From: denmckinnon@halls1.cc.monash.edu.au (NEIL MCKINNON)
Subject: Re: Having to believe
Organization: Halls of Residence, Monash University 
Date: Thu, 30 Jul 1992 03:48:50 GMT

In article <1992Jul28.150210.1@sara.cc.utu.fi> jhaukioj@sara.cc.utu.fi writes:
>From: jhaukioj@sara.cc.utu.fi
>Subject: Re: Having to believe
>Date: 28 Jul 92 15:02:10 GMT

>In article <denmckinnon.1.712262892@halls1.cc.monash.edu.au>, 
>denmckinnon@halls1.cc.monash.edu.au (NEIL MCKINNON) writes:
>> Gary Merrill writes:-
>> 
>>>There are many (non-isomorphic) mappings that may be used successfully.
>>>It does not follow from this that *any* mapping is "correct".  The
>>>anti-realist does not believe that *anything* goes, but rather that
>>>there is no particular mapping with a special claim to preferred status.
>>>The world is really out there -- under one or another description.
>>>There are a number of "right" descriptions you may pick.  But there are
>>>*wrong* descriptions as well.  Choose one that is wrong enough and you
>>>are dead meat.  In this sense, indeed, "Right thinking or bust."
>>>-- 
>> 
>> I was wondering what the important differences are between your anti-realist 
>> position here and a realist position.  My reading on this topic is probably 
>> fairly limited, but as far as I can see the anti-realism of, say, Dummett 
>> and Putnam is ultimately based on intuitions that truth ought not be non-
>> epistemic.  Their semantics for truth seemed quite similar to me.  For 
>> Putnam, a sentence is true only if it is part of an Ideal theory (i.e one 
>> that maximally satisfies observable evidence and maximally satisfies our 
>> constraints on theory acceptance, like simplicity).  For Dummett a sentence 
>> is true only if it is conclusively verifiable (which comes to it being a 
>> sentence in an Ideal Theory of the Universe).  Once you make truth 
>> epistemic, what you are left with is some sort of coherence theory of truth, 
>> whereby any consistent set of beliefs is true.  The objection to this is

>Not *any* consistent set of beliefs. The body of beliefs must also be
>consistent with observations. Maybe this is what you meant, but then it would be
>more reasonable to talk of judgements instead of beliefs.

Yes, I was wrong to say that Putnam's view of truth simply reduces to a 
coherence theory.  Clearly it does not.  What I should have said, 
rather, is that it is ultimately open to the same objection, due to 
the fact that we may never be able to single out one theory in particular 
as ideal, and further, that there may be a number of theories which are 
contradictory yet indistinguishably ideal. 


>I don't see why this should worry the anti-realist too much, because s/he 
>is not saying that we have a free choice between different (consistent) 
>sets of beliefs or conceptual systems. What the anti-realist (at least of the 
>Putnamian type, if I am not mistaken) *is* saying is that we can't 
>judge the truth or falsity of our beliefs outside the scheme of 
>description that we are using. This seems to me to suffice to counter
>the above objection that anti-realism would lead to the possible 
>truth of (~A & A). This objection makes sense only if we assume that
>there might be different ideal theories which would all be consistent with all
>possible evidence. Even then I don't see any guarantee that the negation of a
>true judgement in one such theory would even necessarily be expressible in
>another. And even if it were, this need not worry the anti-realist, because
>*inside* an ideal theory, (~A & A) can not be true.

I don't think you have really answered the objection.  I was talking 
meta-theoretically, and what you have suggested in the last sentence is 
merely that from the perspective of a particular theory, a contradictory 
theory cannot be true.

 >> to me to reduce to a coherence theory, since there may be many 
internally >> consistent theories which equally satisfy all constraints on 
acceptance and >> yet are inconsistent with each other.  This is so because 
an ideal theory is >> not something we have epistemic access to any more 
than an "external >> reality".  Consequently these semantics do not make 
truth any more >> accessible than a realist conception of truth.

>I think they do. On any sensible anti-realist conception of truth, a true 
>judgement needs to be consistent with observable evidence. This seems to me to
>ensure that e.g. the belief that I am now sitting by a computer is true,
>because I don't see how any theory (in a loose sense) could be observationally
>adequate unless it implied the truth of this belief.  

As far as I can tell, Putnam *must* say of a sentence that it is true if and 
only if it is true of an ideal theory.  This is to avoid an objection Putnam 
himself raised against Dummett (in Reference and Understanding).  Dummett at 
one stage wanted to say that a sentence is true if and only if it is "
warrantedly assertible".  The objection to any anti-realist criterion for 
truth which is less than "conclusively verifiable" or "true in an ideal 
theory"  is that a sentence of a certain type, or a theory, can be true at 
one time and then false later on (or simultaneously by separated 
societies in the same world).  So the sentence "The tree-god exists and 
controls the elements" may have been true 15000 years ago when a tribe held 
this belief and it seemed warranted to them.  However it is not true today, 
since the Tree-god theory does not explain observational evidence well now.  
But it was true then!

As far as I can tell, Putnam must also add this property to an ideal theory: 
not only must it maximally explain all observational evidence, but it must 
explain all *possible* observational evidence.  This addition ensures that 
there cannot be a host of contradictory ideal theories, all true at 
different times, which maximally explain all observable evidence possessed 
at their respective times.  Now, in 
addition to possibly not being able to distinguish between certain 
prospective ideal theories when we have all possible observational evidence, 
there is the problem of knowing *when* we are in possession of all 
observable evidence.  And it seems to me that this is an insoluble problem.

Hope this makes sense!

Neil.