# Re: [quickphilosophy] Re: Fodor on Concepts IV: Circularity + Peacocke

• From: wittrsl@xxxxxxxxxxxxx
• To: quickphilosophy@xxxxxxxxxxxxxxx
• Date: Thu, 30 Sep 2010 14:03:52 -0700 (PDT)

```Hi Walter:

I'm not sure I get that argument either. It seems to me that Peacocke is very,
very careful to just put down the primitive forms that the person who might
have a CONJUNCTION concept has to assent to. So, for example, if Prof. P
well, I'd say p. So P asks, is that all? Q replies, well, I could say q. And,
so forth. It just shows a low-level inclination to follow the pattern. There
must be some mental constructs inside Q's head that control this behavior, but
it's at least conceivable that Q can't make the leap to confirm that he's
following the C rules of inference because he has the concept of CONJUNCTION. Q
just does it.

On the other hand, if we try to use Q's notion of truth and explain CONJUNCTION
to Q that way, then Prof. P has to say something like "p AND q is true if and
only if p is true AND q is true". But that way Prof. P is using AND to define
AND. Now, this is how you do it in mathematical logic. You have a formal
language and an interpretation on a structure, the model, and the predicates in
the language are interpreted by versions of themselves on the model. So it's
sort of circular. Why do we say that the axioms of arithmetic are modeled by
the natural numbers? Well, because the successor function S in the theory has
an interpretation that is the successor function on the natural numbers! You
talk about the natural numbers in your metalanguage, and you study the formal
theory with its syntax for sentence formation, its logical and nonlogical
axioms, and its rules of derivation using that metalanguage...which has the
"same" things in it as the formal theory.

It appears to me that Fodor has to argue something more. He has to show that
somehow, Peacocke has to employ CONJUNCTION along with the experimental subject
in order to see if the subject can follow the C schema, that thing with p, q,
C, and the horizontal lines, the rules of introduction and elimination for the
C-symbol. But, as I see it, all Peacocke has to do, and all that he says he
wants to do, is to just use the subject's language, the word for CONJUNCTION,
be it 'und' or 'et' or 'y' or 'kai' or 'and', and then see if the subject Q
follows the schema.

What if we considered some other logical operator like NOR? or NAND? or XOR?

I need to reread this again and see if I can align myself with Fodor.

Thanks!
--Ron

--- On Thu, 9/30/10, walto <calhorn@xxxxxxx> wrote:

From: walto <calhorn@xxxxxxx>
Subject: [quickphilosophy] Re: Fodor on Concepts IV: Circularity + Peacocke
To: quickphilosophy@xxxxxxxxxxxxxxx
Date: Thursday, September 30, 2010, 10:57 AM

If it's any consolation, I think that section is difficult too, Ron.

I mean, do you understand his argument to the effect that defining logical
constants via the form of statements (i.e., presumably, via truth-tables) is
somehow circular? I didn't get that. I take it that he's claiming that grasping
the requisite forms requires understanding the concepts they're supposed to
explain (like AND or OR or NOT) but I don't see why he thinks that's so. I see
that the notion of TRUTH is required, but not those of the logical constants.

W

```
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