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There are disturbing ideas in the Feb 21, 2011 Time magazine cover article 2045: The Year Man Becomes Immortal. The article attributes to Raymond Kurzweil the prediction that within the next 25 years personal computers will possess the processing power and storage capacity to allow humans to "scan our consciousnesses into computers."

Does Judaism claim the brain as the seat of the soul? If so, and I'm able to download my brain into a computer, does that mean "I" (i.e. my soul) can outlive my body? Could this state of existence fulfill any of the ideas contained in the Messianic Age or The World To Come (a purely spiritual existence)? Can one then mix souls together by mixing together the bits of their brains? What is the Jewish definition of consciousness?

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Right off the bat. We follow Maimonides' codification: the Messianic Era will be a physical one very similar to our own world; the change is geopolitical. So it's a World To Come question, not a Messianic question. –  Shalom Feb 28 '11 at 19:57
I'm not so sure about that. There are opinions - I know that the Lubavitcher Rebbe zt"l used to talk about this a lot, and I don't think it was his original idea - that there will be two stages in the era of Moshiach: one where "the world will go on functioning as it always has," and a second one where the natural order will change. –  Alex Feb 28 '11 at 20:36
I can't answer the question, except to say that the brain appears to be the seat of the soul (or at least the n'shama, perhaps not the other souls or parts of the soul or whatever they are) according to the prayer recited before donning t'filin (it says "the n'shama in my moach ", where I believe moach means "brain" (though it's used for "marrow" also)). –  msh210 Feb 28 '11 at 20:50
Shouldn't the question here really be "Is the body the seat of the soul?"? This has nothing to do with the brain except that it has the highest concentration of neurons in the body. The real questions come at the end, where consciousness is addressed in general terms. These questions are equally valid if the soul is housed in the foot. –  WAF Oct 2 '11 at 19:30
I don't understand how copying the "seat of the soul" can affect the soul itself. If I seat on a chair, and you make one more copy of that chair - should it mean that from now there are two copies of me that seats on both chairs?! –  jutky Oct 2 '11 at 20:09
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3 Answers

First of all, like Shalom noted, these issues with souls and spirituality are not associated with Yemos HaMashiach according to the view we adopt from the Rambam and many others.

I'm not exactly sure what you're looking for, but perhaps the following will help you:

The brain, or what one might call the "intellect" is definitely a core part of what we consider the soul. See Ramban (Genesis 2:7) who brings the well-known dispute between Ibn Ezra and Rambam, both of whom hold that the soul comprises of three parts: (1) living organism (like any other plants/animals), (2) living being (like animals in particular), (3) living intellect (specific to humans).

The Gra interpreted this as three parts of being a "human being" associated with three parts of the human body. The liver representing (1) called "nefesh"; the heart representing (2) called "ruach"; and the brain representing (3) called "neshama".

Hopefully this helps you define what is called the soul, and the part the brain plays in the definition.

EDIT: I recently came into contact with Nishmas Chaim, by R' Menashe ben Yisrael, in which he discusses extensively many issues like this related to the soul and reincarnation with a very logical/philosophical approach. You might be interested in looking at it. (Or specifically the part where he deals with the "seat" of the soul.)

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R' Natan Slifkin has done a great deal of writing on this topic in the past few months, in the context of analyzing whether brain death should be considered Halachic death, on his blog. Here are three posts that deal specifically with the "seat of the soul."

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I would take Time magazine and Kurzweil with a large grain of salt. Kurzweil think because computers have increased in certain physical measurements that they'll soon be just like humans. But there's a lot more to a human than just RAM and GHz. So far, all computers have been able to do is carry out lots extremely precise instructions very quickly. But they have not been able to think of new ideas, and obviously have no self-awareness or consciousness.

Judaism does not make a definitive claim about where the soul is, but its obvious nowadays that a person's thoughts are connected to his brain. You won't be able to download your brain to a computer, and that will not be the World to Come. And there's no need to mix souls.

However, computers can serve as a mashal in understanding these issues. For example, just as one can backup data on a computer, perhaps there's a "spiritual backup" of a person's consciousness elsewhere which is where life-after-death continues. Otherwise, one can take a dualistic approach which places consciousnesses/soul/freewill as external to the physical brain, and separate from the many functions of the brain.

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