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IRC chat: What is truth? - #virus, Tuesday 20:00 CST
« on: 2003-04-22 21:03:01 » |
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IRC chat: What is truth? - #virus, Tuesday 20:00 CST
As the time for our scheduled IRC chat approaches, here are a few notes. The following wikipedia entry has been suggested as essential reading:
www.wikipedia.org/wiki/Truth
While this entry sheds light on some aspects of the topic, the text is rather unbalanced and not very deep. The essence of Tarski's "semantic conception of truth" seems to be lost and the "epistemic conception of the truth" is being turned into a "consensus theory" strawman.
It seems to me that the author engages in a lot of wordplay to sidestep the issue of the exact nature of the "correspondence" between truth and the facts, which does not help make understood the linguistic/semantic nature of truth. In doing so, he treats "truth" as something preexisting and equivalent to "the facts", which does not help make understood the "coherence theory" of truth either.
Part of the problem is that the distinction between truths within a formal system vs truths about the real world is not made clear. Here are some more wikipedia entries which I found interesting:
www.wikipedia.org/wiki/Philosophy_of_language
<begin quote>
The philosophy of language is the study of philosophical questions about language, especially about meaning and truth (of words, phrases, and sentences) in general.
I say "in general" at the end of the definition because the philosophy of language doesn't ask what particular words mean, or whether particular sentences are true. (Except of course for words and sentences about the language.) Rather, it asks what meaning and truth in general are. What are the meanings of the words "meaning" and "truth"? How are we to understand these concepts?
<end quote>
www.wikipedia.org/wiki/Logic
<begin quote>
There are a variety of ways one can construct systems of logic, and a variety of things one might call "logic." With the caveat that this is not the only way to theorize it, the following is the most straightforward account the various characteristic features of logic. A system of logic (or a given "logical language" or "formal language" simply "a logic") will generally consist of the following:
(1) a vocabulary and a grammar. This might be the vocabulary and grammar of ordinary language, or it might be a set of individual letters representing sentences with specific symbols ("&", "v") for connecting them; or it might be more elaborate still, with constants, predicates, variables, and quantifiers. In any case, this part must specify which symbols, and which strings of symbols, count as part of the logic in question.
(2) Semantics. In ordinary linguistics, semantics is the study of meaning. In logic, semantics consists of something narrower but similar: providing "interpretations" the parts of the language. (Giving an interpretation might in osme cases just be giving a meaning; but generally a more rigorous definition of "interpretation" is expected than is availablein the case of "meaning.") The idea is that now that you have a language, you have to decide what it says. For example, in a simple sentential logic, a semantics will typically provide all of the atomic sentences with a "truth-value" (T of F), and explain each of the connectives ("and", "or", "not") in terms of how the truth-values of its "output" sentences are related to the truth-values of its "input" sentences. This is often done using "truth tables," a device invented by Wittgenstein. The point of a semantics is normally to explain each sentence and determine which of them are "logical truths," which "logical contradictions," and how sentences are interrelated in a variety of ways (mutual consistency, interchangeability, implication). Semantics does not have to do just this; see (4), below.
(3) Proof Theory. A proof theory is a method of actually inferring, deriving, sentences from one another. That is, you now have a language, and you have decided what its various individual sentences mean: now, how are you to go about deciding which ones are true and which ones are false--that is, reasoniong from one to another. For example, a typical proof theory for sentetial logic will provide a method for introducing each of its logical connectives, and a method for eliminating them. (Suppose you have a symbol like this "-->" (Grammar), and you interpret "A-->B" as "If A then B" (Semantics). Then your Proof Theory might tell you that whenever you have "A" and you also have "A-->B", you may write down "B".) The general picture is that now that you have a language, with meanings, you are given a set of rules for moving from one sentence to another.
(4) Applications. What do you want to do with your logic?
In a sense only grammar and vocabulary are necessary. Many different systems of logic have been devised. Some are simply theoretical studies, with no applications. Furthermore there are a variety of ways in which proof theory can be made identical to semantics, ("Derive any sentence that is sementically valid") or vice versa, ("Everything your proof-theory tells you is true"). Some logics reflect the way (sane, intelligent) people actually reason; others explicitly do not. It is widely but not universally assumed among philosophers that the bulk of "normal" proper reasoning can be captured by first-order predicate logic, if one can find the right method for translating ordinary language into that logic.
<end quote>
and last but not least
www.wikipedia.org/wiki/Naive_relativism_about_truth
Also, here is a Tarski's classic (1944):
The Semantic Conception of Truth
and the Foundations of Semantics
http://www.ditext.com/tarski/tarski.html
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