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Notes Dictated to G.E. Moore in Norway: Difference between revisions
Notes Dictated to G.E. Moore in Norway (view source)
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This is the actual procedure of [the] ''old'' Logic: it gives so-called primitive propositions; so-called rules of deduction; and then says that what you get by applying the rules to the propositions is a ''logical'' proposition that you have ''proved.'' The truth is, it tells you something ''about'' the kind of propositions you have got, viz. that it can be derived from the first symbols by these rules of combination (= is a tautology). | This is the actual procedure of [the] ''old'' Logic: it gives so-called primitive propositions; so-called rules of deduction; and then says that what you get by applying the rules to the propositions is a ''logical'' proposition that you have ''proved.'' The truth is, it tells you something ''about'' the kind of propositions you have got, viz. that it can be derived from the first symbols by these rules of combination (= is a tautology). | ||
Therefore, if we say one ''logical'' proposition ''follows'' logically from another, this means something quite different from saying that a ''real'' proposition follows logically from ''another.'' For so-called ''proof'' of a logical proposition does not prove its '' | Therefore, if we say one ''logical'' proposition ''follows'' logically from another, this means something quite different from saying that a ''real'' proposition follows logically from ''another.'' For so-called ''proof'' of a logical proposition does not prove its ''truth'' (logical propositions are neither true nor false) but proves ''that'' it is a logical proposition (= is a tautology). <!--[''Cf''. 6.1263.]--> | ||
Logical propositions ''are forms of proof:'' they shew that one or more propositions ''follow'' from one (or more). <!--[''Cf''. 6.1264.]--> | Logical propositions ''are forms of proof:'' they shew that one or more propositions ''follow'' from one (or more). <!--[''Cf''. 6.1264.]--> | ||
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It only remains to fix the method of comparison by saying ''what'' about our simples is to ''say'' what about reality. E.g., suppose we take two lines of unequal length: and say that the fact that the shorter is of the length it is is to mean that the longer is of the length ''it'' is. We should then have established a convention as to the meaning of the shorter, of the sort we are now to give. | It only remains to fix the method of comparison by saying ''what'' about our simples is to ''say'' what about reality. E.g., suppose we take two lines of unequal length: and say that the fact that the shorter is of the length it is is to mean that the longer is of the length ''it'' is. We should then have established a convention as to the meaning of the shorter, of the sort we are now to give. | ||
From this it results that "true" and "false" are not accidental properties of a proposition, such that, when it has meaning, we can say it is also true or false: on the contrary, to have meaning '' | From this it results that "true" and "false" are not accidental properties of a proposition, such that, when it has meaning, we can say it is also true or false: on the contrary, to have meaning ''means'' to be true or false: the being true or false actually constitutes the relation of the proposition to reality, which we mean by saying that it has meaning (''Sinn'')''.'' | ||
There seems at first sight to be a certain ambiguity in what is meant by saying that a proposition is "true", owing to the fact that it seems as if, in the case of different propositions, the way in which they correspond to the facts to which they correspond is quite different. But what is really common to all cases is that they must have ''the general form of a proposition.'' In giving the general form of a proposition you are explaining what kind of ways of putting together the symbols of things and relations will correspond to (be analogous to) the things having those relations in reality. In doing thus you are saying what is meant by saying that a proposition is true; and you must do it once for all. To say "This proposition ''has sense''" | There seems at first sight to be a certain ambiguity in what is meant by saying that a proposition is "true", owing to the fact that it seems as if, in the case of different propositions, the way in which they correspond to the facts to which they correspond is quite different. But what is really common to all cases is that they must have ''the general form of a proposition.'' In giving the general form of a proposition you are explaining what kind of ways of putting together the symbols of things and relations will correspond to (be analogous to) the things having those relations in reality. In doing thus you are saying what is meant by saying that a proposition is true; and you must do it once for all. To say "This proposition ''has sense''" means '"This proposition is true" means ... .' ("p" is true = "p" . p. Def. : only instead of "p" we must here introduce the general form of a proposition.)<!--<ref>The reader should remember that according to Wittgenstein '"p"' is not a name but a description of the fact constituting the proposition. See above, p. 109. [''Edd''.]</ref>--> | ||
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In settling that it is to be interpreted as a tautology and not as a contradiction, I am not assigning a ''meaning'' to a and b; i.e. saying that they symbolize different things but in the same way. What I am doing is to say that the way in which the a-pole is connected with the whole symbol symbolizes in a ''different way'' from that in which it would symbolize if the symbol were interpreted as a contradiction. And I add the scratches a and b merely in order to shew in which ways the connexion is symbolizing, so that it may be evident that wherever the same scratch occurs in the corresponding place in another symbol, there also the connexion is symbolizing in the same way. | In settling that it is to be interpreted as a tautology and not as a contradiction, I am not assigning a ''meaning'' to a and b; i.e. saying that they symbolize different things but in the same way. What I am doing is to say that the way in which the a-pole is connected with the whole symbol symbolizes in a ''different way'' from that in which it would symbolize if the symbol were interpreted as a contradiction. And I add the scratches a and b merely in order to shew in which ways the connexion is symbolizing, so that it may be evident that wherever the same scratch occurs in the corresponding place in another symbol, there also the connexion is symbolizing in the same way. | ||
We could, of course, symbolize any ab-function without using two ''outside'' poles at all, merely, e.g., omitting the b-pole; and here what would symbolize would be that the three pairs of inside poles of the propositions were connected in a certain way with the a-pole, while the other pair was ''not'' connected with it. And thus the difference between the scratches a and b, where we do use them, merely shews that it is a different state of things that is symbolizing in the one case and the other: in the one case that certain inside poles '' | We could, of course, symbolize any ab-function without using two ''outside'' poles at all, merely, e.g., omitting the b-pole; and here what would symbolize would be that the three pairs of inside poles of the propositions were connected in a certain way with the a-pole, while the other pair was ''not'' connected with it. And thus the difference between the scratches a and b, where we do use them, merely shews that it is a different state of things that is symbolizing in the one case and the other: in the one case that certain inside poles ''are'' connected in a certain way with an outside pole, in the other ''that'' they are ''not.'' | ||
The symbol for a tautology, in whatever form we put it, e.g., whether by omitting the a-pole or by omitting the b, would always be capable of being used as the symbol for a contradiction; only not in the same language. | The symbol for a tautology, in whatever form we put it, e.g., whether by omitting the a-pole or by omitting the b, would always be capable of being used as the symbol for a contradiction; only not in the same language. | ||