Two chief problems of the theory of knowledge are the question of meaning and the question of verification. The first question asks under what conditions a sentence has meaning, in the sense of cognitive, factual meaning. The second one asks how we get to know something, how we can find out whether a given sentence is true or false. The second question presupposes the first one. Obviously we must understand a sentence, i.e. we must know its meaning, before we can (...) try to find out whether it is true or not. But, from the point of view of empiricism, there is a still closer connection between the two problems. In a certain sense, there is only one answer to the two questions. If we knew what it would be for a given sentence to be found true then we would know what its meaning is. And if for two sentences the conditions under which we would have to take them as true are the same, then they have the same meaning. Thus the meaning of a sentence is in a certain sense identical with the way we determine its truth or falsehood; and a sentence has meaning only if such a determination is possible. (shrink)

Two chief problems of the theory of knowledge are the question of meaning and the question of verification. The first question asks under what conditions a sentence has meaning, in the sense of cognitive, factual meaning. The second one asks how we get to know something, how we can find out whether a given sentence is true or false. The second question presupposes the first one. Obviously we must understand a sentence, i.e. we must know its meaning, before we can (...) try to find out whether it is true or not. But, from the point of view of empiricism, there is a still closer connection between the two problems. In a certain sense, there is only one answer to the two questions. If we knew what it would be for a given sentence to be found true then we would know what its meaning is. And if for two sentences the conditions under which we would have to take them as true are the same, then they have the same meaning. Thus the meaning of a sentence is in a certain sense identical with the way we determine its truth or falsehood; and a sentence has meaning only if such a determination is possible. (shrink)

In 1954 Hempel wrote “Once the idea of a partial specification of meaning is granted, it appears unnecessarily restrictive, however, to limit the sentences effecting such partial interpretation to reduction sentences in Carnap's sense. … Generally, then, a set of one or more theoretical terms, t1, t2 ⃛, tn, might be introduced by any set M of sentences such that M contains no extralogical terms other than t1, t2 ⃛, tn, and observation terms, M is logically consistent, and M is (...) not equivalent to a truth of formal logic. The last two of these conditions serve merely to exclude trivial extreme cases. A set M of this kind will be referred to briefly as an interpretative system, its elements as interpretative sentences.” This is the last move in a process in which the idea of definition has been widened beyond the explicit or equivalence definition which was the basis of earlier thought on the subject of introducing new words into a language. It would seem that the scheme proposed by Hempel must represent the final move, for it would seem difficult to conceive any more liberal description of a purely direct and verbal scheme. Among the predecessors of Hempel in this liberalising movement I will mention Ramsey and Braithwaite whose views stem ultimately from Campbell, and are based on the idea that the “interpretative system” is essentially a scientific theory, and Carnap who introduced the particular notion of a “reduction sentence”, and who was more directly the source of Hempel's own ideas. (shrink)