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From: ladkin@kestrel.ARPA (Peter Ladkin)
Newsgroups: net.math,net.philosophy
Subject: Re: Tarski's definition of truth
Message-ID: <5900@kestrel.ARPA>
Date: Mon, 17-Mar-86 16:20:29 EST
Article-I.D.: kestrel.5900
Posted: Mon Mar 17 16:20:29 1986
Date-Received: Wed, 19-Mar-86 04:42:19 EST
References: <12411@ucbvax.BERKELEY.EDU>
Organization: Kestrel Institute, Palo Alto, CA
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In article <12411@ucbvax.BERKELEY.EDU>, tedrick@ernie.berkeley.edu (Tom Tedrick) writes:
> Can someone explain Tarski's definition of truth to me?
> I never quite understood it.

> The statement 'Grass is green' is true iff grass is green

There's much more to Tarski's theory than this, but to start
here:

The left hand side ascribes truth to a certain sentence,
and the right hand side describes a fact about the world.
The statement asserts that the sentence is true iff the
fact holds.
This is not a *theory* of truth, but a condition of adequacy
that any theory of truth has to fulfil.
Tarski wanted to ascribe truth to sentences, via the notion
of satisfaction of formulae (sentences with object-place-holders).
He was able to explain how a sentence with multiple quantifiers
can inherit its truth value from its parts, something which had
puzzled logicians from Aristotle onwards.

The best way to start is to read the original article,
"The Semantic Conception of Truth" in his collection
"Logic, Semantics, Metamathematics", easily obtainable
from the UCB Philosophy Library.

Peter Ladkin