Rudolf Carnap Quotes (1891-1970)

“If someone wishes to speak in his language about a new kind of entities, he has to introduce a system of new ways of speaking, subject to new rules; we shall call this procedure the construction of a linguistic framework for the new entities in question.”

“In the summer of 1914 I attended Frege's course, Logik in der Mathematik. Here he examined critically some of the customary conceptions and formulations in mathematics. He deplored the fact that mathematicians did not even seem to aim at the construction of a unified, well-founded system of mathematics, and therefore showed a lack of interest in foundations. He pointed out a certain looseness in the customary formulation of axioms, definitions, and proofs, even in the works of the more prominent mathematicians. ...Unfortunately, his admonitions go unheeded even today.”

“If we compare. e.g. the systems of classical mathematics and of intuitionistic mathematics, we find that the first is much simpler and technically more efficient, while the second is more safe from surprising occurences, e.g. contradictions. At the present time, any estimation of the degree of safety of the system of classical mathematics, in other words, the degree of plausibility of its principles, is rather subjective. The majority of mathematicians seem to regard this degree as sufficiently high for all practical purposes and therefore prefer the application of classical mathematics to that of intuitionistic mathematics. The latter has not, so far as I know, been seriously applied in physics by anybody.”

“In the summer of 1914 I attended Frege's course, Logik in der Mathematik. Here he examined critically some of the customary conceptions and formulations in mathematics. He deplored the fact that mathematicians did not even seem to aim at the construction of a unified, well-founded system of mathematics, and therefore showed a lack of interest in foundations. He pointed out a certain looseness in the customary formulation of axioms, definitions, and proofs, even in the works of the more prominent mathematicians. As an example he quoted Weyerstrass's definition: "A number is a series of things of the same kind"... On this he commented with an impish smile: "According to this definition, a railroad train is also a number; this number may then travel from Berlin, pass through Jena... He criticized in particular the lack of attention to certain fundamental distinctions, e.g., ...between the symbol and the symbolized, ...between a logical concept and a mental image or act, and that between a function and the value of a function. Unfortunately, his admonitions go unheeded even today.”

“Our conjecture that metaphysics is a substitute, albeit an inadequate one, for art, seems to be further confirmed by the fact that the metaphysician who perhaps had artistic talent to the highest degree, viz Nietzsche, almost entirely avoided the error of that of confusion. A large part of his work has predominantly empirical content. We find there, for instance, historical analyses of specific artistic phenomena, or an historical psychological analysis of morals, In the work, however, in which he expresses most strongly that which others express through metaphysics or ethics, in Thus Spake Zarathustra, he does not choose the misleading theoretical form, but openly form of art, of poetry.”

“When I met Wittgenstein, I saw that Schlick's warnings were fully justified. But his behavior was not caused by any arrogance. In general, he was of a sympathetic temperament and very kind; but he was hypersensitive and easily irritated. Whatever he said was always interesting and stimulating and the way in which he expressed it was often fascinating. His point of view and his attitude toward people and problems, even theoretical problems, were much more similar to those of a creative artist than to those of a scientist; one might almost say, similar to those of a religious prophet or a seer. When he started to formulate his view on some specific problem, we often felt the internal struggle that occurred in him at that very moment, a struggle by which he tried to penetrate from darkness to light under an intense and painful strain, which was even visible on his most expressive face. When finally, sometimes after a prolonged arduous effort, his answers came forth, his statement stood before us like a newly created piece of art or a divine revelation. Not that he asserted his views dogmatically ... But the impression he made on us was as if insight came to him as through divine inspiration, so that we could not help feeling that any sober rational comment of analysis of it would be a profanation.”

“Yes, he is one of my heroes. I took a seminar from him under the GI bill after I got out of the Navy. It was not when I was an undergraduate. That was the only graduate course I ever took. It was on the philosophy of science, and it had a big influence on me. Later, when Carnap was giving the course in California, I persuaded him to have his wife tape record it. She typed it up and sent me the typed version. I edited it into a book called Introduction to the Philosophy of Science. That was the only popular book that Carnap ever did. All I did was edit it into language an average person could understand without knowing any math.”

“Put in a nut-shell, my thesis amounts to this. The repeated attempts made by Rudolf Carnap to show that the demarcation between science and metaphysics coincides with that between sense and nonsense have failed. The reason is that the positivistic concept of 'meaning' or 'sense' (or of verifiability, or of inductive confirmability, etc.) is inappropriate for achieving this demarcation — simply because metaphysics need not be meaningless even though it is not science. In all its variations demarcation by meaninglessness has tended to be at the same time too narrow and too wide: as against all intentions and all claims, it has tended to exclude scientific theories as meaningless, while failing to exclude even that part of metaphysics which is known as 'rational theology'.”

“It was Rudolf Carnap’s dream for the last three decades of his life to show that science proceeds by a formal syntactic method; today no one to my knowledge holds out any hope for that project.”