Re: Introduction (Digital Physics)

From: Marchal <>
Date: Tue Jun 26 08:24:16 2001

Joel wrote:

>If we cannot program it... it's not a Theory of EVERYTHING. It's just a

You really should be an intuitionist mathematicien. It is consistent
with most intuitionist mathematical system that

    1) all function from N to N is computable.
    2) all function from R to R is continuous.

In my approach the intuitionist philosophy
correspond to the first person viewpoint.

But I'm a Platonist, at least about numbers and functions from N to N.
This includes a lot of uncomputable functions. For exemple the function
which gives for each n the greatest number you can compute in fortran
with program of length n. (This function grows quickly than any
computable function; you can "approximate" it, in a very weak sense by
using transfinite induction: this illustrates that higher infinities can
help to manage finite combinatorial problems).

>Let us take the realist approach and focus on the things we can actually
>compute fully.

Would you formalise that by the total (defined everywhere) functions from
N to N, or do you accept the partial computable functions as well?
And why would you not accept also the functions computable relatively to
halting problem? They correspond naturally to the function computable in
limit and are quite usefull if you accept infinite histories ...


PS I will comment you other post (from the same thread), where you say
you are a materialist, ASAP.
Received on Tue Jun 26 2001 - 08:24:16 PDT

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