Re: Is It True What They Say About Tarski?

Christian Whitaker (
Fri, 22 May 1998 12:18:11 PDT

>Tony Hollick (
>>(Apologies to Susan Masterman for 'borrowing' her title).
>>I'm mildly surprised that more readers of this list are not fully
>>familiar with logician Alfred Tarski's reconstruction of a commonsense
>>Correspondence Theory of Objective Truth, utilizing a metalanguage,
>>whereby we evaluate the truth content of formal statements concerning
>>objective reality.
>>This following example is a bit more complex than first appears --
>>deceptively simple -- sometimes there is more to the obvious than is
>>obvious... >:-} ).
>>Following Tarski, we may say:
>>'The statement "le ciel est bleu" is true if --
>>and only if --
>>the sky is, in fact, blue.'
>>Thus, we can examine and test the correspondence of statements with
>>objective reality, with the metalanguage serving to avoid tautology,
>>among other things.
> IAN: "Tarskian truth" seems to be exactly
> the case for a definable truth I was making.
> Physical reality is true, and words are true
> to the extent they map onto reality one-one.
> This is also the natural notion of truth,
> since a lie is a report about events in
> the physical world that do/did not exist,
> and thus do not map onto the physical world.
I have a question about how far you can take a Tarskian truth such as
'The sky is blue'. It certainly is some of the time, but towards sunset
it can be orange and red, if it is overcast it can be grey, if it is
nighttime it can be black, and if it is nighttime in the city, some
orange or purplish color. If an H-bomb goes off nearby, it will be
blindingly white just like everything else. If you are colorblind, it
will be grey. It may be blue now, but if the sun goes out tonight, it
will never be blue again. From what perspective does one decide whether
the statement "le ciel est bleu" can be truthfully mapped onto the
objective world? From the viewpoint of the observer? This merely says
that people have subjective views on the state of the world. If a
sighted man says "le ciel est bleu" to a colorblind man and a blind man,
one will disagree or consider it a difference of opinion, and the other
one will have to accept it as hearsay.

Christian Whitaker

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