On 18 Jan 2014, at 05:27, LizR wrote:

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On 18 January 2014 17:16, meekerdb <meeke...@verizon.net> wrote: On 1/17/2014 5:40 PM, LizR wrote:But apparently the brain has a lot to do with those computations inPlatonia, c.f. anesthetic. Notice that I'm not a disciple ofPlatonia.Me neither, I am agnostic - but within comp it is assumed, so whilediscussing comp we have to assume it (unless we're rejecting compon that basis). But I can see that Platonia makes sense in that 17does seem to be prime idependently of you and me and everyone else,which is (I'm told) enough for the whole shebang to come into somesort of existence.I don't think you have to buy the equivalence between (17 is prime)is true and (17 is prime) exists. In fact Bruno always says youonly have to believe the first for his argument to succeed. Butthen he slips in the UD and it seems that every truth of arithmeticimplies and existence. I think this is the same problem as step 8.If everything has to be simulated, then there's no differencebetween simulated and real. If I'm "really" existing in aninfinity of world/simulations that are *just like this one up tonow* - then they ARE this one (c.f. Leibniz).Well, I haven't managed to get my head around step 8, at least, notif step 8 is the MGA? (Or maybe I did, if it isn't....)

`May be there is a simpler argument than step 8 (MGA). It is the fact`

`that you need magical (non Turing emulable) matter for a machine being`

`able to distinguish "real matter" (what could be that?) from its an`

`arithmetical emulation.`

`So, even without the MGA, you can understand that the notion of "real`

`matter" can only be a reification of an unknown (real matter) to`

`prevent the use of a simple theory. This makes already the "real`

`matter argument" like a creationist god-of-the-gap.`

`MGA just extends this in showing that not only that "real matter" is a`

`reification, but that it needs some quite ad hoc components. Not all`

`philosophers are against reification, so MGA makes the absurdity of`

`doing that reification (in this context) much more palpable.`

I suppose what I need to know is how the existence (in any sense) ofthe integers and elementary arithmetic operations createscomputations.

`Yes, that is a key point. It is not simple to explain, although more`

`or less standard in mathematical logic.`

`The problem here is that we must distinguish between a computation and`

`a description of a computation, and understand that if RA can prove`

`the existence of a computation only through the existence of a`

`description of a computation, then the computation exists. This is`

`subtle because it needs to see well the difference between syntaxical`

`sentences and semantical statements, ...`

We can come back on this. It is well done in some books.

In fact every possible computation. I believe it's done indexically,whatever that means ... but I think this is about where I start tofeel I shouldn't bother my pretty little head.If the sheer existence of numbers, + and x implies that all possiblecomputations "exist "(in an abstract sense) then it all follows - inan abstract sense.

`Yes, and the concrete experience will exist too, in that abstract`

`sense, and that's is enough for the existence of indexically concrete`

`experience. Tegmark is right on this (but not original in the prior`

`publication sense).`

This brings me back to your comment about equivalence (or not). Thething is, I'd like to know what I'm buying or not buying before Idecide whether to buy it!

`You need to buy only two things: "yes doctor" and Church thesis. AR is`

`implicit in Church thesis (and in the whole of science, I would add).`

Bruno

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