# Carnap an Neurath, Santa Fe/New Mexico, 11. Mai 1943 Rudolf Carnap an Otto Neurath, 11. Mai 1943 Mai 1943

Dear Neurath‚

I suppose that in the meantimea mean time you have received my letters of January 29th and March 15th (with reply to your comments on RussellP Russell, Bertrand, 1872–1970, brit. Philosoph). About a month ago we have come back to Santa Fe; we bought a small and modest cottage high up on a hill with a wonderful view over Santa Fe and the distant mountains. It’s all very simple (only an amateur built job which manifests itself each time when it rains – it will need a few repairs to make it water-tight), but it has for us a great charm and the weather here is very pleasant, dry and sunny most of the year. Unfortunately my back does not show any “spontaneous improvement” which the Mayo people held before my eyes as a possibility. Therefore it seems probable that an operation will have to be done after all if the doctors can agree among themselves that it promises relief. Since they suggested a postponement of at least half a year probably nothing will be done before the end of August, however. I hope the operation will be successful so that I shall be able to teach in the Winter.

I hope you have received in the meantimeb mean time vol. I and perhaps already vol. II of my Semantics. Vol. II does not contain much of interest to you, I suppose, but the Preface has some bearing on the question of the usefulness of Semantics by showing the role it could and should play in the development of contemporary technical logic.

When I wrote about fellow empiricists making objections against Semantics (in the Preface of vol. I) I was, of course, thinking in the first place of you and NagelP Nagel, Ernest, 1901–1985, am. Philosoph, verh. mit Edith Nagel. I thought whether there was anything published to which I could refer. I could only think of Nagel’sP Nagel, Ernest, 1901–1985, am. Philosoph, verh. mit Edith Nagel remarks in his paper at the Harvard Congress 1939. But since these remarks were too short and that volume of the Journal has not appeared I thought it better not to refer to them. As to you, I did not remember any place where you discuss Semantics in print in any detail so that it would be possible to reply to it. I know that you often criticized the use of the concept of truth or “TRUTH” by metaphysicians or (in your Aristotelian paper) by RussellP Russell, Bertrand, 1872–1970, brit. Philosoph. But I do not remember any critical discussion of Semantics, that is to say of the concept of truth and related concepts as defined by TarskiP Tarski, Alfred, 1901–1983, poln.-am. Mathematiker und Logiker or of the semantical concepts which I later applied to empirical science in my “Foundations”. Please tell me where you discussed these things so that I may refer to it at the next occasion. 🕮

I am now working on a book about probability and degree of confirmation. I think, there I shall have to explain again the distinction between “true” and “confirmed” or “accepted”. I explained it long ago in “Wahrheit und Bewährung”; the discussion there was meant especially against you. I don’t remember that you ever tried to answer my arguments; but if you did, please tell me where. In your last letter you mention that I know sufficiently your view on degree of confirmation; but I don’t remember that we ever talked sufficiently about it. I know only the fact that you are against this concept, but I do not know your reasons. If you can explain them in a letter I shall be very much interested. For me it is clear that the concept is entirely scientific and does not have the least metaphysical component in it. Nevertheless, I too regard it as problematic but only in the sense that it is not yet clear whether we can define a quantitative or at least a topological concept of degree of confirmation which will turn out to be fruitful for scientific work. NagelP Nagel, Ernest, 1901–1985, am. Philosoph, verh. mit Edith Nagel has expressed serious doubts in his Encyclopedia-monograph.

As you can imagine, I am very sorry about the bad impression you got of my book, and that you even think it is a revival of Aristotelian metaphysics. I try to remember the many and sometimes long conversations we had in the past on Semantics. The first was in the train to Paris 1935. Then there was the public discussion at the Pre-Conference at Paris, with you and NæssP Naess@Næss, Arne, 1912–2009, norweg. Philosoph on the one side, and TarskiP Tarski, Alfred, 1901–1983, poln.-am. Mathematiker und Logiker and me on the other side. After these two discussions I remember I had the definite impression that there were no rational arguments left on your side. When TarskiP Tarski, Alfred, 1901–1983, poln.-am. Mathematiker und Logiker and I showed that your arguments were based on misconceptions concerning the semantical concept of truth you had nothing to reply. What was left, as far as we saw it, were merely your emotional reactions, namely your dislike of the term “truth” and your vague fear that this way would finally lead us back to old metaphysics. Later we sometimes had discussions on the same topic in America; but I did not have the impression that we came any step forward towards a mutual understanding, still less to an agreement. Perhaps my book will now show you more clearly what we mean by Semantics and what the nature of its concepts is, and perhaps thereby make it possible to you to be more clear and more specific in your objections. In any case, in spite of the disappointing experiences in the past, I am very willing to continue the discussions with you. I promise to you that, when we meet again, I shall very patiently listen to all objections you have and, if I find again the old misunderstandings of the semantical concept of truth, I shall try my best to explain the definition to you. I do not know whether it would be possible to make a fruitful discussion by correspondence, where the formulations are necessarily so short, while the mess of things which must be cleared up is so big. But at least we could briefly indicate to each other our views even if we cannot discuss them in detail. Certainly I should be very much interested if you could indicate to me where you believe to find the traces of Aristotelian metaphysics. One point here seems to me very important; in criticizing a concept used by an author one should not criticize the term he uses or the bad things other people have said with the same term, but the meaning which the author gives to the term, that is to say, the way he uses it, and the assertions which he makes with its help. Whether out of our correspondence or later out of conversations there will grow something that we shall regard a good 🕮{}basis for a public discussion, we shall see later.

What are your objections against Russell’sP Russell, Bertrand, 1872–1970, brit. Philosoph sign of existence? It is in general use in modern logic and I do not see how a scientific language could do without something of this kind.

The attitude of the Press concerning the Encyclopedia is very regrettable. I am enclosing a copy of my letter to them. I think the decisive word will have to come from you because the contract is between you and them.

One day, we hope in the not too distant future, we all shall sit here on our hill, look at the mountains, speak about Europe, about problems – looking with tolerance at each other, even if sometimes we have to shake our heads.

With love to you both‚

Carnap

Brief, msl., 3 Seiten, ON 222 (Dsl. RC 102-55-01); Briefkopf: msl. Santa Fe, N.M., May 11, 1943.

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