tag:blogger.com,1999:blog-3891434218564545511.post5225198871049394896..comments2024-03-27T20:37:09.185-05:00Comments on Alexander Pruss's Blog: Rapid cell replacement: A failed argument against materialismAlexander R Prusshttp://www.blogger.com/profile/05989277655934827117noreply@blogger.comBlogger2125tag:blogger.com,1999:blog-3891434218564545511.post-82490647136146412402017-05-02T22:25:00.238-05:002017-05-02T22:25:00.238-05:00I am not sure. At least, I think in Plantinga'...I am not sure. At least, I think in Plantinga's version (in "Materialism and Christian Belief"), the failure of the argument is easier to see. Plantinga says the replacement can happen "[i]n a period of time as brief as you please." But that is implausible to the materialist. The materialist should not accept that a replacement brain half becomes a part of you as quickly as one pleases. Presumably the replacement brain half gets incorporated into your body first at the joint and then the demarcation of the incorporation moves towards the other side of the hemisphere no faster than at the speed of light. So it takes a certain minimum time, at least a quarter of a nanosecond, for the whole half to be incorporated. Moreover, it is quite plausible that it takes a bit longer--for incorporation plausibly there needs to be significant causal back-and-forth, and in the brain that happens at rather less than the speed of light. <br /><br />So I think the materialist can reasonably say that when you replace a whole brain half, there is a gap in your conscious train of thought until that half is incorporated into you.<br />And if the other half is replaced before the first one is sufficiently incorporated, then you don't survive. <br /><br />On the other hand, it is not as plausible that a single cell replacement produces a gap in your conscious train of thought.<br /><br /><br />Of course, all this still leaves a challenge to the materialist to account for what constitutes incorporation--just how much causal back-and-forth is needed before a replacement part becomes a part of the whole? Some (but not all) dualists can meet this challenge nicely by saying that a part of the body comes to be incorporated not in virtue of causal back-and-forth between that part and the rest of the body, but in virtue of the right kind of metaphysical relation between that part and the soul (the informed-by relation, in the case of the hylomorphic dualist).Alexander R Prusshttps://www.blogger.com/profile/05989277655934827117noreply@blogger.comtag:blogger.com,1999:blog-3891434218564545511.post-32078936560459337292017-05-02T21:52:21.965-05:002017-05-02T21:52:21.965-05:00Pretty much this same argument is in Plantinga, &q...Pretty much this same argument is in Plantinga, "Materialism and Christian Belief" and maybe some other places (I seem to remember it in _Nature of Necessity_).<br /><br />Heath Whitehttps://www.blogger.com/profile/13535886546816778688noreply@blogger.com