Regrounding the Unworldly: Carnap’s Politically Engaged Logical Pluralism

Abstract

Recent discussions of logical pluralism trace its origins to Rudolf Carnap’s principle of tolerance; indeed, the principle is seen as one of Carnap’s lasting philosophical contributions. In this paper, I will argue that Carnap’s reasons for adopting this principle are not purely logical, but are rather founded in the Vienna Circle’s manifesto—a programmatic document that brings the Circle’s philosophical work together with a program of social change. Building on work by Uebel, Romizi, and others, I argue that we must understand the principle in light of Carnap’s role in writing the manifesto, and thus as integrated into the larger philosophical and political goals of the Circle. This history illuminates the often-ignored relationship between Carnap’s logical pluralism and his political views. Finally, I turn to the political situation of the post-World War 2 period in the United States. During this time, the Circle’s emigres in the USA transitioned their work from active efforts to reform society to the technical work that we recognize as the foundation of American analytic philosophy today. In this final section, I argue that the reasons that Carnap distanced himself from the political foundations of his view were due in large part to McCarthy-era persecution of left-wing academics.

1. Introduction

The philosophy of the Vienna Circle—variously called ‘logical positivism’ or ‘logical empiricism’—is well-known. Similarly well-known is the fact that this view, which sought to unify a commitment to empiricism with modern mathematical logic, was allied to left-wing political views.1 As Carnap puts it in his Intellectual Autobiography, “All of us in the Circle were strongly interested in social and political progress. Most of us, myself included, were socialists” ([2], p. 23). However, there is a persistent debate in the literature regarding the extent to which the content of the philosophical positions taken by members of the Circle was influenced by, or related to, their political positions.2 In this paper, I will side with those who say that the philosophical views and the political views are inextricably linked. Most work in this debate has focused on Otto Neurath and to what extent his overt political motivations are reflected in the Circle’s views in general.3 However, my focus in this paper will be on another member of the Circle: Rudolf Carnap.

Making the case that Carnap’s philosophical positions are influenced by his political outlook is not straightforward. To begin with, there are his comments that seem to push against my conclusion, for example, the very next sentences after the quotation above read: “But we liked to keep our philosophical work separated from our political aims. In our view, logic, including applied logic, the theory of knowledge, the analysis of language, and the methodology of science, are, like science itself, neutral with respect to practical aims, whether they are moral aims for the individual, or political aims for a society” ([2], p. 23). Therefore, ultimately, my task in this paper will be to explain these comments and to show that, if they are read in their proper context, they do not entail the separation between philosophical and political work that they appear to. The first two sections of the paper are devoted to establishing this context and the positive link between it and Carnap’s philosophical views. There, I will focus on Carnap’s logical pluralism as a case-study for examining his overall philosophical approach. Thus, Section 2 is an examination of Carnap’s logical pluralism focusing on his ‘principle of tolerance’ as the foundation of his pluralism; I argue in favor of a permissive reading of his principle by which there are no antecedent constraints on which logics can be proposed or adopted. Section 3 is a discussion of the context surrounding the development of this view and of the views of those that Carnap, along with the Circle more broadly, took to be their opponents. Finally, in Section 4, I return to the comments that Carnap makes that appear to militate in favor of a distinction between philosophical and political work, and the arguments that these comments should be taken at face value. I will show that, again, context is the key to understanding these comments, and once they are properly situated they do not maintain the distance between philosophy and politics that some have claimed Carnap wanted.

2. Carnap’s Pluralism: The Principle of Tolerance

This section will be focused on Carnap’s pluralism about logic, as articulated in his 1934 book The Logical Syntax of Language (hereafter: LSL). For my purposes here, a pluralist about logic is someone who thinks that there are at least two equally ‘correct’ logics, though what correctness amounts to is left unspecified; correspondingly, a monist about logic is someone who thinks that there is exactly one correct logic. I will argue (1) that Carnap is a logical pluralist, and (2) that his pluralism is quite radical. My understanding of Carnap depends on a thorough examination of his principle of tolerance, and its role in Carnap’s project in LSL, so this is where I begin.4

