On 11 Feb 2010, at 06:46, Jack Mallah wrote:

It's been a very busy week. I will reply to the measure thread (which is actually more important) but that could be in a few days.

--- On Thu, 1/28/10, Jason Resch <jasonre...@gmail.com> wrote:
What about if half of your neurons were 1/2 their normal size, and the other half were twice their normal size? How would this be predicted to effect your measure?

If it had any effect - and as I said, I don't think it would in a QM universe - I guess it would decrease the measure of part of your brain and increase that of the other part. That may sound weird but it's certainly possible for one part of a parallel computation to have more measure than the rest which can be done by duplicating only that part of the brain. See my paper on partial brains:


--- On Thu, 1/28/10, Stathis Papaioannou <stath...@gmail.com> wrote:
Do you think that simply doubling up the size of electronic components (much easier to do than making brains bigger) would double measure?

The effect should be the same for brains or electronics.

You could then flick the switch and alternate between two separate but parallel circuits or one circuit. Would flicking the switch cause a doubling/halving of measure?

If the circuits don't interact, then it is two separate implementations, and measure would double. If they do interact, we are back to 'big components' which as I said could go either way.

Would it be tantamount to killing one of the consciousnesses every time you did it?

Basically. Killing usually implies an irreversible process; otherwise, someone is liable to come along and flick the switch back, so it's more like knocking someone out. If the measure is halved and then you break the switch so it can't go back, that would be, yes.

--- On Thu, 1/28/10, Bruno Marchal <marc...@ulb.ac.be> wrote:
Does the size of the components affects the computation?

Other than measure, the implemented computation would be the same, at least for the cases that matter.

So, the behavior would not change, but the consciousness would be different? A little thin brain would produce a zombie?

I don't assume the quantum stuff. It is what I want to understand. I gave an argument showing that if we assume computationalism, then we have to derive physics from (classical) computer science

Of course I know about your argument. It's false.

I guess you mean invalid. What is invalid in the reasoning? Have you follow the last year new exposition on this list MGA (Movie Graph Argument). I have understood eventually that we don't need to use the counterfactual analysis à-la-Maudlin. MGA is more general (and older). The only way to escape the conclusion would be to attribute consciousness to a movie of a computation, but this forces to confuse a computation (relation between numbers, or combinators) and a description of a computation (like a Gödel number of a (finite) piece of a computation). Those things are related, but different.

You wrote convincing posts on the implementation problem. I thought, and still think, that you understood that there is no obvious way to attribute a computation to a physical process. With strict criteria we get nothing, with weak criteria even a rock thinks.

The implementation problem is: Given a physical or mathematical system, does it implement a given computation? As you say, if the answer is always "yes" - as it is on a naive definition of implementation - then computationalism can not work.

This was an important problem - which I presented a solution for in my '07 MCI paper:


What you call computationalism is a form of physicalist computationalism. The Movie graph argument show it is inconsistent with "yes doctor + Church thesis" and "yes doctor" follows from the physicalist computationalism assumption. And as you know, physicalist computationalism raises the implementation problem.

So I now consider it a solved problem, using my CSSA framework. The solution presented there does need a bit of refinement and I plan to write up a separate paper to present it more clearly and hopefully get some attention for it, but the main ideas are there.

But that's only half the story. There is still the measure problem: Given that a system does implement some set of computations, what is the measure for each? Without the answer to that, you can't predict what a typical observer would see. This problem remains unsolved (though I do have proposals in the paper) and relates to the problem of size.

The measure is determined relatively by the universal machine by the set of the maximal consistent extensions of its beliefs. The Gödel-Löb- Solovay logics of self-reference provides the math, and explains how the "coupling consciousness realities" emerges from the numbers.

-- Bruno Marchal


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