[hist-analytic] Roger's Questions about Anayticity

Danny Frederick danny.frederick at tiscali.co.uk
Wed Jan 28 05:42:00 EST 2009

Hi Roger,

I'd like to add three things to my last message.

First, I gave as an example of a necessary truth 'Hesperus = Phosphorus.'
That, of course, was a mistake: in worlds in which Hesperus does not exist,
it is false that Hesperus = Phosphorus. But the mistake is easy to rectify.
Just replace 'Hesperus = Phosphorus' with 'Hesperus exists if and only if
Hesperus = Phosphorus.'

Second, when I said that we should reject the a priori-empirical distinction
for Duhemian reasons, I was not endorsing Quine's 'holism,' which I think is
nonsense. Duhem ('The Aim and Structure of Physical Theory') showed that we
need a large number of theories to derive an empirical prediction, so that,
if the prediction is falsified, we have to decide which of these theories we
are going to modify or replace; I think (from memory) that he also pointed
out that replacement of one of these theories will in its turn typically
require rejection or replacement of other parts of our background knowledge.
But all of this falls very far short of the untenable claims that ALL our
knowledge is involved whenever we test a theory and that consistency with a
test report can be achieved by making changes ANYWHERE in our knowledge. In
'Two Dogmas' Quine seems to shift between the reasonable claims that Duhem
made and the more extreme claims that I just said are untenable; or,
perhaps, he MAKES the more modest claims but SUGGESTS the extreme ones.

Third, I can suggest a text to consult about the issue of necessary truth
and interpreted versus uninterpreted sentences, namely, Martin Davies,
'Meaning, Quantification, Necessity.' I do not have a copy, but I read it in
1986 and I thought it was excellent. I am only guessing, though, that it
will contain a relevant discussion (I cannot check myself, as I do not have
access to a library and even second-hand copies of the book sell for an
exorbitant price). If you are able to consult the book, I should point out
that there is a mistake in it. From memory, the mistake comes quite late.
There is a complex formula which appears twice on the same page. The second
occurrence is the mistake: a somewhat different formula should be there
instead. If you have followed the book to that point, it should be obvious
how to amend the printed formula. I brought this to the attention of Martin
Davies in 1986: he confirmed the error, which he said was due to the

Best wishes,


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