Thursday, March 29, 2007

3.317 Fixing the values of a propositional variable is specifying the propositions whose common characteristic the variable is.

The fixing is a description of these propositions.

The fixing will therefore deal only with symbols, not with their meaning.

And the only thing essential to the fixing is that it is only a description of symbols and tells nothing of the symbolized.

How the description of the propositions occurs is unessential.

Black (p. 129) says that ‘signs,’ here and in 3.33, would be better for Symbolen than ‘symbols.’

Me: Saying that X = 2 or -2 tells us that any proposition containing 2 or -2 (which the proposition “201 – 23 = 178” does not) has the variable X in common. A statement such as “X = 2” does not tell us the meaning of X. This might be easier to see with a statement of the same form in which we do not already know the meanings of the words, e.g. “A boojum is a snark.” This does not tell you what a boojum is. It simply tells you that the signs “boojum” and “snark” can be used interchangeably. (This might not be true in fact, at least in all cases. The expressions “that evil tyrant” and “your worshipful majesty” might refer to the same man, but this does not make them interchangeable exactly. Still, to whom you were referring would probably be clear enough were you to make the mistake of mixing these expressions up.) Attempts to clarify language by means of logical analysis seem likely to tell us nothing at all about the world, therefore.

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