[hist-analytic] L-truth, A-truth: Carnap and Grice

Roger Bishop Jones rbj at rbjones.com
Mon Mar 8 12:52:36 EST 2010

On Monday 08 Mar 2010 14:33, Bruce Aune wrote:
> As I see it, the following quotation from RBJ, though
>  true, is misleading:
> "at the last in the Schilpp volume he [Carnap] concedes
>  defeat to the  Quine-Tarski conspiracy on use of the
>  term "Logical Truth" and starts using  A-true instead of
>  L-true. In "Meaning Postulates" he seems to use the "L-"
>  concepts throughout."

Yes, I was on my way to confessing my error, when I found 
your message.
Its true (as I had said) that Carnap does use only L- 
concepts in "Meaning Postulates", but he has already fallen 
into line, at least for the purposes of this exposition. 
with Quine, and is now using L- concepts for the narrow 
notion of logical truth.

Carnap talks here, JL, of logical "particles".

> In "Meaning Postulates" Carnap did use "L-true" in
>  relation to meaning postulates, but he never considered
>  a meaning postulate L-true or L-false simpliciter.

Yes, I agree. Though it would have been under the previous 
meaning for L-true (had he not made an error in this respect 
which this paper is correcting).  The correction of the 
error in his definition of analyticity (which mirrors one in 
the Tractatus) does not depend on the shift in terminology 
with which here here concedes on terminology to Quine.
(i.e. the use of L-true for "the narrower conception" of 
logical truth).

>  His idea was that a sentence S is analytic in L just
>  when P  L-implies S, P being the conjunction of the 
>  meaning postulates for L.

Yes, this he gives as the explicandum of "L-true with 
respect to P".

>  He extended this harmless way of
>  talking by associating with L a language L' in which
>  sentences of L can loosely be described as L-true: they
>  are L-true in L' if they are L-implied by P.

This is an odd little alternative, he would have been better 
not to mention it.

>  But  describing other P-consequences as L-true in L' is
>  bound  to produce confusion in careless readers. For this
>  reason, Carnap began to speak of P-consequences as
>  A-truths.

That's an interesting explanation of the introduction of the 
term.  But I don't see how it helps to reduce the confusion 
arising from that manner of defining analyticity, which can 
only be fixed by dropping the alternative definition.

>  Since L-truths (narrowly understood) are,
>  trivially, consequences of P, they too can be described
>  as A-true, but this is unlikely to cause the kind of
>  confusion prompted by his earlier terminology.

So which earlier terminology is it that you consider 

My understanding is that the primary purpose of the "Meaning 
Postulates" is to correct an error in "Meaning and 
Necessity" which Carnap had inherited by following the 
Tractatus too closely in its definition of logical truth.
(this is definition 2-2).  For this purpose a change in 
terminology is unnecessary, and does not help, though in the 
circumstances it was an understandable concession.


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