A question that motivates the early stages of Carnap’s work in LSL is how to resolve ongoing debates over which logic is the ‘correct’ logic to use in the foundations of mathematics, and moreover, what kinds of philosophical considerations should enter into that decision. In particular, he discusses restrictions that certain philosophers claimed needed to be in place in order to secure mathematics against paradox; in the case of Wittgenstein, whether the identity symbol should be used in logic, or in the (somewhat more complicated) case of Brouwer, whether or not unrestricted universal quantification is admissible. Summing this discussion up, and articulating his own view, Carnap writes:

In the foregoing, we have discussed several examples of negative requirements […] by which certain common forms of language—methods of expression and of inference—would be excluded. Our attitude to requirements of this kind is given as a general formulation in the Principle of Tolerance: It is not our business to set up prohibitions, but to arrive at conventions. […] In logic there are no morals. Everyone is at liberty to build up his own logic, i.e., his own form of language, as he wishes.

([12], pp. 51–52. Original emphasis.)

The question that will occupy us here is how we should understand this principle. According to one reading of it, Carnap is willing to countenance many logics as long as they meet certain minimal requirements. For example, these requirements might include: (a) that logics must be expressed with syntactic (as opposed to semantic) rules, or (b) that they must be consistent (or maybe just non-trivial), and so on. On the face of it, this reading is quite plausible. After all, Carnap seems to say as much in his articulation of the principle itself: “[I]f he wishes to discuss [his choice of logic], then he must state his methods clearly, and give syntactical rules instead of philosophical arguments.” ([12], p. 53. My emphasis). In what follows, however, I will argue that this natural reading of the principle is not correct. I will show that he is willing to go much farther than the natural reading would suggest and, in fact, that he wants to throw off all a priori restrictions on logics.

The first clues as to the extent to which Carnap wants his tolerance to be taken are found in the foreword to LSL. There he says:

Up to the present, there has been only a very slight deviation […] from the form of language developed by Russell which has already become classical. […] The fact that no attempts have been made to venture still further from the classical forms is perhaps due to the widely held opinion that any such deviations must be justified—that is, that the new language-form must be proved to be ‘correct’ and to constitute a faithful rendering of ‘the true logic’.

To eliminate this standpoint, together with the pseudo-problems and wearisome controversies which arise as a result of it, is one of the chief tasks of this book. In it, the view will be maintained that we have in every respect complete liberty with regard to the forms of language […].

([12], pp. xiv–xv)

The last sentence is telling: “we have in every respect complete liberty”. We are told quite directly here that there are no restraints on the forms of language that can be considered. One may well worry, however, that forewords can be written in a polemical style, and Carnap may be stating his case less carefully than he might in the main body of the book. However, similar statements can be found in several places: in §16 (“When we here construct our Language I in such a way that it fulfils [sic] certain conditions laid down by Intuitionism, we do not mean thereby to suggest that this is the only possible or justifiable form of language” ([12], pp. 46–47)), in §16a (“The whole thing is only a question of the establishment of a convention whose technical efficiency can be discussed. No fundamental reasons exist why the second or third of these methods should not be used instead of the first in Languages I and II” ([12], p. 49)), and §17 (“Everyone is at liberty to build up his own logic, i.e., his own form of language, as he wishes” ([12], p. 52)) to list a few. The most striking example, however, is once again from the foreword:

For language, in its mathematical form, can be constructed according to any one of the viewpoints represented; so that no question of justification arises at all, but only the question of the syntactical consequences to which one or the other choice leads, including the question of non-contradiction.

([12], p. xv. My emphasis.)

This comment shows just how far Carnap was willing to go—especially in conjunction with his comments in §17: “In many cases, this is brought about by simultaneous investigation (analogous to that of Euclidean and non-Euclidean geometries) of language-forms of different kinds—for instance, a definite language, or indefinite language admitting and one not admitting the Law of Excluded Middle” ([12], p. 51). While other authors at the time were willing to expand classical logic to include formalizations of necessity and possibility, or with many truth values, Carnap even wanted to throw open the gates to logics that were contradictory or did not admit the law of the excluded middle. From the perspective of the early 21st Century, this might not sound so radical, but for 1934, it was very uncommon. Thus, we see that Carnap explicitly rejects placing restrictions on the kinds of inference rules we must accept for a language to count as a logic. However, what about other kinds of restrictions that are often imposed?

