From Wikipedia,
Brain in a vat:
Read this very carefully.
Quote:
Since the brain in a vat gives and receives exactly the same impulses as it would if it were in a skull, and since these are its only way of interacting with its environment, then
it is not possible to tell, from the perspective of that brain, whether it is in a skull or a vat.
I don't think it helps any solipsist-type argument of unreality to introduce ideas about a so-called “brain in a vat”. It's just begging all the same questions all over again. For example -
Firstly, how did any brain ever get into any such “vat” in the first place? What is the explanation for how that brain can ever exist at all if it is not a real thing as part of a real world?
… what ever produced that brain? Where did it come from?
… what is the cause of any thoughts at all in any such brain?
… how are it's thoughts produced?
Proposing the existence of a brain (in a vat or anywhere else), immediately admits the need for reality … it is assuming from the very start that a real brain does exist (it's also assuming some sort of real environment called a “vat”). That's really an end to any argument for non-reality from a brain in a vat … unless of course your Wiki quote (or you, or any philosopher) can explain how a functioning thinking brain can exist without any cause?
However, there is also a second problem with that “brain in a vat” idea as given in that Wiki quote – it says “it is not possible to tell...”, but that wording is actually implying an unspoken demand for proof or certainty that the real world exists … it's really saying “it's not possible to tell, for sure”. And we have already said from the start of this thread, that neither science nor anyone here is claiming anything so literally certain as a “proof” of anything at all in this universe (let alone a proof that reality itself exists).
So … if you are going to claim a brain in a vat, then you will need to explain how any such brain ever came into existence in the first place (not to mention also explaining how a brain of any type can produce any thoughts without real chemical reactions arising from a real sensory system).
From Wikipedia,
Brain in a vat:
Read this very carefully.
Quote:
Since
the argument says one cannot know whether one is a brain in a vat, then one cannot know whether most of one's beliefs might be completely false. Since, in principle, it is impossible to rule out oneself being a brain in a vat, there cannot be good grounds for believing any of the things one believes; a skeptical argument would contend that one certainly cannot know them, raising issues with the definition of knowledge.
If there is anything that you disagree with, it indicates a lack in your understanding of the argument.
I'm willing to clarify anything specific that you have a problem with, but I cannot make you understand the argument, you have to do that for yourself, it might need effort.
Remember the "brain in a vat" is an example to illustrate an unassailable argument, the same one I've been trying to explain to you.
Well that second Wiki quote (directly above) actually specifically does say exactly what I just pointed out as an “unspoken demand for proof” in the previous Wiki quote! That is – look at the highlighted sentence above where is says right from the start
“one cannot know" … but how many times do we have to explain to you (and to David Mo and Larry) that neither science nor anyone here is claiming to have a literal “proof” that what we detect is indeed certain to be “reality”. There is no such certainty or proof, either for this issue or for anything at all … you cannot actually prove that QM or Relativity or Evolution is a “fact”.
As I said for the first quote, and as your second quote now makes explicitly clear – your brain in a vat idea is actually a demand for the impossibility of literal proof … it's also a completely untenable and baseless construct anyway, unless and until it can explain how any such real brain can exist if no reality (such as a real brain!) exists!