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Logical Positism And The Vienna Circle Essay

, Research Paper

Moritz Schlick and A.J. Ayer were both logical positivists, and members of the Vienna Circle. They had differing yet concentric views on the foundations of knowledge, and they both shared the quest for truth and certainty.

Moritz Schlick believed the all important attempts at establishing a theory of knowledge grow out of the doubt of the certainty of human knowledge. This problem originates in the wish for absolute certainty. A very important idea is the concept of “protocol statements”, which are “…statements which express the facts with absolute simplicity, without any moulding, alteration, or addition, in whose elaboration every science consists, and which precede all knowing, every judgment regarding the world.” (1) It makes no sense to speak of uncertain facts, only assertions and our knowledge can be uncertain. If we succeed therefore in expressing the raw facts in protocol statements without any contamination, these appear to be the absolutely indubitable starting points of all knowledge. They are again abandoned, but they constitute a firm basis “…to which all our cognitions owe whatever validity they may possess.” (2) Math is stated indirectly into protocol statements which are resolved into definite protocol statements which one could formulate exactly, in principle, but with tremendous effort. Knowledge in life and science in some sense begins with confirmation of facts, and the protocol statements stand at the beginning of science. In the event that protocol statements would be distinguished by definite logical properties, structure, position in the system of science, and one would be confronted with the task of actually specifying these properties. We find many expositions which seem to presuppose that through the method of protocol statements, only those assertions are understood that temporally precede the other assertions of science. This is a matter of the ultimate basis of knowledge of reality, and it is not sufficient to treat statements of “ideal constructions” (in a Platonic fashion) but one must concern oneself with real occurrences, with events that take place in time, and in which the making of judgments consists, hence with psychic acts of thought, or physical acts of speaking or writing. These acts of judgment are suitable for establishing inter-subjectively valid knowledge when translated into verbal or written expressions. Protocol statements come to be regarded as certain phrases which are not meaningful. When we retrace the path by which we arrive at all our knowledge, we always come up again the same source: sensory experiences and through the opinions of other people. On this view protocol statements would be real happenings in the world and would temporally precede the other real processes in which the production of an individual’s knowledge consists. He is not concerned who expressed the correct view, but what the correct view is. The two views, that statements register simple data of observation and stand temporally at the beginning could also be those that by virtue of their structure would have to constitute the logical starting-point of science.

A.J. Ayer seeks in his article “Verification and Experience” to determine the truth or falsehood of empirical propositions. The customary answer is that it is their agreement or disagreement with reality. He draws a distinction between “…those empirical propositions can be determined by ascertaining the truth or falsehood of other propositions, and those whose truth or falsehood can be determined directly by observation.” (3) One can test an individual proposition by establishing the truth or falsehood relating to the object of the statement. One may also deduce one universal proposition from another, and infer it by analogy, but one must arrive at a proposition for which the evidence consists solely in the truth or falsehood of certain singular propositions. No matter how many singular propositions are established, one is never entitled to regard the universal proposition as conclusively verified. Nor does the falsity of one statement negate the universal proposition. The logical asymmetry in the relationship of universal and singular propositions that has led some philosophers to adopt the possibility of falsification rather than that of verification as their criterion of empirical significance. Ayer claims philosophers have reached propositions which need not wait upon other propositions for the determination of their truth or falsehood, but are such that they can be directly confronted with the given facts. These are called basic propositions. The distinction between them and other propositions is fairly legitimate, “…then we may confine ourselves to questions concerning the nature of basic propositions and the manner in which our determination of their validity depends upon our experience.” (4) The legitimacy of the distinction between basic and other propositions is implicitly acknowledged by philosophers who reject the notion of agreement with reality as a criterion of truth. Propositions can only be compared to each other, and cannot be compared with reality or experience. There is another status of basic propositions, a class of “protocol propositions.” For a sentence to express a protocol propositions it is necessary that it should contain the name or description of an observer and some words referring to an act of observation. The claims for this form have the advantage of giving protocol propositions greater stability. One can make the truth and falsehood of any proposition whatsoever depend upon its compatibility or incompatibility with other propositions. One often does not recognize other criterion. In this respect, protocol propositions are not allowed any advantage. A protocol proposition is not one which can be directly verified by observation, for one can deny that this is possible. Other philosophers use the term “protocol” purely as a syntactical designation for a certain assemblage of words. “…One attaches such special significance to the word observation because there is no error involved in constructing sentences of a peculiar type and dignifying them with the title of Protokollsaetze, but it is arbitrary and misleading.” (5) In other words, protocol propositions are not meaningful, but they are a basis for the foundation of knowledge.

The quest for knowledge and certainty fits what we discussed with epistemology. Descartes shares the same desire for certainty in his life as do Ayer and Schlick. Kant’s reasoning that all knowledge comes into us through sensory experience applies to Schlick’s thoughts about protocol statements being ultimately determined by our experience and perception. The views of Ayer and Schlick interact heavily. The protocol proposition is similar to the idea of the protocol statement, because a statement is most often not objective nor true. Both philosophers start from the same place, which is to establish certainty in what they believe, such as Descartes did, and they arrive at the same conclusion, which is that meaningful speech is polluted with opinion and uncertainty, but that this is the way in which humans get their knowledge. Descartes discusses the ways in which people get their perceptions, ideas, and the “knowledge” they hold for true, which is through sensory experience, and this is what Ayer and Schlick say. The two differ slightly in the way that Schlick bases all statements on conforming to the protocol statement, but Ayer takes a more objective approach when he discusses the differences between basic propositions and protocol propositions. Both philosophers recognise that protocol statements are based on a structure of words which are restricted in their usage, and that they cannot communicate an idea effectively. They also both recognise that one may believe that they themselves are correct in an idea but may actually be false because they hold false perception. I believe that one may embrace a true idea, in reality, one which people cannot accept or refute because they do not know it is reality, and at the same time this person may believe a false idea. Everyone has something to contribute, but one source is not enough. I also believe that truth and falsity is a valid distinction when discussing whole truths, but that the concept of good and bad exists in reality on a scale which language often causes us to forget, and that if we could expand our vocabularies to embrace more than the “black and white” ends of this spectrum, that we would understand this concept better. This would aid epistemology because one could discern better between an idea that holds more validity over a larger picture than another, rather than assuming that by deduction, they are false and have nothing to contribute. By “lining up” the false propositions by degree, we could be better pointed toward truth. I agree with both philosophers, and with Descartes, that our perception is something we must check on and constantly analyse, because inevitably, each of us will hold some truth and some falsity.


Hanfling, Oswald, Logical Positivism (New York: Columbia University Press, 1981), p. 24-71. (I read this book and got some ideas, but no quotes)

Ayer, A.J. (editor), Logical Positivism (Illinois: Free Press, 1959), p. 209-227 (Schlick), 228-243 (Ayer).

1. Ayer, p. 210

2. Ayer, p. 212

3. Ayer, p. 229

4. Ayer, p. 231

5. Ayer, p. 232