Another common thought is that, for a language to be a logic, it must be formal in some important sense.5 Frequently, the final sentence of the principle of tolerance is pointed to in this context: “All that is required of him is that, if he wishes to discuss [his choice of logic], he must state his methods clearly, and give syntactical rules instead of philosophical arguments” ([12], p. 52). Certainly, on the surface this could be read as a requirement of formality—after all, the demand is for ‘syntactical rules’ and not ‘philosophical arguments’. Indeed, in the section on Intuitionism, which immediately precedes the principle of tolerance, Carnap remarks that it is difficult to tell whether or not his Language I accurately captures what Intuitionists want in a logic because their desiderata “are, as a rule, only vaguely formulated” because the Intuitionists “are of the opinion that a calculus is something inessential, a merely supplementary appendix” to their philosophical discussions ([12], p. 46). That is, he seems to be saying that until someone presents a formalized logic, it is hard to tell what exactly their philosophical views amount to. Therefore, there is a sense in which formality is required, as otherwise, others cannot evaluate the language on offer. However, this reading is undermined when we carefully attend to what is actually said in the principle.

First, we note that the demand Carnap makes is only relevant in the case “he wishes to discuss [his choice of logic]”. That is, it is only relevant in cases of collective investigations—no such formality is required in the privacy of one’s mind. Secondly, there is no discussion of what is to count as a syntactical rule. Quite the opposite, we instead find a discussion of whether or not a logic should be presented in words only, symbols only, or in a mix of both symbols and words; true to form, Carnap says that it is context-dependent (though, he does say that, in general, a mix of symbols and words is the clearest in his view ([12], p. 160).6 Therefore, the demand is really for a kind of manual that teaches others how to use the proposed language in question.

Therefore, to return to the extent of the principle, if Carnap is willing to throw out demands for formality, any commitment to a particular set of inference rules, and even an antecedent commitment to consistency, does that mean that all bets are off and that anything goes in logic? The short answer is yes, albeit with very substantial qualifications. Carnap conceives of logics as constructed for some purpose—perhaps one wants to capture classical arithmetic, or maybe relativistic physics, or the grammar of the German language; no matter what the intended phenomena, there must be some reason or other that a language is constructed. And constructed they are, as Carnap thinks that views whereby logic is imposed on us, either by our constitution (as Kant might have said) or by the world (as per Wittgenstein) are simply wrong; his reasons will be made clear in Section 3 below. Since logics are constructed for some purpose, the question becomes: of the logics that have been constructed for this purpose, which should I adopt?

The most obvious answer that one might give is: you should adopt the ‘correct’ logic, where correctness means something like getting things right with respect to the facts about validity. However, this answer is ruled out by Carnap in the early phases of LSL—indeed, he refers to the thought that there is a ‘correct’ logic at all as an “impediment” to progress that has (in the course of LSL) been “overcome” ([12], p. xv). Therefore, if the obvious answer is not available to him, how should Carnap address choosing a logic? The answer comes just a short way into the book. In §16, concerned with Intuitionism, and in §16a, concerned with the identity relation, Carnap addresses how we should adjudicate between rival logics. He says:

Once the fact is realized that all the pros and cons of the Intuitionist discussions are concerned with the forms of a calculus, questions will no longer be put in the form: “What is this or that like?” but instead we shall ask: “How do we wish to arrange this or that in the language to be constructed?” or, from the theoretical standpoint: “What consequences will ensue if we construct a language in this or that way?”

([12], pp. 46–47. Original emphasis.)

It is the comments about the ‘theoretical standpoint’ at the end of the quotation that draws our attention. There, Carnap tells us that we are to be concerned with the consequences of adopting one logic over another—or, at least, the consequences of building our logic one way rather than another. In other words, we must attend to the theoretical virtues that each proposed logic has and weigh our choices accordingly.

