Rudolf Carnap

1891-1970 · German-American · Philosophy of Science, Philosophy of Language, Logic, Empiricism

In logic, there are no morals.

Rudolf Carnap arrived in Vienna already shaped by one encounter: Gottlob Frege's lectures at Jena, which convinced him that mathematical logic was philosophy's sharpest tool. There he joined a circle — Schlick, Neurath, Gödel among them — intent on clearing philosophy of metaphysical fog and placing knowledge on empirical and logical foundations.

Topics Rudolf Carnap addresses

• the constitution system
• the principle of tolerance
• logical syntax of language
• the elimination of metaphysics
• the verifiability principle
• internal vs external questions
• the analytic/synthetic distinction
• testability and meaning
• protocol sentences
• quasi-analysis
• meaning postulates
• intension and extension
• explication
• degree of confirmation
• inductive logic
• the continuum of inductive methods
• L-truth
• semantics vs syntax
• pseudo-problems in philosophy
• linguistic frameworks
• the unity of science
• physicalism
• rational reconstruction
• confirmation theory

Questions to put to Rudolf Carnap

The Constitution System and the Aufbau

• What were you actually trying to do in the Aufbau?
• Why did you choose an autopsychological basis for the constitution system?
• How does quasi-analysis work in building up the structure of concepts?
• Is the Aufbau a phenomenalist reduction to sense data?
• What makes a philosophical problem a pseudo-problem?

The Elimination of Metaphysics

• What's wrong with Heidegger's claim that 'the Nothing noths'?
• How can a grammatically correct sentence be meaningless?
• What's the difference between metaphysics and lyrical poetry?
• What happened at Davos in 1929 that shaped your view of metaphysics?
• Did you soften or deepen your attack on metaphysics in 'Testability and Meaning'?

Logical Syntax and the Principle of Tolerance

• What do you mean by 'In logic, there are no morals'?
• How can there be multiple correct logics?
• What's the difference between a syntactical rule and a philosophical argument?
• Are classical logic and intuitionist logic really just different proposals?
• What makes a language framework better or worse for scientific work?

Semantics and the Internal/External Distinction

• What's the difference between an internal and an external question?
• How do you decide whether to adopt a language framework?
• What's at stake in the dispute between realism and anti-realism about abstract objects?
• How do meaning postulates determine what's analytic in a language?
• What's the difference between intension and extension?

The Carnap-Quine Debate

• Does the analytic/synthetic distinction survive Quine's attack in 'Two Dogmas'?
• Why does Quine think there's no clear boundary between analytic and synthetic truths?
• Is analyticity supposed to work in natural language or only in constructed frameworks?
• How do you respond to Quine's holism about confirmation?
• What did Quine misunderstand about your actual position?

Inductive Logic and Confirmation

• How can probability be logically definable rather than subjective?
• What's a c-function and how does it measure degree of confirmation?
• Why isn't inductive logic just a matter of personal degrees of belief?
• How does your view differ from the subjective Bayesian tradition?
• What's the continuum of inductive methods?

Converse with Rudolf Carnap on Simposeum. Replies are grounded in Rudolf Carnap's own writing, cited to the page.