Logical positivism

Copyright 2016 Graham Berrisford. One of about 300 papers at http://avancier.website. Last updated 18/03/2017 19:10


Logical positivist philosophers focus on analysing the meaning of language used in philosophical propositions.


A J Ayer 1

Ludwig Wittgenstein and his seven propositions. 1

(1) The world is all that is the case. 1

(2) What is the case, the fact, is the existence of atomic facts. 1

(3) The logical picture of the facts is the thought 1

(4) The thought is the significant proposition. 1

(5) Propositions are truth-functions of elementary propositions. 1

(6) The general form of a truth-function or proposition is…... 1

(7) Whereof one cannot speak, thereof one must be silent 1

Rudolf Carnap. 1


A J Ayer

A J Ayer’s “Language Truth and Logic” contains many examples in which he analysed the language used in propositions to expose flawed reasoning.

Ludwig Wittgenstein and his seven propositions

Ludwig Wittgensteinn (1889-1951) might be the most well-known logical positivist.

His main work, the Tractatus Logico-Philosophicus, set out seven propositions.

It is a tough read, but I gather the premises are as follows.

Philosophical propositions have logical structures.

Many propositions are poorly formulated; and futile debates arise from misunderstandings.

Philosophical disagreements and confusions can be resolved by analysing the use and abuse of language.


 (1) The world is all that is the case

Wittgenstein’s first proposition includes these statements.

1 The world is all that is the case.

1.1 The world is the totality of facts, not of things.
1.2 The world divides into facts.


I understand this to say: the world is the totality of facts, and language is the totality of propositions.

The world and language are structured the same way.

Philosophy should confine itself to facts set out in well-structured propositions.


Here, we challenge the view that "facts" are the only reality.

The world is mysterious, unknowable as it is.

There are infinite ways to describe the world in terms of facts that are true enough.

Any description that helps us to predict or direct how the world moves forward must be a reasonable model of that world.

The better and more completely we can predict and direct reality, the closer our model to that reality.

(2) What is the case, the fact, is the existence of atomic facts

Wittgenstein’s second proposition includes a discussion of objects, form and substance.

2.02 Objects are simple.
2.021 Objects make up the substance of the world. That is why they cannot be composite.


Here, we say our perceptions and descriptions of reality divide it into discrete chunks.

We can divide the universe in infinite ways - into stars, planets, the eyes in a peacock’s tail, the verses of a song.

With the exception of atomic physicists, people always perceive and describe composite objects and events.

What we regard as atomic differs according to the context.

What we regard as an atomic entity differs according to the context.

What we regard as an atomic event differs according to the context.


Wittgenstein goes on to say:

2.0271 Objects are what is unalterable and substantial; their configuration is what is changing and unstable.

Here, we say "facts" are atoms of description rather than atoms of reality.

All real objects are alterable, and they have a limited life time.

Every object is created, it may change during its existence, and it will be destroyed in the end.

(3) The logical picture of the facts is the thought

Does this confuse static facts with dynamic thinking?

Here, we say a thought is a process that involves creating and using logical models.

Thinking abstracts logical models from other logical models and from physical bio-electro-chemical models.

On meeting somebody we start thinking “What is that person’s name?”

That thought process explores our physical brain and might end in our expressing a logical “fact” -  a name, right or wrong.

Or it might continue unsuccessfully, eventually fizzling out when other thoughts occupy our thinking resources.

(4) The thought is the significant proposition

Proposition 4.003 says:

“Most of the propositions and questions of philosophers arise from our failure to understand the logic of our language.”

Later: In Philosophical Investigations Sect. 90 Wittgenstein said this.

“Our investigation is a grammatical one. Such an investigation sheds light on our problem by clearing misunderstandings away.

Misunderstandings concerning the use of words, caused, among other things, by certain analogies between the forms of expression in different regions of language.”


Here, we say our language is naturally messy and imprecise.

That almost all our thoughts and propositions are fuzzy rather than true or false.

Most if not all our propositions can be true or false only with reference to others within a limited descriptive ontology.

(5) Propositions are truth-functions of elementary propositions


(6) The general form of a truth-function or proposition is…


(7) Whereof one cannot speak, thereof one must be silent

Here, we say people are well advised to ignore this rule, because natural language is not reducible to true or false sentences.

So, we need feedback to refine our thoughts and our speech.

We say what is in our minds, partly to open our thoughts to inspection and correction - by ourselves and others who listen to us.

Language based philosophy?

Here: we do not regard language as the basis for a philosophy of system theory.


“Against positivism (the position ‘There are only facts’) I would say: no, there are precisely no facts, only interpretations.

To the extent that the word ‘knowledge’ has any sense, the world is knowable: but it is interpretable differently, it has… innumerable senses, ‘perspectivism.’

It is our needs that interpret the world: our drives and their to and fro.” Nietzsch


Wittgenstein realised his “Tractacus” was self-contradictory.

In its place, he developed and entirely different linguistics.

He dropped the metaphor of language “picturing” reality and replaced it with language as a tool.


Here: natural language is a biological phenomenon, a product of evolution that gives us tools we need to communicate.

But it is imprecise, ambiguous and fluid.

The role of words in biology is to help us to remember and communicate descriptions that are true enough.

Words didn’t evolve to enable us to formulate perfectly true propositions (a concern of philosophers and mathematicians) they are not good for that.

Usually, any "state of matters" or "fact" that one animal recalls or communicates to another is a perception that has "degrees of truth".

Rudolf Carnap

Carnap has been called a logical positivist, but he disagreed with Wittgenstein.

He considered that philosophy must be committed to the primacy of science and logic, rather than verbal language.

Carnap’s second major work, Pseudoproblems in Philosophy asserted that many metaphysical philosophical questions were meaningless.

Here, we also consider that philosophy must be committed to the primacy of science and logic.


Carnap’s first major work, Logical Syntax of Language can be regarded as a response to Wittgenstein 's Tractatus.

Carnap’s Principle of Tolerance says there is no such thing as a "true" or "correct" logic or language.

His concept of logical syntax is important in formalising the storage and communication of information/descriptions.

Computers require that logical data structures are defined using a formal grammar called a regular expression.

It is said that Carnap’s ideas helped the development of natural language processing and compiler design.


the sentences of metaphysics are pseudo-sentences which on logical analysis are proved to be either empty phrases or phrases which violate the rules of syntax.

Of the so-called philosophical problems, the only questions which have any meaning are those of the logic of science.

To share this view is to substitute logical syntax for philosophy.”

— Carnap, Page 8, Logical Syntax of Language, quoted in Wikipedia.


“The purpose of logical syntax is to provide a system of concepts, a language, by the help of which the results of logical analysis will be exactly formulable.”

Philosophy is to be replaced by the logic of science – that is to say, by the logical analysis of the concepts and sentences of the sciences,

for the logic of science is nothing other than the logical syntax of the language of science.

— Carnap, Foreword, Logical Syntax of Language, quoted in Wikipedia.


Carnap defined logical syntax as:

By the logical syntax of a language, we mean the formal theory of the linguistic forms of that language – the systematic statement of the formal rules which govern it together with the development of the consequences which follow from these rules. A theory, a rule, a definition, or the like is to be called formal when no reference is made in it either to the meaning of the symbols (for examples, the words) or to the sense of the expressions (e.g. the sentences), but simply and solely to the kinds and order of the symbols from which the expressions are constructed.

— Carnap, Page 1, Logical Syntax of Language, quoted in Wikipedia.




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