Some logics are easier to use than others, some are more expressively powerful, and some are compact, complete, decidable, or consistent; all of these are properties a logic might have that may be desirable for some purposes. The question that presses in on Carnap is how we should weigh up the theoretical virtues a logic has in choosing one to use for some task. Here again, he must say: and there is no one unique way we should do this. That is, we must be tolerant here, too.7 Each person might have their own weightings of these virtues that reflect the different relative importance they assign to each one and thus might make a different choice of logic than another person would, even in the case where they share a purpose. Moreover, we must not suppose that every way of weighting the theoretical virtues a logic might have will produce a uniquely best logic—there might be ties, and this too is a case where we must be tolerant. We cannot insist that our weightings of the theoretical virtues guarantee that there is a unique logic that best instantiates those virtues.

As I read him, we must take Carnap’s somewhat poetic presentation of the principle of tolerance seriously, where he says,

In logic there are no morals. Everyone is at liberty to build up their own logic, i.e., their own language, as he wishes. All that is required of him is that, if he wishes to discuss it, he must state his methods clearly, and give syntactical rules instead of philosophical arguments.

([12], p. 52. Original emphasis.)

I take it that the liberty to build up logics, and even the liberty to evaluate them for suitability, extends as far as possible. No constraints at all can be put on what can be proposed as a logic, and no constraints can be put on how we should evaluate those proposals’ suitability for our purposes. However, there is one brake on this permissiveness which comes when we disagree about how to evaluate logics, or which to pick.

How are we to decide between alternative suggestions of which logic to adopt for some purpose? As above, we ought to weigh the proposals by their theoretical virtues. However, what to do in cases where there is not even agreement on how to weight the virtues? Here, the problem is more thorny. After all, according to my reading of tolerance, Carnap cannot stipulate a ‘correct’ weighting. Instead, we must find some way to come to an agreement about how to choose logics. However, given what has been shown above, we know that this itself will involve stipulating a language—that is, we must construct a language for choosing languages. For if we do not, then we are simply engaged in the “vague [philosophical] preliminaries” to constructing a language from which it will be impossible to tell which language we are choosing ([12], p. 46). Paraphrasing [14], we call such languages ‘selection languages’.

We are finally in a position to sum up the principle of tolerance. There are no a priori restrictions on the construction of logics; the evaluation of a given logic’s suitability for a task is performed by means of a selection language on which there are also no a priori restrictions. At every stage of construction, we are free to decide how we wish to build our logics.

3. Carnap’s Motivations for Pluralism

Thus far, we have explored Carnap’s pluralism by a close examination of his principle of tolerance. The picture that has emerged is of an extremely permissive view. What remains to be discussed is the motivations for this permissive pluralism. That is, if my reading of the principle of tolerance is correct, why would Carnap want to adopt it? In this section, I will argue that the foundation for his permissive philosophy of logic is to be found in the Scientific World-Conception (SWC). In short, I will argue that we must understand the SWC as, in part, a collection of political commitments. Moreover, I will show that Carnap’s logical pluralism is a consequence of the SWC, and so it too is political, at least insofar as the SWC is. The section will conclude with a short discussion of the kind of political engagement the SWC commits one to. In my view, it is not one that is ‘party-political’, but rather political in the sense of committing one to a particular approach to solving collective and social problems.

Central to my understanding of Carnap’s pluralism is the 1929 manifesto of the Vienna Circle: “Wissenschaftliche Weltauffassung: Der Wiener Kreis (The Scientific World-conception: The Vienna Circle)”.8 In it, the authors of the manifesto lay out their metaphilosophical—or, perhaps better, their methodological—commitments, which they call the ‘Scientific World-Conception’. In his study [16], Romizi presents a concise summary of these commitments:

In summary, the SWC is characterized by

1.

The deep appreciation of science and the attribution of a “distinguished” epistemological status to scientific knowledge;

2.

The requirement of conceptual clarity;

3.

The exclusive reliance on empirical evidence and on logically sound arguments as means for acquiring or recognizing genuine knowledge;

4.

Antimetaphysics, as the wish to avoid vague concepts and “uncontrolled” statements. ([16], p. 216)

Romizi goes on to note that these commitments are vague and that they leave the meaning of many of the key terms unspecified. Moreover, this lack of specificity is due to the status of the SWC in the thinking of its authors: it is not a theory that one could establish by argument, but rather “the framework from which one can start to argue” ([16], p. 216). That is, the SWC is an attitude that one could adopt towards philosophical—and logical—investigations. As Carnap puts it, “The scientific world conception is characterized not so much by theses of its own, but rather by its basic attitude, its points of view and direction of research” ([17], pp. 305–306).

