W.V.O. Quine an Rudolf Carnap, 29. Juni 1934 Juni 1934

We are leaving Cambridge tomorrow night, for the summer. During these last days in Cambridge I have been kept extremely busy with proofs of my bookBQuine, Willard Van Orman!1934@A System of Logistic, Cambridge MA, 1934; it was desirable that I accomplish as much as possible of that work before my departure. Now, finally, I have an hour’s respite.

We shall spend the summer with my parents, at the following address:

16 Orchard Road, Akron, Ohio, U.S.A.

While there I shall finish all proof-reading and indexing of my bookBQuine, Willard Van Orman!1934@A System of Logistic, Cambridge MA, 1934, which will appear about Sept. 1 under the title A System of Logistic. Also I hope to have time for a little other writing. On Sept. 13 we shall leave on a three-weeks’ cruise to Haiti. By Oct. 5 we shall be back here in Cambridge again, at a not yet determinate address. (But I can always be reached care of Department of Philosophy, Harvard UniversityIHarvard University, Cambridge MA.)

I have arranged with the Philosophical ReviewI to reviewB your Logische SyntaxB1934@Logische Syntax der Sprache, Wien, 1934, and the editor has arranged with the Springe VerlagISpringer Verlag to send me a copy. I shall set to work at it immediately when my copy arrives. I am very eager to see the bookB1934@Logische Syntax der Sprache, Wien, 1934. 🕮

Regarding your terminological questions, I agree with your suggestions to the following extent:

1) Satz = Sentence‚

3) Gehalt = Content‚

6) Ausdruck = Expression‚

10) Ableitung = derivation‚

11) Beweis = proof‚

12) ableitbar = derivable‚

13) beweisbar = demonstrable‚

20) gültig = valid

22) determiniert = determinate‚

23) indeterminiert = indeterminate‚

25) freie, gebundeneVariable = free, bound variable.

In my book also I have used “free, bound” in preference over “real, apparent.”

Perhaps (11) and (13) seem inconsistent choices. They represent, however, commonest usage: for (a) “proof” is the more natural noun in English, and “demonstration” a laborious mot savant, whereas (b) “provable” is a tour de force, like “doable‚” “eatable‚” etc., and is hence usually avoided in favor of the purer Latin adjective “demonstrable” (just as “doable” and “eatable” are avoided in favor of “feasible” and “edible”).

Regarding (2), I should prefer

2) Folge = consequence.

“Conclusion” does not quite serve, but answers rather to “Schluß.”

As to (4), “Gehaltgleich”, I agree that a single word is desirable. This requires the introduction of a special technical word for the purpose. I suggest “equipollent‚” which according to my dictionary, had much the 🕮 desired meaning in traditional logic years ago. Etymologically also “equipollent” seems appropriate for the purpose. I heartily recommend its use.

If however you should decline this word in favor of a phrase such as “equal in content‚” I suggest that you adopt rather the phrase “alike in content.” (Even if you use “equipollent‚” this point is relevant when you come to define that word.) “Alike” is of course etymologically cognate with “gleich.” The word “equal” suggests rather likeness of quantity; “equal in content” would thus mean “having the same amount of content”. (“Equal” and “gleich” thus coincide only in the comparison of numbers, e. g., \(5 = 3 + 2\).)

As to (5), your suggestion of “universal operator” for “Alloperator” is admissible. But in my own work I have preferred to adopt “universal quantifier‚” on the basis of fairly prevalent English usage. But this is an unimportant matter; meaning is clear in either case.

As to (7), I suggest

7) Strich = accent.

It is usual in English to read \(x’\) as “x prime”, but to refer to the mark \(’\) itself as an accent (not a “prime”). As you say, “stroke” would create confusion with Sheffer’sßINSheffer, Henry Maurice, 1882–1964, am. Philosoph sign; furthermore it would not suggest the mark \(’\) to an English reader even unacquainted with Sheffer’sPSheffer, Henry Maurice, 1882–1964, am. Philosoph notion. “Dash” is impossible, for a dash is always horizontal. 🕮

Perhaps (8), then, should be construed thus:

8) Strichausdruck = accented expression.

Under (9) I advise

9) Spielraum = range‚

when the word is used in Wittgenstein’sPWittgenstein, Ludwig, 1889–1951, öst.-brit. Philosoph sense. One speaks also of the range of a variable. The word “domain” is better confined to the technical sense of Principia MathematicaBRussell, Bertrand, und Alfred North Whitehead!1910@Principia Mathematica, Cambridge UK, 1910–1913, 2. Aufl., 1925–1927 (= Bereich, or Vorbereich). Finally in the case of the Spielraum or Bereich of an operator, meaning thereby the segment of a given expression which the operator governs, the proper translation is “scope.”

