Logical Positivists: Ayer and Foundations of Knowing"

Logical positivists are philosophers who are concerned with meaning and various criteria for verifying truth statements. According to logical positivists like Ayer, in order to possess meaning, statements must adhere to our experience of the world, there must be certain principles inherent in true and false statements which create some kind of method of verification, and finally, there must be a clear understanding as to any verification in principle and in practice. A problem arose since properties like truth could not be given intrinsically. Positivists understood that unlike scientific proofs, a difficulty existed in how to link language statements with reality when discussing philosophical statements. Also they did not want to alienate objective fact from metaphysical statements, since they too can contain meaning and merit.

Ayer's criterion was that a statement is directly verifiable if it is either itself an observation statement or is such in conjunction with one or more observation-statements which are not deducible from the premises alone. Logical positivists believed that they could perform logical analyses of statements which could explicitly reveal whether the statements possessed verifiable meaning. For example, "Are there numbers?" The fact that numbers exist is not factual, but conceptual. "There is no empirically or formally discoverable fact of the matter that determines their truth-value." By deduction, the logical positivists accept the "linguistic framework" within which claims can be made about the truth or falsity of statements.

The fate inherent in assigning values to linguistic statements is dire when we consider the problem of assigning criterion of verifiability for metaphysical, moral or aesthetic statements. First, we may be making presumptions about existence. In our example above regarding numbers, we can only understand such existence or reality in relation to the objects for which the figures stand in relation, which is only what we believe them to be. John Stuart Mill pointed out that math is derived by induction from the perception of external things. Concepts are grasped by the mind, not seen by observation and therefore cannot be affirmed.

Second, it may be by custom and convention that our words have the meanings that they do. In Foundations of Knowing, Ayer asks us how we come to understand such aesthetic values as spicy, fragrant, sweet, sour and bitter. Self-presenting properties such as quantifiers and adjectives may be arrived at more by what is psychologically believed than by any certainty or evidence. It is simply, subjectively one's own opinion.

Third, there appears to be a kind of circularity which begins at any logical positivists' so-called agreed upon principles, their justification of the use of them, and how they arrived at them by induction and not deduction. For example, if scientists begin to accept abstract entities as immediate data, then such abstract interpretation of space/time points and inflationary trends in economics, can become targets of dispute because they are arrived at psychologically as well as semantically. Even if we have rules which govern what might contain meaning by inductive logic, this does not guarantee that the abstract statements are true, evident, or that they can be confirmed.