It will be helpful to dwell briefly on one particular instance of the vagueness of the characteristics of the SWC. In the third commitment, we are told to rely on “logically sound arguments”. A sound argument is a valid argument with actually true premises. Thus, in order to know that an argument is sound, we must know that it is valid. However, it is not made clear which logic we should use to assess validity. Neither could we have been told which logic to use. For, if we were, it would have to be on the basis of some argument, and any argument must be presented in some logic or other. And, if there were to be a single, universally acceptable logic for assessing the validity of arguments, the argument to the effect that this very same logic is the correct one must be given in it. However, this would, at best, beg the question; at worst, it would be circular. Thus, our assessment of which arguments are sound must be relativized to the logic used to assess their validity. That is, since different logics validate different inferences, we cannot say that an argument is sound simpliciter, but instead can only say that it is sound relative to some logic. Therefore, it would seem that an adherent of the SWC cannot rely on argument to pick a single, uniquely correct logic. Thus, I argue that any adherent of the SWC must be a logical pluralist.9 And finally, insofar as Carnap expresses his own attitude towards philosophical activity in his writing of the SWC, then his logical pluralism will will be consistent with this attitude as well.10

If the SWC is an attitude, and one believes that attitudes are not the sort of thing that one could argue for, then why would anyone adopt this attitude? Some recent literature about the Vienna Circle has attempted to reorient our understanding of their views away from seeing them as a purely theoretical project in academic philosophy, and towards seeing them as engaged in an additional project of active attempts at social reform.11 That is, in addition to the philosophical project, we must see the Circle—in particular, that part of it sometimes called the ‘Left Vienna Circle’, which includes Carnap, Frank, Neurath, and Hahn—as engaged in a political project. In order to see how this bears on our exploration of Carnap’s logical pluralism, we must answer two questions about the SWC: (1) what is the opposing attitude, and (2) in what way the SWC itself is political. We will take them in that order.

In the Circle’s manifesto, Carnap contrasts the SWC with the outlook of their opponents:

The increase in metaphysical and theologizing leanings, which shows itself today in many associations and sects, in books and journals, and in talks and university lectures, seems to be based on the fierce social and economic struggles of the present: one group of combatants, holding fast to traditional social forms, cultivates traditional attitudes of metaphysics and theology […]; while the other group […] faces modern times, rejects these [metaphysical and theologizing] views and takes its stand on the ground of empirical science.

([17], p. 317)

Therefore, the battle lines are drawn between those who adhere to “traditional social forms” and have “metaphysical and theologizing leanings” on the one hand, and those who adopt the SWC on the other. None of this is particularly new—indeed, everyone knows that the Vienna Circle, including Carnap, did not like metaphysics, and it is hardly surprising that they lump theology in with it. What is more important is to understand why they took the attitude they did, which involves answering the second question asked above, namely, in what way is the SWC itself political?

There is very little that is directly political in any of Carnap’s work, if ‘political’ is to be understood as endorsing the view of one political party of an organization; on that same understanding, neither is there anything even in the manifesto that asserts a particular (party) political view.12 George Reisch concludes on this basis that Carnap did not see his philosophical work as political and attempts to show that Carnap is an exemplar of an attitude whereby philosophy is completely separable from politics ([5], pp. 48–50).13 And, at least on the face of it, Reisch is on solid ground. After all, in his Intellectual Autobiography, Carnap says:

All of us in the Circle were strongly interested in social and political progress. Most of us, myself included, were socialists. But we liked to keep our philosophical work separated from our political aims.

([2], pp. 21–22)

However, as I will argue below, this separation needs unpacking, and importantly, the meaning of the word ‘political’, as Carnap uses it here, takes on a different cast when we distinguish different kinds of political aims.

