Logical Positivism

Ernst Mach and Heinrich Hertz had considered that we were constructing models of the world and that our entire knowledge was in that sense constructed — nothing but interpretations of data.

Gottlob Frege, Bertrand Russel and eventually Ludwig Wittgenstein led positivism into a new era – the era of the linguistic turn – by focusing on the statements which we have to make wherever we are concerned with “facts” and wherever we construct models that refer to facts.

The language of logic became important here. A statement of a fact is of scientific value as soon as we can think of a verification or a falsification, of research to substantiate or dismiss this statement. What you have stated can turn out to be “the case” – as in a “positive” medical test result in which anti-bodies were detected, or it can turn out to be “not the case” as in a negative test result, when you show no signs of the infection.

The area of statements that “make sense” in a research project is apparently wide. “Earth has got two moons” is a statement that makes sense in a scientific exploration, even though we have already noted that this is not the case. We can easily discuss the requirements of a meaningful statement (meanigful in the sciences) and we can already state that those statements that turn out to be positively true are a logical subset of all the imaginable statements of things as they could perhaps be.

The statement about the two moons orbiting Earth makes sense, because we have an idea of what situation we should have if we were to conclude: yes this is the case. (Some planets actually do have more than one moon, as we have found out.) A scientific statement is connected to a notion of the situation in which we would verify or falsify the assertion.

Can we gather all our knowledge about the world in factual statements? – Wittgenstein asked in his ground breaking Tractatus (1922). And: What are the limits of this our knowledge if we can?

Both questions are the two crucial positivistic questions which Comte had already asked it in his Dicours sur l’esprit positif (1844), §13. Positivists are concerned with the limitations of their statements and of scientific research in general; and they try not to stretch their statements into metaphysical speculative spheres.

The first question – can we use fact statements with the aim to give a picture of the world as far as we experience it? – received a positive answer in Wittgenstein’s Tractatus: Whatever we note about the world or a more specific object of our research, we will be able to cope with it in factual statements. Any kind of scientific representation of the world is reducible to fact statements. If I identify an object up to the point that I can tell it apart from another similar object, then this is because I can make factual statements of these distinctive specificities. Translated into a banal situation at the laundry, I will say “This actually is my jacket, I can identify it because it has this little flaw, which I remember”. I can make photographs of the specific aspects to make the identification easier, yet the images will again only make sense because I will be able to translate the into statements of facts: “you see on this picture this specific detail which you find only in this objet none of the others on this table…”

Whatever I know as special of the world can be put into statements of aspects I use to identify it. There are, however statements that are not verifiable in the same sense: “Thou shalt not kill” is a statement of quite another class. I may say: “It is a fact that this is a Biblical command, the statement is found in Exodus 20:13”, but how do I prove that it is a fact of the world I am experiencing? What would the world look like if the statement was true? What would it look like if it were false? The statement is non-descriptive, on another level, voluntary one might say.


Causality is another point of interest here. I can claim: “an object topples as soon as its centre of gravity is no longer above its basis”. I could alternatively claim: “an object topples because its centre of gravity is no longer above its basis”. Statement two introduces a new force, the force of causality, into the sphere of statements, but what is the test with which I can determine that statement two is needed and that statement one will not do the job in a description of things as we experience them, or in a grognosis of events? If we restrict our sciences to entities we need in order to describe things and to foretell events we will do without causality, so Wittgenstein in a new consideration of what David Hume had already considererd and what Comte had reaffirmed.

Ludwig Wittgenstein’s considerations were in the 1920s embedded in a move of debates promoted by groups such as the Vienna Circle with Rudolf Carnap, Kurt Gödel, Hans Hahn, Otto Neurath. The second wave of considerations that dealt basically with language and the questions how we link our statements to the world inspired linguists and philosophers in the greater movement of the linguistic turn that led toward structuralism and post-structuralism as large interdisciplinary movements of thought.

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