Despite the refinements that have been made to the basic tenets of the early Vienna Circle, logical positivism remains identified with physicalism, the unity of science, a rejection of metaphysics, and non-cognitivism; an overall outlook, at least in its implicit moderate form, that has become dominant among most practicing (natural) scientists.

As a general rule, the more obscurantist and multi-interpretable a philosopher, the higher the probability (s)he will be admitted to the ranks of “important thinkers.” Therefore, as one browses the philosophy section in a book store one should expect to find numerous books on Martin Heidegger and Theodor Adorno, and little, or nothing, on systematic and disciplined writers like Rudolf Carnap or Hans Reichenbach.

In the case of Carnap this situation is changing. For a long while, Carnap was being perceived as an outdated thinker whose contributions had been “refuted” by Karl Popper and other critics of logical positivism.  In the case of Karl Popper this opinion has been further reinforced by Popper the person, reflecting his desire to establish himself as an important philosopher by distancing himself from the philosophers of the Vienna Circle.  In his essay on Popper, Martin Gardner writes that  “it seems that every time Carnap expressed an opinion, Popper felt compelled to come forth with an opposing view, although it usually turned out to be the same as Carnap’s but in different language.”

In hindsight, Popper’s vanity has been unfortunate because both philosophers would most likely have been appalled with the state of contemporary philosophy. The differences between Popper and Carnap  are a lot smaller than the differences between them and what constitutes “critical thinking” today. What could have been a potential refinement of logical positivism became “critical rationalism.”

Since Rudolf Carnap has the reputation of being a bone dry and technical philosopher who did not allow hyperbole, moralism, and politics in his published philosophical writings (presumably because he recognized the challenge, if not  impossibility, of linking his technical writings and political views in a logical manner), one would think it would be impossible to use Carnap’s technical writings as a starting point for social philosophy. Enter A. W. Carus’s Carnap and Twentieth-Century Thought: Explication as Enlightenment, who takes on this task.

The author of this book must have realized himself that  his proposal has a strong subjective component, as evidenced by the following self-conscious passages from the Preface and Introduction:

“The purpose of this book is to describe that proposal , to make it more explicit than Carnap did…”

“In the particular case of the Vienna Circle, certain assumptions about the broader cultural and ethical context of their philosophical project were so obvious to them they were never made explicit in their writings.”

“But although he remained politically aware during his American years, and involved in radical politics, he made no effort whatever to connect these activities with the philosophical work he was publishing.”

Towards the end of the introduction, Carus informs us that he will not engage with  most of Carnap’s specific technical writings but proposes to work out a “general programme of explication”, “something toward which Carnap approached, in his later years, but which never quite crystallized, probably not even in his own mind.”

It cannot be denied that Carnap had political interests that preceded or continued during his academic work. As a number of quotations from Carnap’s autobiography make clear, Carnap certainly had an interest in political matters and was even engaged in political organization throughout his life (for example, Carus mentions Carnap’s apparent sympathy for the socialist anarchism of Gustav Landauer). But some writers cannot resist to treat these personal political and cultural ambitions as necessary linked to (or a prerequisite for) their technical work, an exercise that seems to me just as futile as envisioning the idea of a “socialist chemistry” or a “feminist physics.”

Moreover, to the extent that there are indications of ideological bias in someone’s scientific work (Otto Neurath’s writings may be a good example) the proper approach is to highlight those and separate them from the meaningful (sic) work. Carus’s approach, on the other hand, seems to embrace such tendencies and further amplifies them, an attitude that seems to be highly at odds with the logical positivist tradition and presents a formidable obstacle to clear and disciplined thinking.

The result is a book that cannot seem to decide what it wants to be (see Alan Richardson’s review on this point).  The introduction and the final chapter of the book attempt to link Carnap to a specific cultural, if not political, philosophy and produces a rather artificial and arbitrary brew as a result. The remaining bulk of the text is a well researched and interesting review of the evolution of Carnap’s (early) thinking. No doubt the author could claim that these two elements are not mutually exclusive, perhaps even complementary to each other, but the parts in which the author allows more space for Carnap’s broader ambitions convey as much information about the author as about Carnap.

Even if an attempt along the lines of this book is made it does not strike me as obvious to place the relevance of Carnap’s thought in debates such as those between John Rawls and Jürgen Habermas.  The tradition of logical positivism, and its associated meta-ethical theory of non-cognitivism, seems to be more compatible  with an outlook that is influenced by evolutionary or game-theoretical approaches to social phenomena.

Although Carnap has admitted in his autobiographical writings to have remained sympathetic to a planned economy and world government, the general worldview that was implicit in the logical-empiricist movement permits secular views ranging from analytical marxism to “right wing” counter-modernism. This tolerance to various interpretations of the Enlightenment is very clear in its 1929 “manifesto” “The Scientific Conception of the World: The Vienna Circle”, which mentions Adam Smith as well as Karl Marx as predecessors of a scientific and anti-metaphysical attitude.

In my opinion, if there is an urgent matter in which the perspective of logical positivism can be of important value it is the explicit  post-war taboo on the use of evolutionary biology in the shaping and evaluation of public policy. Although a logical-empiricist approach may not be be able to shed light on the formation and persistence of this taboo (although public choice might), it can critically analyze the arguments that have been offered to justify the “modern denial of human nature.” I do not think that it would be proper to offer this proposal in a book about Carnap though. And this brings us back to the topic at hand. The renewed interest in Carnap is wonderful and deserved, but I’d rather see works on Carnap that are more modest and which do not propose “a framework of discourse in which a utopian partnership for reason and Enlightenment can co-exist with a pluralism more radical and fundamental than that envisaged by liberal political philosophers such as Rawls.”

One of the real strengths of the logical positivists was how their views were shaped by modern developments in the physical sciences and mathematics. Carnap’s work can benefit from placing it in a broader perspective but I think that it will be more  illuminating to review his relevance in light of recent developments in science instead of contrasting his thinking with other (political) philosophers. There is a lot of contemporary work in science that is close to the spirit of Carnap’s thinking, and logical empiricism in general, but it is rarely identified as such because many of these scientists (physicists, biologists, neuroscientists, etc.) are not aware of the empiricist and anti-metaphysical premises in their work.