The Jugendbewegung and Its Effect on Carnap’s Weltanschauung
In an interview (Haller and Rutte 1977, 27-28), Heinrich Neider, a former member of the Circle, remembered Carnap as follows:
[Carnap] was then [around World War I] an independent social democrat [...], Carnap was never a communist. But he was nevertheless a radical socialist, even if it was not something you would have guessed when you saw him. He was a man unable of any outburst of affect,  
from whom I have never heard an impolite or despising word and to whom any kind of fanaticism was alien. I considered him which such a reaction of incredulity, when he said:
‘I, who was an independent at that time’, and I said: ‘I would absolutely not believe that of you’ and he answered to that by the following reflection: ‘There are many things you would not believe about me, I have also been there at the Hohe Meifiner festival’.
The “Hohe Meihner” is a mountain in Hesse, Germany, where Germans planned to celebrate the Battle of Leipzig against Napoleon. 1913 was the centenary and they organized a huge national-military-patriotic festival. On the 11th and 12th of October, 1913 the members of the GYM planned a huge counter-festival, with 4000 participants from all over the country; different groups of the Movement were gathering at the top of the mountain. One enthusiastic member and actually organizer of the counter-festival was Carnap.
The GYM, whose first group was called the Wandervogel [birds of passage], began at the end of the nineteenth century in Berlin: it was a “large-scale rebellion of well-off adolescents against the perceived conformism of their parents and teachers to the rigid norms of the society into which students were being socialized” (Carus 2007a, 50). The main roots of the GYM could be found in German Romanticism but members of the GYM tried to revive some customs and habits also from medieval times: they arranged extensive and long ramblings in the countryside, where they eat what they find and could make from the elements of nature. They tried to get closer to the peasantry and master their lifestyle with all its naivete and purity.
The latter characteristics were of the utmost importance for the participants. Members of the GYM abstained from the “bourgeois” vices and drugs, such as coffee, tobacco, alcohol. As Quine (1971, xxiv) recalled later: “Carnap’s habits were already austere: no science after dinner, on pain of a sleepless night. No alcohol ever. No coffee.” So instead of the usual contemporary lifestyle or traditions from the city, these young people created their own habits and culture: they sang while the walked, slept under the open sky, danced and read poems.
Carnap was a member of the GYM’s local group in Jena, called Serakreis [Sera Circle]; it was organized by the famous publisher Eugen Diederichs. Actually, Carnap was present at the Hohe MeiBner as one of the representatives and for some time leader of the Serakreis. He remembered the gatherings of the circle, especially its Festival of the Midsummer night as follows:
Influenced by Skandinavian customs, there were songs, dances, and plays. Diederichs read the Hymn to the Sun by St. Francis of Assisi, after sundown the big fire was lighted, encircled by the large chain of singing boys and girls, and when the fire had burned down there came the jumping of the couples through the flames. Finally, when the large crows of guests had left, our own Circle remained at rest around the glowing embers, listening to a song or talking softly, until we fell asleep in the quiet night under the starry sky. (Carnap, 1957, [UCLA], Box 2, CM3, MA-5, p. B30.)
The aim of the movements was “to find a way of life which was genuine, sincere, and honest, in contrast to the fakes and frauds of traditional bourgeois life; a life, guided by the own conscience and the own standards of responsibility and not by the obsolete norms of tradition.” Though Carnap complained a lot about his mem- ory and the autobiography is indeed inaccurate and sloppy at some points, his recollection about the GYM agrees with the original documentation of the movement: “Free German Youth desires, of its own determination and under its own responsibility, to shape its life with inner authenticity [Wahrhaftigkeit]. It stands united for this inner freedom under all circumstances” (Messer 1924, 19-20).
It would be hard to overestimate the influence of the GYM on Carnap’s thought. In the unedited and unpublished intellectual autobiography, he even devoted a section to these ideas, entitled as “Weltanschauung: Religion, enlightenment, youth movement” (B18). What he learned and acquired there is not a set of theoretical statements and doctrines, but a way and attitude towards life [Lebensgefuhl], a form of life [Lebensform] and a certain worldview [Weltanschauung]. One could say with Dilthey (1968, 86) that worldviews are not the “products of thought.” A worldview is, after all, such an a-logical, non-conceptual and non-structured totality of feelings and experiences which underline all the products of the human mind [Geist]. From such a viewpoint, “theoretical philosophy is neither the creator nor the principal vehicle of the Weltanschauung of an epoch; in reality, it is merely only one of the channels through which a global factor - to be conceived as transcending the various cultural fields, its emanations - manifests itself’ (Mannheim 1921- 22/1959, 38). Philosophical contents, considered as cultural products and philosophical styles, are just expressions and documentations of worldviews.
