Re: Logic must "look after itself"

translogi wrote:
On 8 Sep, 21:24, John Jones <jonescard...@xxxxxxx> wrote:
translogi wrote:
Found your quote
it is in the tractatus
5.473 Logic must look after itself. If a sign is possible , then it is
also capable of signifying. Whatever is possible in logic is also
permitted. (The reason why 'Socrates is identical' means nothing is
that there is no property called 'identical'. The proposition is
nonsensical because we have failed to make an arbitrary determination,
and not because the symbol, in itself, would be illegitimate.) In a
certain sense, we cannot make mistakes in logic.
I think Wittgenstein was also wrong here.
He like Russell was very into what we now call classical logic,
(inclusdes the law of the excluded middle )
Classical logic at that time was still very new.
Wittgenstein was also very in to truthtables and thought that every
logical statement can be SHOWN to be true by a truthtable
Guess we now know better
What do you think is logic?
I don't know about Witts truth tables, but I certainly doon't think that
we now know better if that's Godels doing.

I thought logic was about reducing instances to general cases and
presenting it in a way that copies the physical presence of physical
objects, using brackets, single letters (often where each letter counts
as an one object), etc. This helps in bulk calculation, just like
arithmetic.- Hide quoted text -

- Show quoted text -

That is a quite fairly description of logic "reducing instances to
general cases"
But there is allways the problem of the validity of the reduction.
and after generalisation you have stopped talking about concrete
physical objects.

you are allready talking about universals.

like 1+1 = 2 is not about oranges or apples anymore

The thing is that from (Only conrete physical objects it is hard to
draw general conclusions
this white cube is soluable in water
this white cube is soluable in water

generalisation
all white cubes are soluable in water

therefore
that white cube is soluable in water?

(if you are unaware that the first is sugar the second is salt and the
third is made of eggwhite )

while
this cube of white sugar is soluable in water
this cube of light brown sugar is soluable in water
generalisation
all sugar cubes are soluable in water

therefore
that dark brown sugar cube is soluable in water

why is the first generalisation invalid and the second valid?
(whithout reference to color or substance)




Yes, but I think that if objects are all the same in being supported by, or found in, the same framework then we would not expect them to behave the same. The large object won't fit behind the small object etc.
.

Relevant Pages

  • Re: Logic must "look after itself"
    ... and after generalisation you have stopped talking about concrete ... this white cube is soluable in water ... (if you are unaware that the first is sugar the second is salt and the ...
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  • Re: Logic must "look after itself"
    ... and after generalisation you have stopped talking about concrete ... this white cube is soluable in water ... this cube of light brown sugar is soluable in water ...
    (sci.logic)
  • Re: Logic must "look after itself"
    ... and after generalisation you have stopped talking about concrete ... this white cube is soluable in water ... this cube of light brown sugar is soluable in water ...
    (sci.logic)