[hist-analytic] Carnap and Grice on "logical"

Roger Bishop Jones rbj at rbjones.com
Thu Mar 4 07:08:47 EST 2010

On Thursday 04 Mar 2010 06:25, Jlsperanza at aol.com wrote:

> I see, in  a way, I was going to say it relates to Grice
>  (That's what  I _always_ say, right?). But on second
>  thoughts, I realise Grice speaks, somewhat irritatingly,
>  but I love him, of
> -, &, v, ->, (x), (Ex), ix
> as "formal devices" -- not "logical devices".
> I always thought the correct is "constant", but you may
>  teach me out of that!

No, not at all.  It was Witters who was adamant that the 
logical constants aren't constants.

Actually whether the terminology is appropriate depends on 
the particular formal language you are talking about, since 
most of them make use of the concept "constant" but they 
differ in what things are constants.
So in HOL all the usual suspects really are logical 
constants (names which denote entities),
So you can say things like:

	(Ex)(x = $/\)

Where the "$" is use to suspend the usual lexical status of 
conjunction and allow you to use it (not mention it) without 
supplying two things to conjoin.

However, in first order logic, none of the logical operators 
are constants.

In natural languages, who knows?


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