Romizi argues in [16] that, when understood in its proper historical context, the apparently apolitical assertions in the manifesto become, while still not party-political, political nonetheless. That is, what we will not find in Carnap’s work is an exhortation to support the aims of any one particular political party. However, we do find comments like the following from the introduction to the Aufbau:

We feel an inner kinship between the attitude on which our philosophical work is founded and the intellectual attitude which presently manifests itself in entirely different walks of life; we feel this orientation in artistic movements, especially in architecture, and in movements which strive for meaningful forms of personal and collective life, of education, and of external organization in general. […] It is an orientation which acknowledges the bonds that tie men together, but at the same time strives for free development of the individual.

([25], p. xviii)

And, Carnap takes a similar tack in the manifesto, saying:

We witness the spirit of the scientific world-conception penetrating in growing measure the forms of personal and public life, in education, upbringing, architecture, and the shaping of economic and social life according to rational principles.

([17], pp. 317–318)

It is important to notice that all the areas in which the SWC is “penetrating in growing measure”, and with which Carnap’s attitude towards philosophy has “an inner kinship”, are areas outside of academic philosophy and logic. They primarily concern the way people live their lives: education, economics, where they live (architecture), and the way people arrange their society as a whole (public life).14 Therefore, the SWC is an attitude that infuses one’s approach to life in general, and in particular one’s approach to the ways in which people might arrange their collective activities—that is, their political activities. Again, though, I must stress that the SWC does not dictate which specific ways of arranging our lives we must adopt, but rather it shows the way we ought to investigate such questions.

Elsewhere, Reisch argues that all Carnap is committed to in the approach I have described so far is what he calls “Type-1 political engagement”:

We can call this ‘‘Type-1” political engagement: a philosopher chooses an axe to grind with public or social relevance and then brings to bear his or her expertise and research to make a case for one side or the other. Examples include […] Feigl’s writings for The Humanist magazine and Carnap’s signatures in support of disarmament and dialogue between the superpowers (informed as those were, he told Hook, by his contempt for “gross exaggerations” (in Reisch 2005, 282).

([6], p. 195)

However, this undersells the content of the SWC. As I argued above, insofar as one must be a logical pluralist if one adopts the SWC, and insofar as the SWC itself is a political program, then Carnap’s logical pluralism is also consistent with that political program. Moreover, Carnap understood there to be a continuity between his work in logic and the SWC, as he makes clear in the manifesto:

Nevertheless the work of ‘philosophic’ or ‘foundational’ investigations remains important in accord with the scientific world-conception. For the logical clarification of scientific concepts, statements and methods liberates one from inhibiting prejudices.

([17], p. 316)

Therefore, foundational research, for example, into logics, frees us from prejudices. The kinds of prejudices that we are liberated from include metaphysical and theologizing attitudes but are not limited to these. In particular, elsewhere in the manifesto Carnap makes it clear that amongst the most pernicious forms of prejudice that he believes the SWC helps to overcome are those found in language; one of the consequences of adopting the SWC is the search for forms of language that are “freed from the slag of historical languages” ([17], p. 306). This is not just an anodyne application of philosophical expertise to an issue of public concern, because working with the SWC is itself a political tack. It takes certain approaches to problems to be the correct ones and others to not be. Moreover, it takes a stand on what is to count as evidence in favor of, or against, a particular action or set of policies.

We now have the full measure of Carnap’s pluralism. We have seen the extent of the principle of tolerance in Section 2 above. In this section, we added that the principle is consistent with the SWC—an attitude towards both philosophical investigation as well as toward the way we organize life in general. It is, therefore, a political view, as is Carnap’s tolerance. I call this understanding of his view ‘politically engaged logical pluralism’. The question that remains is why this connection is not well known outside the rather narrow confines of Vienna Circle scholarship, and it is to this I now turn.

4. Carnap’s Politically Engaged Logical Pluralism in the American Context

We have seen that, at least in the 1920s and 1930s, Carnap envisioned his work on logic as part of a larger program for societal reform. There are two final issues to address. Firstly, what happened to this program of social reforms? And, secondly, what should we make of Carnap’s claims in the published version of his Intellectual Autobiography to the effect that philosophical work and political work must be kept separate? In this section, I will argue that the answers to these questions are related. I begin with a discussion of the political environment in which Carnap found himself when he arrived in the United States.