Since worldviews are pre-propositional, they are evidently having a nontheoretical character; but they are not irrational if we mean by the concept something meaningless. Worldviews are rather a-theoretical (and/or a-rational) complexes of feelings and experiences, hence rational justification is not required in their case: worldviews do not violate the rules and norms of rationality since they serve as the hidden, but the continuous base of rationality and theoretical argumentation.11
Though Carnap is evidently not referring to what has been said earlier, one could still interpret his words as claiming that the suitable cultural medium and social experiences could influence philosophy itself in a fruitful manner, which is, as Mannheim (1921-22/1959, 38) said, “merely one of [the] manifestations [of worldviews] and not the only one”:
For those whose work is on a purely theoretical nature, there is the danger of a too narrow concentration on the intellectual side of life, so that the properly human side may be neglected. I think it was very fortunate for my personal development during these decisive years that I could participate both in Freiburg and in Jena in the common life of such fine and inspired groups of the Youth Movement. (Carnap, 1957, [UCLA], Box 2, CM3, MA-5, p. B32.)
Though Carnap participated in the GYM only between 1910 and 1914, he actively maintained his relation to his fellows during and after the First World War.  He continuously corresponded with the members, read their pamphlets and articles which were published in their journals. His friendships made in the movement turned out to be lasting for decades and in some cases, they were life-long relations. Carnap got to know the German sociologist Hans Freyer in the GYM, and Freyer’s ideas about the Geisteswissenschaften became very influential on the Aufbau and Freyer played an important role in transmitting the philosophy of Wilhelm Dilthey in the formative years of Carnap. After the First World War, Carnap organized a workshop in Buchenbach about the “system of sciences”: the participants were his closest friends from the Serakreis, namely Freyer, the pedagogic Wilhelm Flitner, and the art historian and photographer Franz Roh. The discussion group of Carnap, Freyer, Roh and Flitner in the summer of 1920 had a well-documented effect on the Aufbau and on the early thoughts of Carnap.
All these friends shared the same experiences in the GYM and the movement’s impact remained quite detectable and fundamentally important for Carnap:
[...] the spirit that lived in this movement, which was like a religion without dogmas, remained a precious inheritance for everyone who had the good luck to take an active part in it. What remained was more than a mere reminiscence of an enjoyable time; it was rather an indestructible living strength which forever would influence one’s reactions to all practical problems of life. (Carnap, 1957, [UCLA], Box 2, CM3, MA-5, p. B34-B35.)
What Carnap learned is a certain attitude: we should not accept blindly any doctrine, knowledge and the heritage of our ancestors and other authorities just as it stand. We have the right and ability to revise everything, to reshape and rebuild (Aufbau) our material, cultural and social environment and to question every convention and arrange our cultural world as we wish. We have a total freedom [vollige freiheit] in these questions. Carnap formulated these ideas in his published autobiography under the label of “scientific humanism”:
[.] man has no supernatural protectors or enemies and that therefore whatever can be done to improve life is the task of man himself. [.] we had the conviction that mankind is able to change the conditions of life in such a way that many of the sufferings of today may be avoided and that the external and the internal situation of life for the individual, the community, and finally for humanity will be essentially improved. (Carnap 1963, 83)
In his unpublished autobiography, actually, he told a story about a conversation with a peasant in a remote village of the Black Forest after the First World War which documents the above-mentioned trends:
We looked at an airplane at great distance, high in the sky, and he said: ‘They say that sometimes people fly in such machines. But that is not possible.’ I told him that I had flown a few times in an airplane. He looked at me somewhat suspiciously, shook his head, and said: ‘Now look here: I am much older than you; I know very well what can be done and what cannot. Now you believe me, this thing is just not possible.’ (Carnap 1957, [UCLA], Box 2, CM3, MA-4, pp. N17-N18.)
This example shows quite well that attitude against which Carnap and his youth friends stood up.
I would like to end this section with the mentioning of the examples where one can evidently find the effect of the GYM on Carnap’s thought. First there is the notorious principle of tolerance (Carnap 1934/1937, §17), which says, after all, that one is totally free to choose between logical systems and (philosophical/scientific) languages as he wishes (though the principle was extendable for methods also). Engineer your schemes and conceptions as you wish, decide which one fits your space of (practical and theoretical) reasons the best and leave behind the authoritative a priori/armchair-style philosophical reasoning.
The second point (which is actually connected to the first) is that our freedom is extended also to the practical realm through the dialectical conception of explication (Carus 2007a): since the possible consequences of the various possible acts affect our practices and these consequences are codified in different language forms, our actions and practical decisions are not fixed but relative in a sense to a particular language form. This conception was formulated compactly by Richard Jeffrey
(1994, 847) who was a close collaborator of Carnap on the theories of probability and inductive logic in the last few decades of his life:
Philosophically, Carnap was a social democrat; his ideals were those of the enlightenment.
His persistent, central idea was: »It’s high time we took charge of our own mental lives«, time to engineer our own conceptual scheme (language, theories) as best we can to serve our own purposes; [...] time to accept the fact that there’s nobody out there but us, to choose our purposes and concepts to serve those purposes, if indeed we are to choose those things and not simply suffer them. [.] For Carnap, deliberate choice of the syntax and semantics of our language was more than a possibility it was a duty we owe ourselves as a corollary of freedom.
If the GYM had such a detectable and important influence on Carnap’s intellectual development as claimed here, then one could rightly ask that why did he cut it from his intellectual autobiography? I will try to indicate some possible reasons in the next section.