend>\n
\n
\"\"<\/a>Van Inwagen on the Univocity of 'Exists'<\/a><\/div>\n
\"\"<\/a>A Second Van Inwagen Argument for the Univocity of 'Exists'<\/a><\/div>\n
\"\"<\/a>Still Trying to Understand Van Inwagen's Half-Way Fregeanism about Existence<\/a><\/div>\n
\"\"<\/a>'Something is Self-Identical' Cannot Translate 'There are Objects': Another Argument Against the Thin Theory<\/a><\/div>\n<\/div>\n<\/fieldset>\n","protected":false},"excerpt":{"rendered":"

Here is yet another entry from the now-defunct Powerblogs site.  It is pretty good, I think, and deserves to be kept online. …………. Have I been in existence as one and the same human individual from conception on?  Of course, I and any intra-uterine predecessors I may have had have been genetically human from conception on: at … Continue reading “Zygotic Division: Was I Once a Zygote?”<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[313],"tags":[],"class_list":["post-7846","post","type-post","status-publish","format-standard","hentry","category-abortion"],"_links":{"self":[{"href":"https:\/\/maverickphilosopher.blog\/index.php\/wp-json\/wp\/v2\/posts\/7846","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/maverickphilosopher.blog\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/maverickphilosopher.blog\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/maverickphilosopher.blog\/index.php\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/maverickphilosopher.blog\/index.php\/wp-json\/wp\/v2\/comments?post=7846"}],"version-history":[{"count":0,"href":"https:\/\/maverickphilosopher.blog\/index.php\/wp-json\/wp\/v2\/posts\/7846\/revisions"}],"wp:attachment":[{"href":"https:\/\/maverickphilosopher.blog\/index.php\/wp-json\/wp\/v2\/media?parent=7846"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/maverickphilosopher.blog\/index.php\/wp-json\/wp\/v2\/categories?post=7846"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/maverickphilosopher.blog\/index.php\/wp-json\/wp\/v2\/tags?post=7846"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}