Carnap began looking for work in the United States in 1933, after the Nazis seized power in Germany, and eventually managed to make the move in 1936.15 The reasons for his move may be obvious in retrospect; suffice it to say that the Nazi regime was murderously hostile to opposing political ideas and movements. And, the Nazis and their intellectual allies certainly understood those committed to the SWC to be amongst their ideological opponents. For example, as Michael Friedman documents in [9], Heidegger drew a direct connection between the SWC and the forces he understood to be opposed to his views, mentioning Russian communism and the United States in particular.16 On the more public front, the Vienna Circle also sponsored a series of lectures and other forms of public outreach through an organization called the Verein Ernst Mach (“The Ernst Mach Society”) during its final years. This society was perceived by the Austrian government as a left-wing activist organization, so much so that the Dollfuss government attempted to ban the Society.17 The opposition to the Society finally ended when Schlick was murdered on the steps of the University of Vienna, and the official meetings of the Circle and Society ended.18

When Carnap arrived in the United States, he had good reason to hope that the political environment would be more amenable to his ideas. And, for a time, it was. As Reisch documents, many logical empiricists including Carnap found fertile ground for their ideas in the years before the outbreak of the Second World War ([5], pp. 68–69 ff). Logical empiricism was praised in the pages of the Partisan Review and was fashionable amongst a certain set of leftist, and sometimes explicitly communist, intellectuals in and around New York. However, as attitudes towards communism in the United States began to change with the beginnings of the Cold War, so too did attitudes towards the SWC change.

At first, this change might be surprising. For example, in one of the aforementioned Partisan Review articles, “What is Logical Empiricism”, William Gruen is at pains to both distinguish logical empiricism, and the SWC, from Marxist theory and to defend it from Marxist attacks ([27], p. 65). Therefore, one might imagine that as American attitudes towards Marxism soured, the fortunes of a distinct view might not be affected because it was understood to be distinct. Moreover, given the Marxist criticisms of logical empiricism, one might think that the attitude of those Americans who were interested might be one of ‘the enemy of my enemy is my friend’. However, during the 1950s, an active program of anti-communist purges, demands that faculty take loyalty oaths to the United States, and the blacklisting of known communists and communist-sympathizing academics created an environment where espousing any left-wing political agenda at all made academic life dangerous for those, like the adherents of the SWC, who saw their work as bearing directly on political matters.19 Moreover, many academics, Carnap included, were investigated by the FBI.

According to McCumber in [3], there was a dramatic change specifically in American philosophy during this time. In short, McCumber argues that American philosophy, as examined through the lens of the American Philosophical Association, became suddenly quite hostile to reflections on the role of philosophy, science, and philosophy of science in wider social and political life after the mid-1950s. On this basis, McCumber concludes that American philosophy’s self-conception was changing and that it was doing so due to pressures from the concurrent anti-communist crusades.

Carnap had never made a particular secret of his personal political views. As a young man, he wrote polemical pieces for circulation amongst his friends.20 Later, when he joined the Vienna Circle, he and some of the other younger members had active discussions together about political matters. Carnap reports in his Intellectual Autobiography that many of those members, himself included, were socialists at that time ([2], p. 23). And, as I argued in Section 3 above, he saw his philosophical work as continuous with the political project of the SWC. However, there is a distinct change in the years following his emigration to the United States. In short, both Carnap and the other members of the Circle stopped discussing the political aims of their project and certainly did not publish polemical tracts like the manifesto anymore.21 Though he did still participate in some political actions, if these actions were continuous with the content of his philosophical views, Carnap never publicized that fact.22 Therefore, given the change in his work, and his acute awareness of the changes in American philosophy, I think we are warranted in concluding that Carnap did not feel that it was safe to make it plain that his academic work—as opposed to his personal activity—was at all continuous with a political agenda.

