\brief{Rudolf Carnap an W.V.O. Quine, 18. Dezember 1934}{Dezember 1934}
%\blockade{file-name hat falsches Datum, geändert in Access. Aber: Siehe Kommentar ganz am Ende}

%Prof. Dr. Rudolf Carnap

%Prag XVII

%N. Motol, Pod Homolkou

\anrede{Dear Dr. Quine,}

\haupttext{I wish to say you my best thanks for your letter of Nov.\,24 and the cable, and also for your letter of June\,29, to which
I did not answer. I am very grateful for your kind and good help, as well in the terminological questions as now in the
problem of the translator of my book\IC{\logischesyntax}. And I thank you most cordially for your book\IW{\quinebuch}. First I made a run through it and
found many interesting features, and now in the last days I studied it in detail (as a Christmas pleasure) and enjoyed
much the good structure of your system with very fine new devices and simultaneously the clarity of your explanations. My
remarks to the book\IW{\quinebuch} I am writing separately.

I am very glad that you gave three lectures about my ``Syntax''\IC{\logischesyntax} and other things, and that you had an interested
audience.

I was very surprised by your cable (please give my thanks also to Mrs. Quine\IN{\quinefrau}, Mr. Chambers\IN{\chamberstom} and Dr. Skinner\IN{\skinner}) and by your
letter about the proposal of professor Prall\IN{\prall}. I should be very glad if that proposal would be realised. Unfortunately the
decision is not mine but Ogden's\IN{\ogden}; because he made the agreement with the translator and I do not even know on what lines.
I wrote him twice, with long quotations from your letter, and I strongly recommended the proposal. Ogden\IN{\ogden} answered but
postponed the decision till after Christmas. He wrote that Countess Zeppelin\IN{\zeppelin} had sent to me some time ago the first part
of the translation. I must confess, I am in doubt whether that is true; at least I did not get anything so far. Ogden\IN{\ogden}
writes Dec.\,20: ``I was hoping to see the Countess Zeppelin\IN{\zeppelin} today, but am giving her till after Christmas before making a
decision. Her last letter said that the `Logical Syntax'\IC{\logischesyntax} would be complete in less than a month. Even if she is unable
to do it by then, there is much to be said against an American if the book\IC{\logischesyntax} is to have an English public -- in addition to
the loss of time
at so great a distance.'' That is of course nonsense, because even for the English public a Harvard\II{\harvard} professor will \neueseite{} be
more attractive than C[ountess] Z[eppelin]\IN{\zeppelin}. So it seems to me that Ogden\IN{\ogden} gives pretexts instead of his real reasons which I don't know and
which seem to be against the project. On Dec.\,22 Ogden writes that he did not yet succeed to meet C[ountess] Z[eppelin]\IN{\zeppelin}, but he had a
telegramm from her saying that the translation will be complete by January\,31. Now I wrote him again, but I am afraid
that nevertheless his decision will be in the negative. I should regret that very much especially in consideration of my
future projects. In any case say please already now to prof. Prall\IN{\prall} my most cordial thanks; there is still a chance
however little. As soon as I shall know Ogden's\IN{\ogden} decision I shall write you.

I am very grateful to you that you wrote a review\IW{} of my book\IC{\logischesyntax}. I suppose it was the first written, because the book\IC{\logischesyntax}
appeared not before July and most of reviewers take several months (sometimes even years) for writing the review.

To \uline{your questions} about ``Syntax''\IC{\logischesyntax}:

1. \uline{Definition of ``quasi-syntactical''}, p.\,178-179. You are right, an addition is here necessary. But it is
sufficient to replace ``$\grave{S}\!\grave{g}_2{}^n$'' (the accent $\grave{}$ marks Gothic letters) on p.\,178, last line, by ``ein $\grave{S}\!\grave{g}_1{}^n$ $\grave{S}\!\grave{g}_2$''. Then $\grave{S}\!\grave{g}_2$ belongs to the logical sub-language ${S}_2{}\acute{}$ of $S_2$ and is a
syntactical $\grave{S}\!\grave{g}$, because ${S}_2{}\acute{}$ is a syntactical language for $S_1$ and $\grave{Q}_1[\grave{A}_1]$ etc.
are suitable arguments for $\grave{S}\grave{g}_2$. -- It is not possible to define a \uline{logical} $\grave{S}\grave{g}_2$ in such a way that
for every $\grave{S}_1$ of $S_1$ $\grave{S}\grave{g}_2(\grave{Q}_1[\grave{S}_1])$ has the sense of ``$\grave{S}_1$ is true''; because in this case, if
we take a synthetic $\grave{S}_1$, $\grave{S}_1$ must be equipollent with $\grave{S}\grave{g}_2(\grave{Q}_1[\grave{S}_1])$ which is a logical and hence a
not-synthetic sentence, and that is impossible. -- Not every full sentence of $\grave{S}\grave{g}_2{}$ is L-determinate, but only every
f. s. having logical arguments. If we add a \uline{descriptive} description of an expression (e.g. ``the expression
written at that and that place'') as an argument to $\grave{S}\grave{g}_2{}$, then the full sentence will in general be synthetic. Thus
e.g. the quasi-syntactical sentences 1a (p.\,215) and 12a (p.\,217) are synthetic. But the \neueseite{} qu.-synt. predicate ``treats
of'' (``handelt von''), used in these sentences, is a logical one, because a full sent[ence] of this predicate with logical
arguments (logical descriptions of expressions) is L-determinate.

