# Re: Only logic is necessary?

```
Brent Meeker wrote:
> Bruno Marchal wrote:
> > Le 05-juil.-06, à 15:55, Lennart Nilsson a écrit :
> >
> >
> >>William S. Cooper says: "The absolutist outlook has it that if a logic
> >>is valid at all it is valid period. A sound logic is completely sound
> >>everywhere and for everyone, no exceptions! For absolutist logicians a
> >>logical truth is regarded as 'true in all possible worlds', making
> >>logical laws constant, timeless and universal."```
```
Of course "logical laws are true in all logically possible worlds"
is a (logical) tautology. An "X-possible world" is just a hypothetical
state of affairs that does not contradict X-rules (X is usually
logic or physics).

> >>Where do the laws of logic come from? he asks the absolutist.
> >>Bruno

First you have to ask if they could possibly have been different.
Then you have to ask what notion of possibility you are appealling
to...

> >
> >
> >
> > If you believe in the more primary notion of arithmetical truth (for
> > example if you believe that proposition like "317 is prime" are
> > independent of you) then you can justify classical logic by the Plato
> > Realm (perhaps limited to numbers and their relations), and the many
> > logics will be filtered through the "mind" of the consistent extension
> > of machines.
> > Classical logic is the best tool machines can have to go beyond
> > classical logics.
> > But logic and logics are not fundamental, with comp those emerge from
> > numbers. And nobody knows where numbers come from,
>
> Cooper says that numbers "come from" the evolutionary advantage of being able
> to count.  Of course
> that doesn't explain where big numbers come from, or even whether they exist.

Being able to count doesn't remotely mean
numbers exist. It mean certain organisms can calculate, follow rules,
compute.

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