The Day Thread of Rudolf Carnap

Do you have a favorite philosopher? I do! Rudolf Carnap was one of the founders and leading exponents of Logical Positivism, and I think it’s a shame that most people don’t know his name.

Born in 1891, Carnap studied physics at the University of Jena in Germany. While there, he also studied Kant’s Critique of Pure Reason and attended classes on mathematical logic taught by Gottlob Frege (who had made what I’d consider the greatest advance in the field of pure logic since Aristotle). Carnap wrote a thesis that the physics department rejected for being too philosophical and the philosophy department rejected for being too scientific. He eventually had to write a new thesis that better toed the Kantian line before receiving a degree in philosophy.

Despite the influence of Kantian thought, Carnap was stimulated by Frege, as well as by his correspondence with Bertrand Russell and a series of seminars by Edmund Husserl, to move toward a more analytical and phenomenological approach to philosophy. He accepted a position at the University of Vienna, where he met a group of like-minded intellectuals, and, largely at Carnap’s instigation, they organized a formal philosophy club called the Vienna Circle, aimed at exploring and promoting what they saw as a new approach to philosophy.

For all the nuance and jargon attached to this philosophical tradition, the basic ideas that motivated them are not hard to understand. The core of it was this: Because all we know about the world is what our senses tell us, the only things we can meaningfully talk about are the things that we can empirically observe. That’s a pretty simple idea, isn’t it? And yet it was a radical one; for millennia, philosophers (for the most part) saw nothing even potentially problematic in talking about things that could not be observed at all, and arguing over statements that were completely unverifiable and unfalsifiable – from Plato’s “essences” to Kant’s “things-in-themselves” and beyond. The Vienna Circle’s goal was to rid philosophy of all this meaningless metaphysical baggage, as they saw it, and apply a stricter, more scientific, standard of logical analysis to philosophical questions.

But wait, you may say, don’t we talk about things that are not empirically observable all the time, even in science? Do you, Aiwendil (I can hear you asking), not study neutrinos – particles that can’t be seen or felt or heard? Well, yes, that’s true, but the key is that they can be detected. They can produce signals in our instruments, which in turn produce numbers and images on their displays, which I can see. Carnap’s idea was that every valid scientific statement ought to be translateable into statements that were purely about immediate sensory experiences – images, sounds, and the like. In his most famous work, The Logical Structure of the World, he attempted to actually develop a translation scheme that could take any scientific statement and turn it into a set of statements purely about the human senses.

That attempt failed, for reasons both technical and conceptual, and before long pointed critiques of the Logical Positivist enterprise began to appear, and its brief hegemony over philosophical thought (at least in the English-speaking world) began to wane. Its death knell may perhaps be identified as W.V.O. Quine’s extremely influential paper, “Two Dogmas of Empiricism”, a very astute critique of some of the ideas at the heart of the Positivist undertaking. But for my money (and this is an opinion that would get me laughed out of most philosophy departments) Carnap was essentially on the right track, and in my more fantastical moments, I sometimes try to continue to work out his ideas.

The Vienna Circle itself, alas, met its demise from something far less gentle than Quine’s pen. Its members were mostly socialists, pacifists, and atheists, and by the mid-1930s, those were not safe things to be in Vienna. One of the leading members of the circle, Moritz Schlick, was murdered in 1936 by a Nazi-sympathizing student. Carnap had fled to the U.S. the previous year, and continued to write until his death in 1970. But he expressed frustration that he was never again able to find a group of peers devoted to the primacy of science and logic in philosophy.