2. (p.\,116). You are right, the \uline{truth value of an implication sentence} can often be found in other way. But in
the special case concerned here we cannot (according to the meaning of the objection which I reject however) use a
general sentence, because the objection is based on the (erroneous) opinion that a general sentence has to be tested by
testing the single instances. -- Sometimes it is indeed sufficient to find the truth-value of one of the two parts, but
not in this case, provided we do not make use of the definition of `$P_3$'.

Many thanks also for your \uline{offprints}, which you kindly sent me. I had some doubt in respect to some points in
your ``Ontological Remarks'', but perhaps you yourself would formulate it today in a somewhat different way. Especially
interesting is your report about Whiteheads\IN{\whitehead} new approach (but hard to understand because of its shortness); is the
propositional calculus of his new system intensional like that of Lewis\IN{\lewis}?

The four weeks which we spent together in \uline{London} were a very interesting and stimulating time. I was very glad
to make the acquaintaince of Stebbing\IN{\stebbing}, Ogden\IN{\ogden}, Richards\IN{\richards}, Woodger\IN{\woodger} and others. The three lectures\IC{\londonervortraege} which I delivered at the
University are now in print; you will soon have the little book. Professor Stebbing\IN{\stebbing} seemed very satisfied with the
lectures and their effect upon the audience, and so I think that it may be a help for America also.

The terminological remarks in your former letter have been very valuable for me. I accepted your suggestions in the
terminological list for the translator (if it will be Prof. Prall\IN{\prall} I will send it to him), and I used them already, as you
will see, for the London lectures\IC{\londonervortraege}. \neueseite{}

I sent you recently an offprint ``Antinomien''\IC{\msantinomien} and some time ago a little pamphlet ``Wissenschaftslogik''\IC{\aufgabederlogik} which is
merely a popular explanation of some ideas of the last chapter in ``Syntax''\IC{\logischesyntax}. I shall send you some older offprints about
physicalism for you or others interested in these problems.

Prof. Charles W. \uline{Morris}\IN{\morris} of the University of Chicago\II{\universitychicago} was here in August for some weeks. We spoke often
together; he is very interested in constructing bridges between Pragmatism and the view of the Vienna Circle\II{\schlickzirkel} which he
considers complementary doctrines. He seems to have the serious intention to help me to come to America.

Through the help of the American Institute at Prague\II{} I am in connection with the Institute of International Education\II{\iie},
New York, asking them to organize a lecture tour through the U. S. beginning in October 1935. Perhaps that will be a
suitable way for coming in personal connection with some universities. But it would be a stretching enterprise, I
suppose. And I hope to get in some way or other an invitation for some months at one place; of course I should prefer
that to a tour of permanent travelling.

If it will not be too much loss of time, could you perhaps send back the enclosed copy with corrections? It suffices of
course to correct the serious grammatical mistakes (not expressions which are merely unsuitable). Please send me copies
of your German letters (also of the last), if you think corrections useful.

Thanks for your kind Christmas greeting. My wife\IN{\ina} and I, we send you and Naomi\IN{\quinefrau} our best greetings and wishes for the New
Year. May your work go on successfully as it started so promising; and let us hope to meet again, perhaps in the now
beginning year.}

\grussformel{Sincerely yours,\\
R. Carnap}

\ebericht{Brief, msl., 4 Seiten, \href{https://doi.org/10.48666/854826}{WQ}; Briefkopf: gestempelt \original{Prof. Dr. Rudolf Carnap \,/\, Prag XVII. \,/\, N. Motol, Pod Homolkou}, hsl. \original{18.\,Dec. 1934}.}


%[Variously Dated, Probably 1934-12-28; enclosure in previous letter)

