Since parts of the brain are recycled every few days does that mean that materialistic theories of consciousness don't work?

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    $\begingroup$ How does any other body part work, when the actual matter is generally recycled over shorter or longer periods? FTM, how does your car keep running when you have to keep filling the gas tank, replacing tires, batteries, & other parts? If you kept it long enough that you eventually had to replace every single part, wouldn't it still be a running car? $\endgroup$ – jamesqf Nov 12 '17 at 19:01
  • $\begingroup$ Notice that the link you provide concerns development, where plenty of things change. You have added a tag for proteins but do not really discuss the implication of protein turnover given the prominent role that modern neuroscience gives to translation-dependent synaptic plasticity. @jamesqf The question is not how can the brain work given the turnover, but if we can for example claim that a person is the same over time. Or put differently, how much of this turnover is critical for "consciousness". If none of it is, then "consciousness" cannot reside in matter, or so the argument goes. $\endgroup$ – vkehayas Nov 12 '17 at 21:05
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    $\begingroup$ @vkehayas: The turnover/consciousness argument is, at least to me, so obviously false ("not even wrong" comes to mind :-) that it's actually hard to think of how to refute it. But consider a computer as an analogy. With RAID storage, you can replace one of the hard drives (often hot-swapping while the computer is running), and all the data will remain unchanged. Over time, you could replace all the disks. With a largish cluster, you can swap out CPU nodes while programs are running, and (if properly designed) they'll continue working just fine. (Continued...) $\endgroup$ – jamesqf Nov 13 '17 at 5:15
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    $\begingroup$ ... The programs (and presumably consciousness - not that I'm claiming to know what that is) are PROCESSES that aren't tied to specific bits of matter. You can replace the underlying hardware, whether it's silicon chips or proteins, and the process continues unaffected. $\endgroup$ – jamesqf Nov 13 '17 at 5:15
  • $\begingroup$ What is consciousness? $\endgroup$ – user37894 Nov 13 '17 at 15:58

That was an interesting read, and I saw nothing to support your statement that "brain parts die every few days".

Neural plasticity demands that some synapses degrade as new ones are formed. But there are (an estimated) 100+ trillion synapses (some put it an order of magnitude higher) so, really, a few here and there means little. It's when there is wholesale loss that problems arise.

A strong argument for a materialist theory of consciousness is that as neurons involved with memory die, so does memory. This is evident in the transition that occurs in early childhood allowing for the formation of long term memory as well as the degradation of short-term memory and other brain functions in people with, say, Alzheimers.

Hippocampal Neurogenesis Regulates Forgetting During Adulthood and Infancy Science 9 May 2014


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