For (14) I suggest

14) widerlegbar = refutable.

“Disprovable” has the shortcoming attributed earlier to “provable.”

(15) and (16) are difficult, as shown by the fact that even in English the German words “Entscheidungsproblem” and “Entscheidungsverfahren” are frequently used. Of course that procedure is undesirable. But against “decidable” and “indecidable” there are two objections:

a) “Decide” does not, like “entscheiden‚” suggest the determination of the truth or falsity of a proposition; in any case, therefore, use of the word would amount to the introduction of a special technical usage.

b) “Decidable” is an uncommon word, and grates upon the English ear because it has no French or Latin precedents “décidable”, “decidabilis”. 🕮

As one alternative I suggest

15) entscheidbar = determinable‚

16) unentscheidbar = indeterminable‚

if you do not object to thus emphasizing the parallelism with (22) and (23). Otherwise I suggest

15) entscheidbar = resoluble‚

16) unentscheidbar = irresoluble.

Very likely this last choice is best. The verb corresponding to “entscheiden” would then become “resolve”.

June 30

Our furniture, books etc. are now all packed and moved into storage. In two hours we shall be off for Ohio. I have made the sad discovery that I have packed your last letter, leaving out the next to the last by mistake. So I shall have to attempt to finish answering your terminological questions from memory.

According to my suggestion under (2), your tentative terminology “conclusion-series‚” for “Folgereihe‚” would have to become “consequence-series” instead. But doesn’t the mediaeval terminology “sorites” fit the meaning?

Similarly your “conclusion-class” or “class of conclusions”, under “Folgeklasse‚” would become “consequence-class” or “class of consequences”. But I thought you identified this with content-Gehalt. If that is the case, and the word “Folgeklasse” is used only temporarily for expository purposes leading up to that identification, then use “class of consequences” for that temporary purpose rather than “consequence-class”; the latter is more a technical word than a description, and its introduction would be 🕮 justified only by permanent use.

I believe that disposes of (17) and (18). I have forgotten what (19) was, but will send a postscript Pfeil am Rand von Autor next week covering it. Your letter is somewhere in our Ohio-bound baggage, rather than in storage.

As to (21), I think you will have to coin a word, as you suggest. But you had best make a finished job of the coinage by omitting the hyphen, thus:

21) widergültig = contravalid

I have just now remembered (19). It duplicates (2), which you had crossed out.

19) Folge = consequence.

As to (24), I suggest the following:

24) Zahlausdruck = numerical expression

Zahlzeichen = numeral

Zahlvariable = numerical variable

Please pardon the hasty and unfinished character of this letter; it is unavoidable unless the letter be delayed until we get to Ohio. Despite the haste of writing, the above conclusions have all been carefully considered; I had made all the decisions with full deliberation a day earlier than the beginning of this letter. I hope the suggestions will be of help, and am very glad that the English translation of your book is coming.

I am very grateful to you for my copy of The Unity of ScienceB1934@The Unity of Science. Übersetzung und Einleitung von Max Black, London, 1934 or Physics as a Universal LanguageB. It makes a splendid little volume, and I greatly enjoyed reading it through again in translation. On the whole I thought the translation fairly successful.

Thanks also for the reprint of your two book-🕮reviewsBB. I have not yet had a chance to read it thoroughly, so I am taking it along with me.

I am told that members of the psychology department here are becoming much interested in your writings regarding that subject.

NaomiPQuine, Naomi, 1907–1997, geb. Clayton, 1932–1947 verh. mit Willard Van Orman Quine and I are very unhappy not to be able to look forward to seeing you in America this autumn. Surely however you will have news of something in America before very long.

You ask my opinion of Malisoff’sPMalisoff, William, 1895–1947, russ.-am. Philosoph translation. I thought it rather ordinary, but not definitely bad. Meaning was clear throughout, but idiom might have been improved somewhat. I think however that there would be no harm in having him translate further articles; I noticed no serious faults in his work.

We were glad to hear of your invitation to the University of LondonIUniversität London. You will enjoy it, and it will be good training in the language. I hope your stay in London will be followed shortly by a one-way trip to America!

NaomiPQuine, Naomi, 1907–1997, geb. Clayton, 1932–1947 verh. mit Willard Van Orman Quine joins me in greetings and best wishes to you bothPCarnap, Ina (eig. Elisabeth Maria immacul[ata] Ignatia), 1904–1964, geb. Stöger, heiratete 1933 Rudolf Carnap.