%Prof. Dr. Rudolf Carnap

%Prag XVII

%N. Motol, Pod Homolkou

\brief{Anhang zu Rudolf Carnap an W.V.O. Quine, 18. Dezember 1934}{Dezember 1934}

\blockade{ACHTUNG: FORMELN UNVOLLSTÄNDIG, Text muss nochmal kollationiert werden}

\haupttext{\uline{Remarks about Quine's\IN{\quine} Logistic\IW{\quinebuch}.}

I find your book\IW{\quinebuch} in the whole excellent. Your system is an essential improvement of the usual system-form, and your
explanations are clear and exact. I \soutsp{have the} inten\textsp{d}\soutsp{tion} to write a review\IC{} of the book\IW{\quinebuch} for ``Erkenntnis''\II{\erkenntnis}. It was \soutsp{for me}\fnA{Die Phrase \original{for me} ist mit Pfeil markiert, der zwischen \original{pleasure} und \original{to read it} verweist. Unter dem Pfeil steht die Bemerkung \original{\textsp{better, omit ``for me'' entirely}}.} a great pleasure
to read it.

I regret that we cannot discuss some points verbally. So I shall write some remarks.

1. I should find it suitable if you had given explicitly \uline{formation rules}, i.\,e. definitions of
``sentence'', ``n-ad expression'' (esp. ``class expr.'' and ``sequence expr.'') and others (see 2, 3c), including the
expressions containing defined symbols.

2. You have a much higher degree of exactness than P. M., and there remain now only very few demands for accomplishing
exactness. So e.g. it was a lack of exactness in P. M., that no \uline{formation rules for definitions} are given but
only a practice. It will be good if you will supply that for your system. Because a reader, seeing your
practice, could perhaps think that it \replsp{were}{would be} allow\soutsp{ed}\textsp{able} to
introduce the abbreviation ``$A$'' for an expression like ``$V,x$'' (or ``$O,\alpha$'' or
others), which of course would lead to contradictions.

3. \uline{Substitution} , p.\,42. a) It seems to me very good, that you demand in your explanation of substitution the
rewriting of certain variables. That is better than my procedure (prohibiting subst. in such cases and thereby \textsp{indirectly}\fnA{Ursprüngliches \original{indirectly} ist mit Pfeil hier her verschoben, der die Randnotiz \original{\textsp{better the first time}} enthält.} compelling
\soutsp{indirectly} the rewriting before subst.)

b) I should prefer to say instead of ``written in lieu of'' (p.\,42): ``written in lieu of every free''. Then you may
leave out ``free'' in the rule; and the convention at the end of p.\,44 (containing the not quite exact expression
``construed as cases'') will be unnecessary.

c) It seems to me necessary to restrict in your rule of substitution the range of expressions allowed for substitution. \neueseite{}
You restrict it only by the condition that the result must be significant (i.\,e. must be a sentence). But that condition
is not sufficient. E.\,g. your rule allows to infer (p.\,86) $4 {symbol} 1 (x/y .\supset.\sim(z=z))$
which gives the obviously false result ``$V,y.\supset.\sim(z=z)$''.

4. p.\,51. I \textsp{do not} think we can\soutsp{not}\fnA{Der Korrektur ist die Bemerkung beigefügt: \original{\textsp{My correction here looks illogical, but it is the English idiom.}}.} treat parentheses by extra-formal
conventions, but we must give explicit rules for them (as you do in fact). There is a fundamental difference between the
use of parentheses and the use of the different sort\soutsp{e}s  of variables in your
system. The latter is in fact \soutsp{u}\textsp{i}nessential (as you say), but not the former,
because you cannot leave out the par[entheses]. Therefore I should prefer to call the parentheses primitive symbols and to take
notice of them in the formation rules (demanded above), as you did already in your informal explanations.

5. Your device of discarding \textit{descriptions} and keeping only ``$\alpha symbol x$'' defined as a sum of
classes is very fine.

6. Likewise admirable is your treatment of \uline{operators}, using ``$\hat{x}$'' as sole operator, replacing all other
sorts by combinations of ``$\hat{x}$'' with class expressions. I think this is an essential improvement. Just now I
\replsp{got}{received} a paper from Ajdukiewicz containing the question
whether such a replacement \replsp{will}{would} be possible. Now I have written him that you \textsp{have} solved this problem already. I recommended your book and
suggested \textsp{to} him \replsp{to}{that he} send you an offprint of his paper.

7. It is a great advantage of your \uline{hierarchy of types} that it includes also sentences. Hereby the desire may
arise to find a way of inclu\sout{s}\textsp{d}ing also some other symbols which now have no type (see
8.).

