Language, Truth And Logic
The surest way to end most traditional disputes of philosophers is to establish the purpose and method of a philosophical inquiry. Language, truth and logic is a philosophical work by Alfred Jules Ayer, which brings out some of the ideas of the logical empiricists to the attention of the English-speakers. This book explains how the principle of verifiability can be applied to philosophical problems. The verification principle of logical positivism, is also referred to as the criterion of significance or criterion of meaning.
Here, analytic statements that are nessasariliy true by definition under any condition and whose validity is not tested by empirical methods are considered as tautologies. Logical and mathematical statements are tautologies where the meanings can be repeated using different words or symbols. On the other hand, empirical propositions are those which deny something about the real world and the validity is established not merely by the definition of the words or symbols they contain, but by its empirical verifiability. Only meaningful statements that are verified under certain conditions can be expressed as propositions. Strong verification is not a possibility for any empirical proposition, since the validity of the proposition depends on further experience, while, weak (probable) verification is possible for any empirical proposition. Propositions for which there are no practical means of verification may still be considered meaningful if they can be verified theoretically. Literal statements are those that can be verified either by analytical or empirical means, whereas, factual statements are meaningful without being analytic. Thus, statements that have factual meaning make assertions about the empirical world.
Philosphers criticizing this metaphysical thesis consider that philosophical statements referring to a reality transcending the limits of all possible sense experience cannot possibly have any literal significance. Kant explained that the constituted human understanding was lost in contradictions when it ventured out beyond the limits of possible experience and tried to deal with things by themselves.
We can conclude that a sentence is factually significant to any person, only if knows how to verify the proposition which it expresses. He ought to know the observations that would clearly accept or reject the proposition, under certain conditions. If the proposition is such that the assumption of its truth, or falsehood, is consistent, with any assumption, inspite of his future experience, is considered emotionally significant but not literally significant. Ayer’s logical empiricism considers philosophy as an activity of defining and clarifying the logical relationships of empirical propositions.