However, ref. [4] offers a number of helpful complications to the story. There, Howard notes that there are, in fact, four potential explanations for the very real changes that McCumber noted. (1) It could be as McCumber suggested a response to anti-communist pressure. However, (2) it could also have been due to a more passive “domestication” process whereby the desire to chase money from the National Science Foundation and the Department of Defense necessitated a change in tone, which is a far cry from any active governmental pressure. (3) It could have simply been because, once the former members of the Circle had emigrated to the United States, the political struggles of pre-war Central Europe seemed less pressing than they once had. Finally, (4) perhaps the specific personalities of the Circle emigres that moved to the United States were less interested in the ties between their philosophical work and their personal political beliefs. I think (3) is convincing, but only if we construe the political struggles that the Circle had thought important very narrowly. That is, while it is highly probable that the exact political concerns that the Circle emigres engaged with changed over time, what seems to be the case from Carnap’s activities is that he never lost interest in politics and political action. Thus, I also see reason (4) as not particularly plausible in Carnap’s case. It seems to me that he never lost his commitment to the SWC. Therefore, if my argument in Section 3 above is correct, it means that the link between his personal political actions and his philosophical work remained unchanged. Thus, we are left with the more difficult task of trying to disentangle (1) and (2), a task well beyond what can be done in this paper. However, to leave matters here would be to miss Howard’s larger point, namely that these four potential causes are not exclusive of each other. Most likely, they are all factors that contributed to the (merely) apparent severing of the link between the SWC and the political ambitions of its adherents, including Carnap.

There is one last complication to my argument that must be addressed before concluding, namely Carnap’s explicit denial of there being any political content to the philosophical views of the Vienna Circle. Therefore, while he freely expresses his personal political views (e.g., at [2], pp. 82–83), he makes sure to note that the Circle did not discuss political matters in its meetings. Putting things directly in his Intellectual Autobiography, he says:

But we liked to keep our philosophical work separated from our political aims. In our view, logic, including applied logic, and the theory of knowledge, the analysis of language, and the methodology of science, are, like science itself, neutral with respect to practical aims, whether they are moral aims for the individual, or political aims for a society.

([2], p. 23. My emphasis.)

Given what I have argued above, namely that the Circle emigres, including Carnap, intentionally tried to distance themselves from their earlier views in order to avoid governmental scrutiny, what is to be made of the stance he adopts here? Since his work at this time was still committed to the SWC, it seems to me at least possible that it was advantageous for Carnap to say that his work was politically neutral. That is, since he had already had to flee one country and been investigated by the government of his adopted new one in the form of the FBI, he would have been acutely aware of the danger at that time of saying that his academic work was in any way political.

5. Conclusions

This paper began with a question: to what extent, if at all, did the content of the philosophical positions of members of the Vienna Circle reflect their social and political views? In order to make the question more manageable, I restricted my attention to only looking at the views of Rudolf Carnap, and further, to looking at his philosophy of logic. To begin, I had to establish what Carnap’s philosophy of logic was. I argued that he is best understood as a logical pluralist of a radically open kind. His pluralism is one in which there cannot be any a priori restrictions of what is to count as a logic, or on which logics can be proposed for use. At the end of that section, I argued that my interpretation of Carnap does not suffer from a regress problem, and it is possible to choose a logic in a non-arbitrary and non-circular fashion.

Equipped with this understanding of Carnap’s philosophy of logic, I turned my attention to why he might have wanted to adopt such a permissive view. There, I dug into the philosophical program of the Vienna Circle, the scientific world-conception. I argued that the SWC was inherently political, and not just in motivation, but in content—not party-political, but nonetheless concerned directly with making use of philosophical tools to bring about social change. Further, I argued that adopting the SWC commits one to adopting a Carnapian logical pluralism. Thus, insofar as one is committed to the SWC, and insofar as its content is political, then so too is Carnap’s logical pluralism.

Finally, I asked why the connection between the content of Carnap’s philosophical views about logic and his political views is not better known outside the community of scholars working on the Vienna Circle. The answer I gave involved an examination of Carnap’s move to the United States and the political environment at the time. Though matters are complicated by historical events rarely having a single definable cause, I argued that the Circle emigres intentionally distanced themselves from their earlier work, which made the political content of their view obvious. Moreover, they simply stopped discussing the political part of the view. Thus, though Carnap had many students, and his work was widely read, philosophers did not appreciate the extent to which politics plays a role in the philosophical positions he took. Thus, the kind of philosophy that emerged from those philosophers who engaged with Carnap’s work was focused solely on the apparently non-political portions of it. And so the apolitical image of analytic philosophy emerges from the defanged presentation that these other philosophers engaged with.