8. You discarded operator symbols and \uline{replaced them by class symbols}. That is a very good simplification of the
system. Perhaps we may go one step or some steps further in this direction and replace some further symbols, now
\soutsp{being} without type, by class symbols. \neueseite{}

a) There are some symbols which are now already predicates (in the \replsp{wide}{broad} sense of this word in ``General Syntax'') but are not class symbols in your system and have no type; these
are the symbols of implication, identity, equivalence, denial and conjunction. We can easily take them as class symbols,
writing e.\,g. ``$\supset,p,q$'', ``$\sim,p$'' and so on. Then the dots are discarded which in your system are
primitive symbols (and ought to be enumerated among those).

b) All defined symbols, with exception of class symbols and those just mentioned, are functors. If we keep ``\blockade{Symbol wie unten}''
(\replsp{being}{which is} the
fundamental and indispensable functor) we can replace all others by class symbols. This is possible because all
definienda of those symbols \replsp{are now already}{have become} class expressions.

\blockade{Formatierung!!}Instead of:\blockade{ZWEISPALTIG FORMATIEREN!!!} we may write:

$\ni x$

$\alpha\supset\beta\bar{a}$

$\alpha \cap\beta$

\blockade{geht noch weiter; finde ein spezielles Symbol nicht VERVOLLSTÄNDIGEN !!!!!!!!!!!!}

Then all defined symbols with sole exception of Symbol will be class symbols. In my view this will be an advantage,
because they belong then to the system of types, and we have variables for them.

c) I should prefer to replace the primitive symbols ``[]'' also by a class symbol. (The symbolised notion has\textsp{,} \replsp{in}{to} my \textsp{way of}
feeling\textsp{,} too much weight for being symbolised by punctuation \neueseite{} symbols like brackets; but that is of course only a
subjective feeling.) \replsp{There}{Here} are some possible ways:

A) We may write ``cong \blockade{symbol}'' instead of ``$[\alpha]$''. And then:

A\textsubscript{1}) either we take Symbol: as a new primitive symbol;

A\textsubscript{2}) or we take \soutsp{first} ``cong \textsuperscript{(}\blockade{???}'' \textsp{first} as \uline{one} symbol (without type); \soutsp{we define}
later on \textsp{we define} ``\textsuperscript{(}'' and show that ``cong \textsuperscript{(}'' can now be taken as a combination of that
``\textsuperscript{(}'' and a class symbol ``cong''.

B) (Perhaps preferable to A). We take ``\{symbol\}'' as \textsp{a} prim. class symbol (writing ``\{symbol\},\{symbol\},\{symbol\}'' instead
of Russell's ``\{symbol\}''). Then we may define\soutsp{, if desired,} ``cong \textsuperscript{(}\{symbol\}''\textsp{, if desired,} \replsp{by}{as} \{symbol\},  or use
only the latter (in order to avoid ``\textsuperscript{(}'' at this stage).

d) I should prefer to take ``\textsuperscript{(}'' as \textsp{a} primitive symbol. [Do you believe that it will \textsp{then} be possible to define \soutsp{then}
``cong'' (or ``\{symbol\}'')? If not, I should take both ``\textsuperscript{(}'' and ``\{symbol\}'' as pr.s.] If we take
``\textsuperscript{(}'' as pr.s., the system will contain only these 3 kinds of symbols:

1) punctuation signs: comma, inverted comma, parentheses ``( )'', \textkritik{circumflex}\fnA{Hsl.}

2) variables,

3) class constants.

\uline{All defined symbols are class constants}; hence \textsp{there} will \replsp{come}{result} a great
simplification \replsp{for}{of} the formation rules for definitions (see above 2). And the discarding of all functors, except\soutsp{ed}
``\textsuperscript{(}'', will simplify the syntactical definition \replsp{for}{of} ``class expression'' (and thereby that
\replsp{for}{of} ``sentence''), because every
class expression has the form ''\{symbol\}'' or \{symbol\} or \{symbol\}. The system of types includes every symbol with
\textsp{the} exception of the punctuation signs.

9. p. 5. We \replsp{due}{owe} the remark about the assertion sign to Wittgenstein \textkritik{p. 94}\fnA{Hsl.}, I believe.

10. p. 144, line 25. \{symbol\}.}

\grussformel{R. C.}

\ebericht{Briefbeilage, msl. Dsl., 4 Seiten, \href{https://doi.org/10.48666/853831}{RC 102-60-15 (Original WQ)}; von mehreren Kopien enthält nur die im Carnap-Nachlass liegende und mit \original{\uline{Copy}} gekennzeichnete Kopie die hier annotierten mit Rotstift eingefügten Korrekturen Quines.}
