On Sat, Feb 04, 2012 at 01:22:10PM +0100, Bruno Marchal wrote:
> On 03 Feb 2012, at 23:24, Stephen P. King wrote:
> >
> >    I am not missing a thing, Bruno. You are missing something
> >that is obvious to the rest of us.
> If someone else can confirm this, and put some light on what Stephen
> is saying, I would be pleased.

Having had some skype discussions with Stephen, I believe Stephen is
referring to "that which breathes fire into the equations", as Hawking
puts it.

We all agree that COMP does not posit any particular "fire breather" -
any entity capable of universal computation will do. Bruno selects
Peano arithmetic as a sufficient system (PA supports universal
computation), for pedagogical reasons, although he'd really rather use
combinators, which would also suit the purpose, but are less known.

Stephen is objecting that such abstract systems are, well, too
abstract. He'd prefer something more concrete - whatever "concrete"
might actually be. It is true, I understand, that the UDA (and AUDA) does
not eliminate the possibility of a "concrete physical
underpinning". It is just that such a concrete physical underpinning has
no measurable, or detectable effect on our phenomonology other than
that due to its capability of universal computation.

Which is why I'd like to remind people of Witgenstein's comment: Whereof
one cannot speak, thereof one must be silent.


Prof Russell Standish                  Phone 0425 253119 (mobile)
Principal, High Performance Coders
Visiting Professor of Mathematics      hpco...@hpcoders.com.au
University of New South Wales          http://www.hpcoders.com.au

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